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Farm Engines and How to Run Them: The Young Engineer's Guide

by James H. Stephenson · English · Gutenberg #43867 · 372,645 chars · public domain (US)

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Title: Farm Engines and How to Run Them: The Young Engineer's Guide

Author: James H. Stephenson


        
Release date: October 2, 2013 [eBook #43867]
                Most recently updated: October 23, 2024

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK FARM ENGINES AND HOW TO RUN THEM: THE YOUNG ENGINEER'S GUIDE ***

[Illustration: TRACTION ENGINE.]




  FARM ENGINES AND HOW TO RUN THEM

  _THE YOUNG ENGINEER’S GUIDE_

  A SIMPLE, PRACTICAL HAND BOOK, FOR EXPERTS AS WELL AS
  FOR AMATEURS, FULLY DESCRIBING EVERY PART OF AN ENGINE
  AND BOILER, GIVING FULL DIRECTIONS FOR THE SAFE AND
  ECONOMICAL MANAGEMENT OF BOTH; ALSO SEVERAL
  HUNDRED QUESTIONS AND ANSWERS OFTEN GIVEN IN
  EXAMINATIONS FOR AN ENGINEER’S LICENSE, AND
  CHAPTERS ON FARM ENGINE ECONOMY, WITH
  SPECIAL ATTENTION TO TRACTION AND GASOLINE
  FARM ENGINES, AND A CHAPTER ON

  _The Science of Successful Threshing_

  BY
  JAMES H. STEPHENSON
  _And Other Expert Engineers_

  WITH NUMEROUS ILLUSTRATIONS SHOWING THE DIFFERENT
  PARTS OF A BOILER AND ENGINE, AND NEARLY EVERY MAKE OF
  TRACTION ENGINE, WITH A BRIEF DESCRIPTION OF THE DISTINCTIVE
  POINTS IN EACH MAKE.

  [Illustration]

  CHICAGO
  FREDERICK J. DRAKE & CO.
  PUBLISHERS

  COPYRIGHT, 1903
  BY FREDERICK J. DRAKE & CO.
  CHICAGO, ILL., U.S.A.




PREFACE


This book makes no pretensions to originality. It has taken the best
from every source. The author believes the matter has been arranged in
a more simple and effective manner, and that more information has been
crowded into these pages than will be found within the pages of any
similar book.

The professional engineer, in writing a book for young engineers, is
likely to forget that the novice is unfamiliar with many terms which
are like daily bread to him. The present writers have tried to avoid
that pitfall, and to define each term as it naturally needs definition.
Moreover, the description of parts and the definitions of terms have
preceded any suggestions on operation, the authors believing that the
young engineer should become thoroughly familiar with his engine and
its manner of working, before he is told what is best to do and not
to do. If he is forced on too fast he is likely to get mixed. The
test questions at the end of Chapter III. will show how perfectly the
preceding pages have been mastered, and the student is not ready to go
on till he can answer all these questions readily.

The system of questions and answers has its uses and its limitations.
The authors have tried to use that system where it would do most good,
and employ the straight narrative discussion method where questions
could not help and would only interrupt the progress of thought. Little
technical matter has been introduced, and that only for practical
purposes. The authors have had traction engines in mind for the most
part, but the directions will apply equally well to any kind of steam
engine.

The thanks of the publishers are due to the various traction engine
and threshing machine manufacturers for cuts and information, and
especially to the _Threshermen’s Review_ for ideas contained in its
“Farm Engine Economy,” to the J. I. Case Threshing Machine Co. for
the use of copyrighted matter in their “The Science of Successful
Threshing,” and to the manager of the Columbus Machine Co. for valuable
personal information furnished the authors on gasoline engines and how
to run them. The proof has been read and corrected by Mr. T. R. Butman,
known in Chicago for 25 years as one of the leading experts on engines
and boilers, especially boilers.




THE

YOUNG ENGINEERS’ GUIDE




CHAPTER I.

BUYING AN ENGINE.


There are a great many makes of good engines on the market to-day, and
the competition is so keen that no engine maker can afford to turn out
a very poor engine. This is especially true of traction engines. The
different styles and types all have their advantages, and are good in
their way. For all that, one good engine may be valueless for you, and
there are many ways in which you may make a great mistake in purchasing
an engine. The following points will help you to choose wisely:

1. Consider what you want an engine for. If it is a stationary engine,
consider the work to be done, the space it is to occupy, and what
conveniences will save your time. Remember, TIME IS MONEY, and that
means that SPACE IS ALSO MONEY. Choose the kind of engine that will be
most convenient for the position in which you wish to place it and the
purpose or purposes for which you wish to use it. If buying a traction
engine, consider also the roads and an engine’s pulling qualities.

2. If you are buying a traction engine for threshing, the first thing
to consider is FUEL. Which will be cheapest for you, wood, coal or
straw? Is economy of fuel much of an object with you--one that will
justify you in greater care and more scientific study of your engine?
Other things being equal, the direct flue, firebox, locomotive boiler
and simple engine will be the best, since they are the easiest to
operate. They are not the most economical under favorable conditions,
but a return flue boiler and a compound engine will cost you far more
than the possible saving of fuel unless you manage them in a scientific
way. Indeed, if not rightly managed they will waste more fuel than the
direct flue locomotive boiler and the simple engine.

3. Do not try to economize on the size of your boiler, and at the same
time never get too large an engine. If a 6-horse power boiler will just
do your work, an 8-horse power will do it better and more economically,
because you won’t be overworking it all the time. Engines should seldom
be crowded. At the same time you never know when you may want a higher
capacity than you have, or how much you may lose by not having it. Of
course you don’t want an engine and boiler that are too big, but you
should always allow a fair margin above your anticipated requirements.

4. Do not try to economize on appliances. You should have a good pump,
a good injector, a good heater, an extra steam gauge, an extra fusible
plug ready to put in, a flue expander and a beader. You should also
certainly have a good force pump and hose to clean the boiler, and the
best oil and grease you can get. Never believe the man who tells you
that something not quite the best is just as good. You will find it the
most expensive thing you ever tried--if you have wit enough to find out
how expensive it is.

5. If you want my personal advice on the proper engine to select for
various purposes, I should say by all means get a gasoline engine for
small powers about the farm, such as pumping, etc. It is the quickest
to start, by far the most economical to operate, and the simplest
to manage. The day of the small steam engine is past and will never
return, and ten gasoline engines of this kind are sold for every steam
engine put out. If you want a traction engine for threshing, etc.,
stick to steam. Gasoline engines are not very good hill climbers
because the application of power is not steady enough; they are not
very good to get out of mud holes with for the same reason, and as yet
they are not perfected for such purposes. You might use a portable
gasoline engine, however, though the application of power is not
as steady as with steam and the flywheels are heavy. In choosing a
traction steam engine, the direct flue locomotive boiler and simple
engine, though theoretically not so economical as the return flue
boiler and compound engine, will in many cases prove so practically
because they are so much simpler and there is not the chance to go
wrong with them that there is with the others. If for any reason you
want a very quick steamer, buy an upright. If economy of fuel is very
important and you are prepared to make the necessary effort to secure
it, a return flue boiler will be a good investment, and a really good
compound engine may be. Where a large plant is to be operated and a
high power constant and steady energy is demanded, stick to steam,
since the gasoline engines of the larger size have not proved so
successful, and are certainly by no means so steady; and in such a
case the exhaust steam can be used for heating and for various other
purposes that will work the greatest economy. For such a plant choose a
horizontal tubular boiler, set in masonry, and a compound engine (the
latter if you have a scientific engineer).

In general, in the traction engine, look to the convenience of
arrangement of the throttle, reverse lever, steering wheel, friction
clutch, independent pump and injector, all of which should be within
easy reach of the footboard, as such an arrangement will save annoyance
and often damage when quick action is required.

The boiler should be well set; the firebox large, with large grate
surface if a locomotive type of boiler is used, and the number of flues
should be sufficient to allow good combustion without forced draft.
A return flue boiler should have a large main flue, material of the
required 5-16-inch thickness, a mud drum, and four to six hand-holes
suitably situated for cleaning the boiler. There should be a rather
high average boiler pressure, as high pressure is more economical than
low. For a simple engine, 80 pounds and for a compound 125 pounds
should be minimum.

A stationary engine should have a solid foundation built by a mason who
understands the business, and should be in a light, dry room--never in
a dark cellar or a damp place.

Every farm traction engine should have a friction clutch.




CHAPTER II.

BOILERS.


The first boilers were made as a single cylinder of wrought iron set in
brick work, with provision for a fire under one end. This was used for
many years, but it produced steam very slowly and with great waste of
fuel.

The first improvement to be made in this was a fire flue running the
whole length of the interior of the boiler, with the fire in one end of
the flue. This fire flue was entirely surrounded by water.

Then a boiler was made with two flues that came together at the
smoke-box end. First one flue was fired and then the other,
alternately, the clear heat of one burning the smoke of the other when
it came into the common passage.

The next step was to introduce conical tubes by which the water could
circulate through the main fire flue (Galloway boiler).

[Illustration: FIG. 1. ORR & SEMBOWER’S STANDARD HORIZONTAL BOILER,
WITH FULL-ARCH FRONT SETTING.]

The object of all these improvements was to get larger heating surface.
To make steam rapidly and economically, the heating surface must be as
large as possible.

[Illustration: FIG. 2. GAAR, SCOTT & CO.’S LOCOMOTIVE BOILER.]

But there is a limit in that the boiler must not be cumbersome, it must
carry enough water, and have sufficient space for steam.

The stationary boiler now most commonly used is cylindrical, the fire
is built in a brick furnace under the sheet and returns through fire
tubes running the length of the boiler. (Fig. 1.)


LOCOMOTIVE FIRE TUBE TYPE OF BOILER.

The earliest of the modern steam boilers to come into use was the
locomotive fire tube type, with a special firebox. By reference to
the illustration (Fig. 2) you will see that the boiler cylinder is
perforated with a number of tubes from 2 to 4 inches in diameter
running from the large firebox on the left, through the boiler cylinder
filled with water, to the smoke-box on the right, above which the
smokestack rises.

[Illustration: FIG. 3. THE HUBER FIRE BOX.]

It will be noticed that the walls of the firebox are double, and that
the water circulates freely all about the firebox as well as all about
the fire tubes. The inner walls of the firebox are held firmly in
position by stay bolts, as will be seen in Fig. 3, which also shows the
position of the grate.

[Illustration: FIG. 4. HUBER RETURN FLUE BOILER.]


RETURN FLUE TYPE OF BOILER.

The return flue type of boiler consists of a large central fire flue
running through the boiler cylinder to the smoke box at the front end,
which is entirely closed. The smoke passes back through a number of
small tubes, and the smokestack is directly over the fire at the rear
of the boiler, though there is no communication between the fire at the
rear of the boiler and it except through the main flue to the front and
back through the small return flues. Fig. 4 illustrates this type of
boiler, though it shows but one return flue. The actual number may be
seen by the sectional view in Fig. 5.

[Illustration: FIG. 5. SECTION VIEW OF HUBER RETURN FLUE BOILER.]

The fire is built in one end of the main flue, and is entirely
surrounded by water, as will be seen in the illustration. The long
passage for the flame and heated gases enables the water to absorb a
maximum amount of the heat of combustion. There is also an element of
safety in this boiler in that the small flues will be exposed first
should the water become low, and less damage will be done than if the
large crown sheet of the firebox boiler is exposed, and this large
crown sheet is the first thing to be exposed in that type of boiler.


WATER TUBE TYPE OF BOILER.

The special difference between the fire tube boiler and the water tube
boiler is that in the former the fire passes through the tubes, while
in the latter the water is in the tubes and the fire passes around them.

[Illustration: FIG. 6. FREEMAN VERTICAL BOILER.]

In this type of boiler there is an upper cylinder (or more than one)
filled with water; a series of small tubes running at an angle from the
front or fire door end of the upper cylinder to a point below and back
of the grates, where they meet in another cylinder or pipe, which is
connected with the other end of the upper cylinder. The portions of the
tubes directly over the fire will be hottest, and the water here will
become heated and rise to the front end of the upper cylinder, while to
fill the space left, colder water is drawn in from the back pipe, from
the rear end of the upper cylinder, down to the lower ends of the water
tubes, to pass along up through them to the front end again.

This type of boiler gives great heating surface, and since the tubes
are small they will have ample strength with much thinner walls. Great
freedom of circulation is important in this type of boiler, there being
no contracted cells in the passage. This is not adapted for a portable
engine.


UPRIGHT OR VERTICAL TYPE OF BOILER.

In the upright type of boiler the boiler cylinder is placed on end,
the fire is built at the lower end, which is a firebox surrounded by a
water jacket, and the smoke and gases of combustion rise straight up
through vertical fire flues. The amount of water carried is relatively
small, and the steam space is also small, while the heating surface is
relatively large if the boiler is sufficiently tall. You can get up
steam in this type of boiler quicker than in any other, and in case of
the stationary engine, the space occupied is a minimum. The majority
of small stationary engines have this type of boiler, and there is a
traction engine with upright boiler which has been widely used, but
it is open to the objection that the upper or steam ends of the tubes
easily get overheated and so become leaky. There is also often trouble
from mud and scale deposits in the water leg, the bottom area of which
is very small.


DEFINITION OF TERMS USED IN CONNECTION WITH BOILERS.

_Shell_--The main cylindrical steel sheets which form the principal
part of the boiler.

_Boiler-heads_--The ends of the boiler cylinder.

_Tube Sheets_--The sheets in which the fire tubes are inserted at each
end of the boiler.

_Fire-box_--A nearly square space at one end of a boiler, in which the
fire is placed. Properly it is surrounded on all sides by a double
wall, the space between the two shells of these walls being filled with
water. All flat surfaces are securely fastened by stay bolts and crown
bars, but cylindrical surfaces are self-bracing.

_Water-leg_--The space at sides of fire-box and below it in which water
passes.

_Crown-sheet_--The sheet of steel at the top of the firebox, just under
the water in the boiler. This crown sheet is exposed to severe heat,
but so long as it is covered with water, the water will conduct the
heat away, and the metal can never become any hotter than the water
in the boiler. If, however, it is not covered with water, but only by
steam, it quickly becomes overheated, since the steam does not conduct
the heat away as the water does. It may become so hot it will soften
and sag, but the great danger is that the thin layer of water near this
overheated crown sheet will be suddenly turned into a great volume
of steam and cause an explosion. If some of the pressure is taken
off, this overheated water may suddenly burst into steam and cause an
explosion, as the safety valve blows off, for example (since the safety
valve relieves some of the pressure).

_Smoke-box_--The space at the end of the boiler opposite to that of the
fire, in which the smoke may accumulate before passing up the stack in
the locomotive type, or through the small flues in the return type of
boiler.

_Steam-dome_--A drum or projection at the top of the boiler cylinder,
forming the highest point which the steam can reach. The steam is taken
from the boiler through piping leading from the top of this dome, since
at this point it is least likely to be mixed with water, either through
foaming or shaking up of the boiler. Even under normal conditions the
steam at the top of the dome is drier than anywhere else.

_Mud-drum_--A cylindrical-shaped receptacle at the bottom of the boiler
similar to the steam-dome at the top, but not so deep. Impurities in
the water accumulate here, and it is of great value on a return flue
boiler. In a locomotive boiler the mud accumulates in the water leg,
below the firebox.

_Man-holes_--Are large openings into the interior of a boiler, through
which a man may pass to clean out the inside.

_Hand-holes_--Are smaller holes at various points in the boiler into
which the nozzle of a hose may be introduced for cleaning out the
interior. All these openings must be securely covered with steam-tight
plates, called man-hole and hand-hole plates.

_A boiler jacket_--A non-conducting covering of wood, plaster, hair,
rags, felt, paper, asbestos or the like, which prevents the boiler
shell from cooling too rapidly through radiation of heat from the
steel. These materials are usually held in place against the boiler by
sheet iron. An intervening air-space between the jacket and the boiler
shell will add to the efficiency of the jacket.

_A steam-jacket_--A space around an engine cylinder or the like which
may be filled with live steam so as to keep the interior from cooling
rapidly.

_Ash-pit_--The space directly under the grates, where the ashes
accumulate.

_Dead-plates_--Solid sheets of steel on which the fire lies the same as
on the grates, but with no openings through to the ash-pit. Dead-plates
are sometimes used to prevent cold air passing through the fire into
the flues, and are common on straw-burning boilers. They should seldom
if ever be used on coal or wood firing boilers.

_Grate Surface_--The whole space occupied by the grate-bars, usually
measured in square feet.

_Forced Draft_--A draft produced by any means other than the natural
tendency of the heated gases of combustion to rise. For example, a
draft caused by letting steam escape into the stack.

_Heating Surface_--The entire surface of the boiler exposed to the heat
of the fire, or the area of steel or iron sheeting or tubing, on one
side of which is water and on the other heated air or gases.

_Steam-space_--The cubical contents of the space which may be occupied
by steam above the water.

_Water-space_--The cubical contents of the space occupied by water
below the steam.

_Diaphragm-plate_--A perforated plate used in the domes of locomotive
boilers to prevent water dashing into the steam supply pipe. A dry-pipe
is a pipe with small perforations, used for taking steam from the
steam-space, instead of from a dome with diaphragm-plate.


THE ATTACHMENTS OF A BOILER.[1]

Before proceeding to a consideration of the care and management of
a boiler, let us briefly indicate the chief working attachments of
a boiler. Unless the nature and uses of these attachments are fully
understood, it will be impossible to handle the boiler in a thoroughly
safe and scientific fashion, though some engineers do handle boilers
without knowing all about these attachments. Their ignorance in many
cases costs them their lives and the lives of others.

  Footnote 1: Unless otherwise indicated, cuts of fittings show those
    manufactured by the Lunkenheimer Co., Cincinnati, Ohio.

The first duty of the engineer is to see that the boiler is filled with
water. This he usually does by looking at the glass water-gauge.


THE WATER GAUGE AND COCKS.

[Illustration: TWO-ROD WATER GAUGE.]

There is a cock at each end of the glass tube. When these cocks are
open the water will pass through the lower into the glass tube, while
steam comes through the other. The level of the water in the gauge will
then be the same as the level of the water in the boiler, and the water
should never fall out of sight below the lower end of the glass, nor
rise above the upper end.

Below the lower gauge cock there is another cock used for draining
the gauge and blowing it off when there is a pressure of steam on. By
occasionally opening this cock, allowing the heated water or steam to
blow through it, the engineer may always be sure that the passages
into the water gauge are not stopped up by any means. By closing the
upper cock and opening the lower, the passage into the lower may be
cleared by blowing off the drain cock; by closing the lower gauge cock
and opening the upper the passage from the steam space may be cleared
and tested in the same way when the drain cock is opened. If the glass
breaks, both upper and lower gauge cocks should be closed instantly.

[Illustration: GAUGE OR TRY COCK.]

In addition to the glass water gauge, there are the try-cocks for
ascertaining the level of the water in the boiler. There should be two
to four of these. They open directly out of the boiler sheet, and by
opening them in turn it is possible to tell approximately where the
water stands. There should be one cock near the level of the crown
sheet, or slightly above it, another about the level of the lower gauge
cock, another about the middle of the gauge, another about the level of
the upper gauge, and still another, perhaps, a little higher. But one
above and one below the water line will be sufficient. If water stands
above the level of the cock, it will blow off white mist when opened;
if the cock opens from steam-space, it will blow off blue steam when
opened.

The try-cocks should be opened from time to time in order to be sure
the water stands at the proper level in the boiler, for various things
may interfere with the working of the glass gauge. Try-cocks are often
called gauge cocks.

[Illustration: TRY COCK.]


THE STEAM GAUGE.

The steam gauge is a delicate instrument arranged so as to indicate by
a pointer the pounds of pressure which the steam is exerting within the
boiler. It is extremely important, and a defect in it may cause much
damage.

[Illustration: PRESSURE GAUGE.]

The steam gauge was invented in 1849 by Eugene Bourdon, of France.
He discovered that a flat tube bent in a simple curve, held fast at
one end, would expand and contract if made of proper spring material,
through the pressure of the water within the tube. The free end
operates a clock-work that moves the pointer.

It is important that the steam gauge be attached to the boiler by a
siphon, or with a knot in the tube, so that the steam may operate on
water contained in the tube, and the water cannot become displaced by
steam, since steam might interfere with the correct working of the
gauge by expanding the gauge tube through its excessive heat.

Steam gauges frequently get out of order, and should be tested
occasionally. This may conveniently be done by attaching them to a
boiler which has a correct gauge already on it. If both register alike,
it is probable that both are accurate.

[Illustration: STEAM GAUGE SIPHON.]

[Illustration: FRONT CYLINDER COCK.]

There are also self-testing steam gauges. With all pressure off,
the pointer will return to 0. Then a series of weights are arranged
which may be hung on the gauge and cause the pointer to indicate
corresponding numbers. The chief source of variation is in the
loosening of the indicator needle. This shows itself usually when the
pressure is off and the pointer does not return exactly to zero.


SAFETY VALVE.

The safety valve is a valve held in place by a weighted lever[2] or
by a spiral spring (on traction engines) or some similar device, and
is adjustable by a screw or the like so that it can be set to blow
off at a given pressure of steam, usually the rated pressure of the
boiler, which on traction engines is from 110 to 130 pounds. The valve
is supplied with a handle by which it can be opened, and it should
be opened occasionally to make sure it is working all right. When it
blows off the steam gauge should be noted to see that it agrees with
the pressure for which the safety valve was set. If they do not agree,
something is wrong; either the safety valve does not work freely, or
the steam gauge does not register accurately.

  Footnote 2: This kind of safety valve is now being entirely discarded
    as much more dangerous than the spring or pop valve.

[Illustration: SECTIONAL VIEW OF KUNKLE POP VALVE.]

[Illustration: SAFETY VALVE.]

The cut shows the Kunkle safety valve. To set it, unscrew the jam nut
and apply the key to the pressure screw. For more pressure, screw
down; for less, unscrew. After having the desired pressure, screw the
jam nut down tight on the pressure screw. To regulate the opening
and closing of the valve, take the pointed end of a file and apply it
to the teeth of the regulator. If valve closes with too much boiler
pressure, move the regulator to the left. If with too little, move the
regulator to the right.

This can be done when the valve is at the point of blowing off.

[Illustration: PHANTOM VIEW OF MARSH INDEPENDENT STEAM PUMP.]

Other types of valves are managed in a similar way, and exact
directions will always be furnished by the manufacturers.


FILLING THE BOILER WITH WATER.

There are three ways in which a boiler is commonly filled with water.

First, before starting a boiler it must be filled with water by hand,
or with a hand force-pump. There is usually a filler plug, which must
be taken out, and a funnel can be attached in its place. Open one of
the gauge cocks to let out the air as the water goes in.

When the boiler has a sufficient amount of water, as may be seen by
the glass water gauge, replace the filler plug. After steam is up the
boiler should be supplied with water by a pump or injector.


THE BOILER PUMP.

There are two kinds of pumps commonly used on traction engines, the
Independent pump, and the Cross-head pump.

The Independent pump is virtually an independent engine with pump
attached. There are two cylinders, one receiving steam and conveying
force to the piston; the other a water cylinder, in which a plunger
works, drawing the water into itself by suction and forcing it out
through the connection pipe into the boiler by force of steam pressure
in the steam cylinder.

[Illustration: STRAIGHT GLOBE VALVE.]

[Illustration: ANGLE GLOBE VALVE.]

It is to be noted that all suction pumps receive their water by reason
of the pressure of the atmosphere on the surface of the water in the
supply tank or well. This atmospheric pressure is about 15 pounds to
the square inch, and is sufficient to support a column of water 28 to
33 feet high, 33 feet being the height of a column of water which the
atmosphere will support theoretically at about sea level. At greater
altitudes the pressure of the atmosphere decreases. Pumps do not work
very well when drawing water from a depth over 20 or 22 feet.

Water can be forced to almost any height by pressure of steam on the
plunger, and it is taken from deep wells by deep well pumps, which suck
the water 20 to 25 feet, and force it the rest of the way by pressure
on a plunger.

The amount of water pumped is regulated by a cock or globe valve in the
suction pipe.

A Cross-head boiler pump is a pump attached to the cross-head of an
engine. The force of the engine piston is transmitted to the plunger of
the pump.

The pump portion works exactly the same, whether of the independent or
cross-head kind.

The cut represents an independent pump that uses the exhaust steam to
heat the water as it is pumped (Marsh pump).

[Illustration: VALVE WITH INTERNAL SCREW.]

Every boiler feed-pump must have at least two check valves.

A check valve is a small swinging gate valve (usually) contained in a
pipe, and so arranged that when water is flowing in one direction the
valve will automatically open to let the water pass, while if water
should be forced in the other direction, the valve will automatically
close tight and prevent the water from passing.

[Illustration: SECTIONAL VIEW OF SWING CHECK VALVE.]

There is one check valve in the supply pipe which conducts the water
from the tank or well to the pump cylinder. When the plunger is drawn
back or raised, a vacuum is created in the pump cylinder and the
outside atmospheric pressure forces water through the supply pipe
into the cylinder, and the check valve opens to let it pass. When the
plunger returns, the check valve closes, and the water is forced into
the feed-pipe to the boiler.

[Illustration: SECTIONAL VIEW OF CASE HEATER.]

There are usually two check valves between the pump cylinder and the
boiler, both swinging away from the pump or toward the boiler. In
order that the water may flow steadily into the boiler there is an air
chamber, which may be partly filled with water at each stroke of the
plunger. As the water comes in, the air must be compressed, and as it
expands it forces the water through the feed pipe into the boiler in
a steady stream. There is one check valve between the pump cylinder
and the air chamber, to prevent the water from coming back into the
cylinder, and another between the air chamber and the boiler, to
prevent the steam pressure forcing itself or the water from the boiler
or water heater back into the air chamber.

[Illustration: SECTIONAL VIEW OF PENBERTHY INJECTOR.]

[Illustration: U. S. AUTOMATIC INJECTOR.

(American Injector Co.)]

All three of these check valves must work easily and fit tight if the
pump is to be serviceable. They usually close with rubber facings which
in time will get worn, and dirt is liable to work into the hinge and
otherwise prevent tight and easy closing. They can always be opened for
inspection, and new ones can be put in when the old are too much worn.

Only cold water can be pumped successfully, as steam from hot water
will expand, and so prevent a vacuum being formed. Thus no suction will
take place to draw the water from the supply source.

There should always be a globe valve or cock in the feed pipe near the
boiler to make it possible to cut out the check valves when the boiler
is under pressure. _It is never to be closed except_ when required for
this purpose.

Before passing into the boiler the water from the pump goes through the
_heater_. This is a small cylinder, with a coil of pipe inside. The
feed pipe from the pump is connected with one end of this inner coil of
pipe, while the other end of the coil leads into the boiler itself. The
exhaust steam from the engine cylinder is admitted into the cylinder
and passes around the coil of pipe, afterwards coming out of the smoke
stack to help increase the draft. As the feed water passes through this
heater it becomes heated nearly to boiling before it enters the boiler,
and has no tendency to cool the boiler off. Heating the feed water
results in an economy of about 10 per cent.

[Illustration: AUTOMATIC INJECTOR.]

_The Injector_ is another means of forcing water from a supply tank or
well into the boiler, and at the same time heating it, by use of steam
from the boiler. It is a necessity when a cross-head pump is used,
since such a pump will not work when the engine is shut down. It is
useful in any case to heat the water before it goes into the boiler
when the engine is not working and there is no exhaust steam for the
heater.

There are various types of injectors, but they all work on practically
the same principle. The steam from the boiler is led through a tapering
nozzle to a small chamber into which there is an opening from a water
supply pipe. This steam nozzle throws out its spray with great force
and creates a partial vacuum in the chamber, causing the water to flow
in. As the pressure of the steam has been reduced when it passes into
the injector, it cannot, of course, force its way back into the boiler
at first, and finds an outlet at the overflow. When the water comes in,
however, the steam jet strikes the water and is condensed by it. At the
same time it carries the water and the condensed steam along toward the
boiler with such force that the back pressure of the boiler is overcome
and a stream of heated water is passed into it. In order that the
injector may work, its parts must be nicely adjusted, and with varying
steam pressures it takes some ingenuity to get it started. Usually
the full steam pressure is turned on and the cock admitting the water
supply is opened a varying amount according to the pressure.

First the valve between the check valve and the boiler should be
opened, so that the feed water may enter freely; then open wide the
valve next the steam dome, and any other valve between the steam supply
pipe and the injector; lastly open the water supply valve. If water
appears at the overflow, close the supply valve and open it again,
giving it just the proper amount of turn. The injector is regulated by
the amount of water admitted.

[Illustration: PLAIN WHISTLE.]

In setting up an injector of any type, the following rules should be
observed:

All connecting pipes as straight and short as possible.

The internal diameter of all connecting pipes should be the same or
greater than the diameter of the hole in the corresponding part of the
injector.

When there is dirt or particles of wood or other material in the source
of water supply, the end of the water supply pipe should be provided
with a strainer. Indeed, invariably a strainer should be used. The
holes in this strainer must be as small as the smallest opening in the
delivery tube, and the total area of the openings in the strainer must
be much greater than the area of the water supply (cross-section).

The steam should be taken from the highest part of the dome, to avoid
carrying any water from the boiler over with it. Wet steam cuts and
grooves the steam nozzle. The steam should not be taken from the pipe
leading to the engine unless the pipe is quite large.

Before using new injectors, after they are fitted to the boiler it is
advisable to disconnect them and clean them out well by letting steam
blow through them or forcing water through. This will prevent lead or
loose scale getting into the injector when in use.

Set the injector as low as possible, as it works best with smallest
possible lift.

_Ejectors and jet pumps_ are used for lifting and forcing water by
steam pressure, and are employed in filling tanks, etc.


BLAST AND BLOW-OFF DEVICES.

In traction engines there is small pipe with a valve, leading into
the smoke stack from the boiler. When the valve is opened, the steam
allowed to blow off into the smoke stack will create a vacuum and so
increase the draft. Blast or blow pipes are used only in starting the
fire, and are of little value before the steam pressure reaches 15
pounds or so.

The exhaust nozzle from the engine cylinder also leads into the smoke
stack, and when the engine is running the exhaust steam is sufficient
to keep up the draft without using the blower.

_Blow-off cocks_ are used for blowing sediment out of the bottom of a
boiler, or blowing scum off the top of the water to prevent foaming. A
boiler should never be blown out at high pressure, as there is great
danger of injuring it. Better let the boiler cool off somewhat before
blowing off.


SPARK ARRESTER.

Traction engines are supplied as a usual thing with spark arresters if
they burn wood or straw. Coal sparks are heavy and have little life,
and with some engines no spark arrester is needed. But there is great
danger of setting a fire if an engine is run with wood or straw without
the spark arrester.

[Illustration: DIAMOND SPARK ARRESTER.]

Spark arresters are of different types. The most usual form is a large
screen dome placed over the top of the stack. This screen must be kept
well cleaned by brushing, or the draft of the engine will be impaired
by it.

In another form of spark arrester, the smoke is made to pass through
water, which effectually kills every possible spark.

The _Diamond Spark Arrester_ does not interfere with the draft and
is so constructed that all sparks are carried by a counter current
through a tube into a pail where water is kept. The inverted cone, as
shown in cut, is made of steel wire cloth, which permits smoke and gas
to escape, but no sparks. There is no possible chance to set fire to
anything by sparks. It is adapted to any steam engine that exhausts
into the smoke stack.




CHAPTER III.

THE SIMPLE ENGINE.


The engine is the part of a power plant which converts steam pressure
into power in such form that it can do work. Properly speaking,
the engine has nothing to do with generating steam. That is done
exclusively in the boiler, which has already been described.

[Illustration: VIEW OF SIMPLE CYLINDER.

(J. I. Case Threshing Machine Co.)]

The steam engine was invented by James Watt, in England, between 1765
and 1790, and he understood all the essential parts of the engine as
now built. It was improved, however, by Seguin, Ericsson, Stephenson,
Fulton, and many others.

Let us first consider:


THE STEAM CYLINDER, ITS PARTS AND CONNECTIONS.

The cylinder proper is constructed of a single piece of cast iron bored
out smooth.

The _cylinder heads_ are the flat discs or caps bolted to the ends of
the cylinder itself. Sometimes one cylinder head is cast in the same
piece with the engine frame.

The _piston_ is a circular disc working back and forth in the cylinder.
It is usually a hollow casting, and to make it fit the cylinder steam
tight, it is supplied on its circumference with _piston rings_. These
are made of slightly larger diameter than the piston, and serve as
springs against the sides of the cylinder. The _follower plate_ and
bolts cover the piston rings on the piston head and hold them in place.

[Illustration: CONNECTING ROD AND CROSS-HEAD.

(J. I. Case Threshing Machine Co.)]

The _piston rod_ is of wrought iron or steel, and is fitted firmly and
rigidly into the piston at one end. It runs from the piston through one
head of the cylinder, passing through a steam-tight “stuffing box.” One
end of the piston rod is attached to the cross-head.

The _cross-head_ works between _guides_, and has _shoes_ above and
below. It is practically a joint, necessary in converting straight back
and forth motion into rotary. The cross-head itself works straight back
and forth, just as the piston does, which is fastened firmly to one
end. At the other end is attached the _connecting rod_, which works on
a bearing in the cross-head, called the _wrist pin_, or cross-head pin.

The _connecting rod_ is wrought iron or steel, working at one end on
the bearing known as the wrist pin, and on the other on a bearing
called the _crank pin_.

The _crank_ is a short lever which transmits the power from the
connecting rod to the _crank shaft_. It may also be a disc, called the
_crank disc_.

[Illustration: CROSS-HEAD.

(J. I. Case Threshing Machine Co.)]

Let us now return to the steam cylinder itself.

The steam leaves the boiler through a pipe leading from the top of the
steam dome, and is let on or cut off by the _throttle_ valve, which is
usually opened and closed by some sort of lever handle. It passes on to
the _Steam-chest_, usually a part of the same casting as the cylinder.
It has a cover called the _steam-chest cover_, which is securely bolted
in place.

The _steam valve_, usually spoken of simply as the _valve_, serves
to admit the steam alternately to each end of the cylinder in such a
manner that it works the piston back and forth.

There are many kinds of valves, the simplest (shown in the diagram)
being the D-valve. It slides back and forth on the bottom of the
steam-chest, which is called the _valve seat_, and alternately opens
and closes the two _steam ports_, which are long, narrow passages
through which the steam enters the cylinder, first through one port
to one end, then through the other port to the other end. The exhaust
steam also passes out at these same ports.

The _exhaust chamber_ in the type of engine now under consideration is
an opening on the lower side of the valve, and is always open into the
_exhaust port_, which connects with the exhaust pipe, which finally
discharges itself through the _exhaust nozzle_ into the smoke stack of
a locomotive or traction engine, or in other types of engines, into the
_condenser_.

The valve is worked by the _valve stem_, which works through the valve
stem _stuffing-box_.

Of course the piston does not work quite the full length of the
cylinder, else it would pound against the cylinder heads.

The _clearance_ is the distance between the cylinder head at either end
and the piston when the piston has reached the limit of its stroke in
that direction.

In most engines the valve is so set that it opens a trifle just before
the piston reaches the limit of its movement in either direction, thus
letting some steam in before the piston is ready to move back. This
opening, which usually amounts to 1-32 to 3-16 of an inch, is called
the _lead_. The steam thus let in before the piston reaches the limit
of its stroke forms _cushion_, and helps the piston to reverse its
motion without any jar, in an easy and silent manner. Of course the
cushion must be as slight as possible and serve its purpose, else
it will tend to stop the engine, and result in loss of energy. Some
engines have no lead.

_Setting a valve_ is adjusting it on its seat so that the lead will
be equal at both ends and sufficient for the needs of the engine. By
shortening the movement of the valve back and forth, the lead can be
increased or diminished. This is usually effected by changing the
eccentric or valve gear.

The _lap_ of a slide valve is the distance it extends over the edges of
the ports when it is at the middle of its travel.

Lap on the steam side is called outside lap; lap on the exhaust side
is called inside lap. The object of lap is to secure the benefit of
working steam expansively. Having lap, the valve closes one steam port
before the other is opened, and before the piston has reached the end
of its stroke; also of course before the exhaust is opened. Thus for
a short time the steam that has been let into the cylinder to drive
the piston is shut up with neither inlet nor outlet, and it drives the
piston by its own expansive force. When it passes out at the exhaust it
has a considerably reduced pressure, and less of its force is wasted.

Let us now consider the


VALVE GEAR.

The mechanism by which the valve is opened and closed is somewhat
complicated, as various things are accomplished by it besides simply
opening and closing the valve. If an engine has a _reverse lever_, it
works through the valve gear; and the _governor_ which regulates the
speed of the engine may also operate through the valve gear. It is
therefore very important.

The simplest valve gear depends for its action on a fixed eccentric.

An _eccentric_ consists of a central disc called the _sheave_, keyed to
the main shaft at a point to one side of its true center, and a grooved
ring or _strap_ surrounding it and sliding loosely around it. The strap
is usually made of brass or some anti-friction metal. It is in two
parts, which are bolted together so that they can be tightened up as
the strap wears.

The _eccentric rod_ is either bolted to the strap or forms a single
piece with it, and this rod transmits its motion to the valve.

It will be seen, therefore, that the eccentric is nothing more than a
sort of disc crank, which, however, does not need to be attached to the
end of a shaft in the manner of an ordinary crank.

The distance between the center of the eccentric sheave and the
center of the shaft is called the _throw_ of the eccentric or the
_eccentricity_.

The eccentric usually conveys its force through a connecting rod to the
valve stem, which moves the valve.

The first modification of the simple eccentric valve gear is


THE REVERSING GEAR.

It is very desirable to control the movement of the steam valve, so
that if desired the engine may be run in the opposite direction; or the
steam force may be brought to bear to stop the engine quickly; or the
travel of the valve regulated so that it will let into the cylinder
only as much steam as is needed to run the engine when the load is
light and the steam pressure in the boiler high.

There is a great variety of reversing gears; but we will consider one
of the commonest and simplest first.

[Illustration: HUBER SINGLE ECCENTRIC REVERSE.]

If the eccentric sheave could be slipped around on the shaft to a
position opposite to that in which it was keyed to shaft in its
ordinary motion, the motion of the valve would be reversed, and it
would let steam in front of the advancing end of the piston, which
would check its movement, and start it in the opposite direction.

The _link gear_, invented by Stephenson, accomplishes this in a natural
and easy manner. There are two eccentrics placed just opposite to each
other on the crank shaft, their connecting rods terminating in what
is called a _link_, through which motion is communicated to the valve
stem. The link is a curved slide, one eccentric being connected to
one end, the other eccentric to the other end, and the _link-block_,
through which motion is conveyed to the valve, slides freely from one
end to the other. Lower the link so that the block is opposite the end
of the first rod, and the valve will be moved by the corresponding
eccentric; raise the link, so that the block is opposite the end of the
other rod, and the valve will be moved by the other eccentric. In the
middle there would be a dead center, and if the block stopped here, the
valve would not move at all. At any intermediate point, the travel of
the valve would be correspondingly shortened.

[Illustration: VALVE AND LINK REVERSE.]

Such is the theoretical effect of a perfect link; but the dead center
is not absolute, and the motion of the link is varied by the point
at which the rod is attached which lifts and lowers it, and also by
the length of this rod. In full gear the block is not allowed to come
quite to the end of the link, and this surplus distance is called the
_clearance_. The _radius_ of a link is the distance from the center of
the driving shaft to the center of the link, and the curve of the link
is that of a circle with that radius. The length of the radius may vary
considerably, but the point of suspension is important. If a link is
suspended by its center, it will certainly cut off steam sooner in the
front stroke than in the back. Usually it is suspended from that point
which is most used in running the engine.

[Illustration: THE WOOLF REVERSE VALVE GEAR.]

The _Woolf reversing gear_ employs but one eccentric, to the strap of
which is cast an arm having a block pivoted at its end. This block
slides in a pivoted guide, the angle of which is controlled by the
reverse lever. To the eccentric arm is attached the eccentric rod,
which transmits the motion to the valve rod through a rocker arm on
simple engines and through a slide, as shown in cut, on compound
engines.

_The Meyer valve gear_ does not actually reverse an engine, but
controls the admission of steam by means of an additional valve
riding on the back of the main valve and controlling the cut-off.
The main valve is like an ordinary D-valve, except that the steam is
not admitted around the ends, but through ports running through the
valve, these ports being partially opened or closed by the motion of
the riding valve, which is controlled by a separate eccentric. If
this riding valve is connected with a governor, it will regulate the
speed of an engine; and by the addition of a link the gear may be made
reversible. The chief objection to it is the excessive friction of the
valves on their seats.


GOVERNORS.

A governor is a mechanism by which the supply of steam to the cylinder
is regulated by revolving balls, or the like, which runs faster or
slower as the speed of the engine increases or diminishes. Thus the
speed of an engine is regulated to varying loads and conditions.

[Illustration: SECTIONAL VIEW SHOWING VALVE OF WATERS GOVERNOR.]

The simplest type of governor, and the one commonly used on traction
engines, is that which is only a modification of the one invented by
Watt. Two balls revolve around a spindle in such a way as to rise
when the speed of the engine is high, and fall when it is low, and in
rising and falling they open and close a valve similar to the throttle
valve. The amount that the governor valve is opened or closed by the
rise and fall of the governor balls is usually regulated by a thumb
screw at the top or side, or by what is called a handle nut, which is
usually held firm by a check nut directly over it, which should be
screwed firm against the handle nut. Motion is conveyed to the governor
balls by a belt and a band wheel working on a mechanism of metred cogs.

There is considerable friction about a governor of this type and much
energy is wasted in keeping it going. The valve stem or spindle passes
through a steam-tight stuffing box, where it is liable to stick if the
packing is too tight; and if this stuffing box leaks steam, there will
be immediate loss of power.

[Illustration: PICKERING HORIZONTAL GOVERNOR.]

Such a governor as has just been described is called a throttle valve
governor. On high grade engines the difficulties inherent in this type
of governor are overcome by making the governor control, not a valve in
the steam supply pipe, but the admission of steam to the steam cylinder
through the steam valve and its gear. Such engines are described as
having an “automatic cut-off.” Sometimes the governor is attached to
the link, sometimes to a separate valve, as in the Meyer gear already
described. Usually the governor is attached to the fly-wheel, and
consequently governors of this type are called fly-wheel governors.
An automatic cut-off governor is from 15 per cent to 20 per cent more
effective than a throttle valve governor.


CRANK, SHAFT AND JOURNALS.

We have already seen how the piston conveys its power through the
piston rod, the cross-head, and the connecting rod, to the crank pin
and crank, and hence to the shaft.

_The key, gib, and strap_ are the effective means by which the
connecting rod is attached, first to the wrist pin in the cross-head,
and secondly to the crank pin on the crank.

The _strap_ is usually made of two or three pieces of wrought iron or
steel bolted together so as to hold the _brasses_, which are in two
parts and loosely surround the pin. The brasses do not quite meet, and
as they wear may be tightened up. This is effected by the _gib_, back
of which is the _key_, which is commonly a wedge which may be driven
in, or a screw, which presses on the back of the gib, which in turn
forces together the brasses; and thus the length of the piston gear is
kept uniform in spite of the wear, becoming neither shorter nor longer.
When the brasses are so worn that they have been forced together, they
must be taken out and filed equally on all four of the meeting ends,
and shims, or thin pieces of sheet iron or the like placed back of them
to equalize the wear, and prevent the piston gear from being shortened
or otherwise altered.

[Illustration: CONNECTING ROD AND BOXES.

(A. W. Stevens Co.)]

The _crank_ is a simple lever attached to the shaft by which the shaft
is rotated. There are two types of crank in common use, the side crank,
which works by what is virtually a bend in the shaft. There is also
what is called the disc crank, a variation of the side crank, in which
the power is applied to the circumference of a disc instead of to the
end of a lever arm.

The _boss_ of a crank is that part which surrounds the shaft and butts
against the main bearing, and is usually about twice the diameter of
the crank shaft journal. The _web_ of the crank is the portion between
the shaft and the pin.

To secure noiseless running, the crank pin should be turned with great
exactness, and should be set exactly parallel with the direction of the
shaft. When the pressure on the pin or any bearing is over 800 pounds
per square inch, oil is no longer able to lubricate it properly. Hence
the bearing surface should always be large enough to prevent a greater
pressure than 800 pounds to the square inch. To secure the proper
proportions the crank pin should have a diameter of one-fourth the
bore of the cylinder, and its length should be one-third that of the
cylinder.

The _shaft_ is made of wrought iron or steel, and must not only be able
to withstand the twisting motion of the crank, but the bending force of
the engine stroke. To prevent bending, the shaft should have a bearing
as near the crank as possible.

The _journals_ are those portions of the shaft which work in bearings.
The main bearings are also called _pedestals_, _pillow blocks_, and
_journal boxes_. They usually consist of boxes made of brass or some
other anti-friction material carried in iron pedestals. The pillow
blocks are usually adjustable.


THE FLY-WHEEL.

This is a heavy wheel attached to the shaft. Its object is to regulate
the variable action of the piston, and to make the motion uniform even
when the load is variable. By its inertia it stores energy, which would
keep the engine running for some time after the piston ceased to apply
any force or power.


LUBRICATORS.

All bearings must be steadily and effectively lubricated, in order
to remove friction as far as possible, or the working power of the
engine will be greatly reduced. Besides, without complete and effective
lubrication, the bearings will “cut,” or wear in irregular grooves,
etc., quickly ruining the engine.

Bearings are lubricated through automatic lubricator cups, which hold
oil or grease and discharge it uniformly upon the bearing through a
suitable hole.

[Illustration: THE “DETROIT” ZERO DOUBLE CONNECTION LUBRICATOR.

DESCRIPTION.

  C 1--Body or Oil Reservoir.
  C 3--Filler Plug.
  C 4--Water Valve.
  C 5--Plug for inserting Sight-Feed Glass.
  C 6--Sight-Feed Drain Stem.
  C 7--Regulating Valve.
  C 8--Drain Valve.
  C 9--Steam Valve.
  C10--Union Nut.
  C11--Tail Piece.
    H--Sight-Feed Glass.]

A sight feed ordinary cup permits the drops of oil to be seen as they
pass downward through a glass tube, and also the engineer may see how
much oil there is in the cup. Such a cup is suitable for all parts
of an engine except the crank pin, cross-head, and, of course, the
cylinder.

The crank pin oiler is an oil cup so arranged as to force oil into
the bearing only when the engine is working, and more rapidly as the
engine works more rapidly. In one form, which uses liquid oil, the oil
stands below a disc, from which is the opening through the shank to the
bearing. As the engine speeds up, the centrifugal force tends to force
the oil to the top of the cup and so on to the bearing, and the higher
the speed the greater the amount of oil thrown into the crank pin.

Hard oil or grease has of late been coming into extensive use. It is
placed in a compression cup, at the top of which a disc is pressed down
by a spring, and also by some kind of a screw. From time to time the
screw is tightened up by hand, and the spring automatically forces down
the grease.

[Illustration: GLASS OIL CUP.]

[Illustration: SECTIONAL VIEW IDEAL GREASE CUP.]

_The Cylinder Lubricator_ is constructed on a different principle,
and uses an entirely different kind of oil, called “cylinder oil.” A
sight-feed automatic oiler is so arranged that the oil passes through
water drop by drop, so that each drop can be seen behind glass before
it passes into the steam pipe leading from the boiler to the cylinder.
The oil mingles with the steam and passes into the steam chest, and
thence into the cylinder, lubricating the valve and piston.

The discharge of the oil may not only be watched, but regulated, and
some judgment is necessary to make sure that enough oil is passing into
the cylinder to prevent it from cutting.

The oil is forced into the steam by the weight of the column of
water, since the steam pressure is the same at both ends. There is a
small cock by which this water of condensation may be drained off when
the engine is shut down in cold weather. Oilers are also injured by
straining from heating caused by the steam acting on cold oil when all
the cocks are closed. There is a relief cock to prevent this strain,
and it should be slightly opened, except when oiler is being filled.

[Illustration: ACORN OIL PUMP.]

There are a number of different types of oilers, with their cocks
arranged in different ways; but the manufacturer always gives diagrams
and instructions fully explaining the working of the oiler. Oil pumps
serving the same purpose are now often used.


DIFFERENTIAL GEAR.

The gearing by which the traction wheels of a traction engine are made
to drive the engine is an important item. Of course, it is desirable to
apply the power of the engine to both traction wheels; yet if both hind
wheels were geared stiff, the engine could not turn from a straight
line, since in turning one wheel must move faster than the other. The
differential or compensating gear is a device to leave both wheels free
to move one ahead of the other if occasion requires. The principle is
much the same as in case of a rachet on a geared wheel, if power were
applied to the ratchet to make the wheel turn; if for any reason the
wheel had a tendency of its own to turn faster than the ratchet forced
it, it would be free to do so. When corners are turned the power is
applied to one wheel only, and the other wheel is permitted to move
faster or slower than the wheel to which the gearing applies the power.

There are several forms of differential gears, differing largely as
to combination of spur or bevel cogs. One of the best known uses four
little beveled pinions, which are placed in the main driving wheel as
shown in the cut. Beveled cogs work into these on either side of the
main wheel. If one traction wheel moves faster than the other these
pinions move around and adjust the gears on either side.

[Illustration: THE HUBER SPUR COMPENSATING GEAR.]

[Illustration: AULTMAN & TAYLOR BEVEL COMPENSATING GEAR.]

[Illustration: DIFFERENTIAL GEAR, SHOWING CUSHION SPRINGS AND BEVEL
PINION.]


FRICTION CLUTCH.

The power of an engine is usually applied to the traction wheel by a
friction clutch working on the inside of the fly-wheel. (See plan of
Frick Engine.) The traction wheels are the two large, broad-rimmed hind
wheels, and are provided with projections to give them a firm footing
on the road. Traction engines are also provided with mud shoes and
wheel cleaning devices for mud and snow.

[Illustration: THE FRICK COMPANY TRACTION ENGINE.

Plan view of “Eclipse” Traction Engine, showing arrangement of Patent
Reverse Gear and Friction Clutch for Driving Pinion.]


THE FUSIBLE PLUG.

The fusible plug is a simple screw plug, the center of which is bored
out and subsequently filled with some other metal that will melt at a
lower temperature than steel or iron. This plug is placed in the crown
sheet of a locomotive boiler as a precaution for safety. Should the
crown sheet become free of water when the fire is very hot, the soft
metal in the fusible plug would melt and run out, and the overheated
steam would escape into the firebox, putting out the fire and giving
the boiler relief so that an explosion would be avoided. In some states
a fusible plug is required by law, and one is found in nearly every
boiler which has a crown sheet. Return flue boilers and others which do
not have crown sheets (as for example the vertical) do not have fusible
plugs. To be of value a fusible plug should be renewed or changed once
a month.


STUFFING BOXES.

Any arrangement to make a steam-tight joint about a moving rod, such
as a piston rod or steam valve rod, would be called a stuffing box.
Usually the stuffing box gives free play to a piston rod or valve rod,
without allowing any steam to escape. A stuffing box is also used on
a pump piston sometimes, or a compressed air piston. In all these
cases it consists of an annular space around the moving rod which
can be partly filled by some pliable elastic material such as hemp,
cotton, rubber, or the like; and this filling is held in place and made
tighter or looser by what is called a gland, which is forced into the
partly filled box by screwing up a cap on the outside of the cylinder.
Stuffing boxes must be repacked occasionally, since the packing
material will get hard and dead, and will either leak steam or cut the
rod.


CYLINDER COCKS.

These cocks are for the purpose of drawing the water formed by
condensation of steam out of the cylinder. They should be opened
whenever the engine is stopped or started, and should be left open when
the engine is shut down, especially in cold weather to prevent freezing
of water and consequent damage. Attention to these cocks is very
important.

These are small cocks arranged about the pump and at other places for
the purpose of testing the inside action. By them it is possible to see
if the pump is working properly, etc.


STEAM INDICATOR.

The steam indicator is an instrument that can be attached to either
end of a steam cylinder, and will indicate the character of the steam
pressure during the entire stroke of the piston. It shows clearly
whether the lead is right, how much cushion there is, etc. It is very
important in studying the economical use and distribution of steam,
expansive force of steam, etc.


LIST OF ATTACHMENTS FOR TRACTION ENGINE AND BOILER.

The following list of brasses, etc., which are packed with the Case
traction engine will be useful for reference in connection with any
similar traction engine and boiler. The young engineer should rapidly
run over every new engine and locate each of these parts, which will be
differently placed on different engines:

  1 Steam Gauge with siphon.
  1 Safety Valve.
  1 Large Lubricator.
  1 Small Lubricator for Pump.
  1 Glass Water Gauge complete with glass and rods.
  2 Gauge Cocks.
  1 Whistle.
  1 Injector Complete.
  1 Globe Valve for Blow-off.
  1 Compression Grease Cup for Cross Head.
  1 Grease Cup for Crank Pin.
  1 Oiler for Reverse Block.
  1 Glass Oiler for Guides.
  1 Small Oiler for Eccentric Rod.
  1 Cylinder Cock (1 is left in place.)
  2 Stop Cocks to drain Heater.
  1 Stop Cock for Hose Coupling on Pump.
  1 Bibb Nose Cock for Pump.
  1 Pet Cock for Throttle.
  2 Pet Cocks for Steam Cylinder of Pump.
  1 Pet Cock for Water Cylinder of Pump.
  1 Pet Cock for Feed Pipe from Pump.
  1 Pet Cock for Feed Pipe from Injector.
  1 Governor Belt.
  1 Flue Cleaner.
  15 ft. 1 in. Suction Hose.
  5 ft. Sprinkling Hose.
  1 Strainer for Suction Hose.
  1 Strainer for Funnel.
  4 ft. 6 in. of in. Hose for Injector.
  5 ft. 6 in. of in. Hose for Pump.
  2 Nipples ¾×2½ in. for Hose.
  2 ¾ in. Hose Clamps.
  2 ½ in. Hose Strainers.


TEST QUESTIONS ON BOILER AND ENGINE

Q. How is the modern stationary fire-flue boiler arranged?

Q. How does the locomotive type of boiler differ?

Q. What is a return flue boiler?

Q. What is a water-tube boiler and how does it differ from a fire-flue
tubular boiler?

Q. What is a vertical boiler and what are its advantages?

Q. What is the shell?

Q. What are the boiler heads?

Q. What are the tube sheets?

Q. What is the firebox?

Q. What is the water leg?

Q. What is the crown-sheet?

Q. Where is the smoke-box located?

Q. What is the steam dome intended for?

Q. What is the mud-drum for?

Q. What are man-holes and hand-holes for?

Q. What is a boiler jacket?

Q. What is a steam jacket?

Q. Where is the ash-pit?

Q. What are dead-plates?

Q. How is grate surface measured?

Q. What is forced draft?

Q. How is heating surface measured?

Q. What is steam space?

Q. What is water space?

Q. What is a diaphragm plate?

Q. What is the first duty of an engineer in taking charge of a new
boiler?

Q. What are the water gauge and try cocks for, and how are they placed?

Q. What is the steam gauge and how may it be tested?

Q. What is a safety valve? Should it be touched by the engineer? How
may he test it with the steam gauge?

Q. How is a boiler first filled with water?

Q. How is it filled when under pressure?

Q. What is an independent pump? What is a crosshead pump?

Q. What is a check valve, and what is its use, and where located?

Q. What is a heater and how does it work?

Q. What is an injector, and what is the principle of its operation?

Q. Where are the blow-off cocks located? How should they be used?

Q. In what cases should spark arrester be used?

Q. Who invented the steam engine, and when?

Q. What are the essential parts of a steam engine?

Q. What is the cylinder, and how is it used?

Q. What is the piston, and how does it work? The piston-rings?

Q. What is the piston rod and how must it be fastened?

Q. What is the crosshead, and how does it move? What are guides or
ways? Shoes?

Q. What is the connecting rod? Wrist pin? Crank pin?

Q. What is the crank? Crank shaft?

Q. Where is the throttle valve located, and what does opening and
closing it do?

Q. What is the steam chest for, and where is it placed?

Q. What is a steam valve? Valve seats? Ports?

Q. What is the exhaust? Exhaust chamber? Exhaust port? Exhaust nozzle?
What is a condenser?

Q. How is the valve worked, and what duties does it perform, and how?

Q. What is clearance?

Q. What is lead?

Q. What is cushion?

Q. How would you set a valve? What is lap?

Q. How is a steam valve moved back and forth in its seat?

Q. How may an engine be reversed?

Q. What is a governor, and how does it work?

Q. What is an eccentric? Eccentric sheave? Strap? Rod?

Q. What is the throw of an eccentric?

Q. How does the link reversing gear work?

Q. How does the Woolf reverse gear work?

Q. How does the Meyer valve gear work? Will it reverse an engine?

Q. What are the chief difficulties in the working of a governor?

Q. What are key, gib, and strap? Brasses?

Q. What is the boss of a crank? Web?

Q. How may noiseless running of a crank be secured?

Q. What are journals? Pedestals? Pillow blocks? Journal boxes?

Q. What is the object in having a fly wheel?

Q. What different kinds of lubricators are there? Where may hard oil or
grease be used? Is the oil used for lubricating the cylinder the same
as that used for rest of the engine?

Q. How does a cylinder lubricator work?

Q. What is differential gear, and what is it for?

Q. What is the use of a fusible plug, and how is it arranged?

Q. What are stuffing-boxes, and how are they constructed?

Q. What are cylinder cocks, and what are they used for?

Q. What are pet cocks?

Q. What is a steam indicator?




CHAPTER IV.

HOW TO MANAGE A TRACTION ENGINE BOILER.


We will suppose that the young engineer fully understands all parts of
the boiler and engine, as explained in the preceding chapters. It is
well to run over the questions several times, to make sure that every
point has been fully covered and is well understood.

We will suppose that you have an engine in good running order. If you
have a new engine and it starts off nice and easy (the lone engine
without load) with twenty pounds steam pressure in the boiler, you may
make up your mind that you have a good engine to handle and one that
will give but little trouble. But if it requires fifty or sixty pounds
to start it, you want to keep your eyes open, for something is tight.
But don’t begin taking the engine to pieces, for you might get more
pieces than you know what to do with. Oil every bearing fully, and
then start your engine and let it run for a while. Then notice whether
you find anything getting warm. If you do, stop and loosen up a very
little and start again. If the heating still continues, loosen again as
before. But remember, loosen but little at a time, for a box or journal
will heat from being too loose as quickly as from being too tight,
and if you have found a warm box, don’t let that box take all your
attention, but keep your eye on the other bearings.

In the case of a new engine, the cylinder rings may be a little tight,
and so more steam pressure will be required to start the engine; but
this is no fault, for in a day or two they will be working all right if
kept well oiled.

In starting a new engine trouble sometimes comes from the presence of a
coal cinder in some of the boxes, which has worked in during shipment.
Before starting a new engine, the boxes and oil holes should therefore
be thoroughly cleaned out. For this purpose the engineer should always
have some cotton waste or an oiled rag ready for constant use.

A new engine should be run slowly and carefully until it is found to be
in perfect running order.

If you are beginning on an old engine in good running order, the above
instructions will not be needed; but it is well to take note of them.

Now if your engine is all right, you may run the pressure up to the
point of blowing off, which is 100 to 130 pounds, at which most safety
valves are set at the factory. It is not uncommon for a new pop to
stick, and as the steam runs up it is well to try it by pulling the
relief lever. If on letting it go it stops the escaping steam at once,
it is all right. If, however, the steam continues to escape the valve
sticks in the chamber. Usually a slight tap with a wrench or hammer
will stop it at once; but don’t get excited if the steam continues to
escape. As long as you have plenty of water in the boiler, and know
that you have it, you are all right.


STARTING UP A BOILER.

Almost the only danger from explosion of a boiler is from not having
sufficient water in the boiler. The boiler is filled in the first
place, as has already been explained, by hand through a funnel at the
filler plug, or by a force pump. The water should stand an inch and
a half in the glass of the water gauge before the fire is started.
It should be heated up slowly so as not to strain the boiler or
connections. When the steam pressure as shown by the steam gauge is ten
or fifteen pounds, the blower may be used to increase the draft.

If you let the water get above the top of the glass, you are liable
to knock out a cylinder head; and if you let the water get below the
bottom of the glass, you are likely to explode your boiler.

The glass gauge is not to be depended upon, however, for a number
of things may happen to interfere with its working. Some one may
inadvertently turn off the gauge cocks, and though the water stands at
the proper height in the glass, the water in the boiler will be very
different.

A properly made boiler is supplied with two to four try-cocks, one
below the proper water line, and one above it. If there are more than
two they will be distributed at suitable points between.

When the boiler is under pressure, turn on the lower try-cock and you
should get water. You will know it because it will appear as white
mist. Then try the upper try-cock, and you will get steam, which will
appear blue.

NEVER FAIL TO USE THE TRY-COCKS FREQUENTLY. This is necessary not only
because you never know when the glass is deceiving you; but if you fail
to use them they will get stopped up with lime or mud, and when you
need to use them they will not work.

In order also to keep the water gauge in proper condition, it should
be frequently blown out in the following manner: Shut off the top
gauge cock and open the drain cock at the bottom of the gauge. This
allows the water and steam to blow through the lower cock of the water
gauge, and you know that it is open. Any lime or mud that has begun
to accumulate will also be carried off. After allowing the steam to
escape a few seconds, shut off the lower gauge cock, and open the upper
one, and allow it to blow off about the same time. Then shut the drain
cock and open both gauge cocks, when you will see the water seek its
level, and you can feel assured that it is reliable and in good working
condition. This little operation you should perform every day you run
your engine. If you do you will not _think_ you have sufficient water
in the boiler, but will _know_. The engineer who always _knows_ he has
water in the boiler will not be likely to have an explosion. Especially
should you never start your fire in the morning simply because you see
water in the gauge. You should _know_ that there is water in the boiler.

Now if your pump and boiler are in good working condition, and you
leave the globe valve in the supply pipe to the pump open, with the
hose in the tank, you will probably come to your engine in the morning
and find the boiler nearly full of water, and you will think some one
has been tampering with the engine. The truth is, however, that as
the steam condensed, a vacuum was formed, and the water flowed in on
account of atmospheric pressure, just as it flows into a suction pump
when the plunger rises and creates a vacuum in the pump. Check valves
are arranged to prevent anything passing out of the boiler, but there
is nothing to prevent water passing in.

The only other cause of an explosion, beside poor material in the
manufacture of the boiler, is too high steam pressure, due to a
defective safety valve or imperfect steam gauge. The steam gauge is
likely to get out of order in a number of ways, and so is the safety
valve. To make sure that both are all right, the one should frequently
be tested by the other. The lever of the safety valve should frequently
be tried from time to time, to make sure the valve opens and closes
easily, and whenever the safety valve blows off, the steam gauge should
be noted to see if it indicates the pressure at which the safety has
been set.


WHEN YOUR ENGINE IS ALL RIGHT, LET IT ALONE.

Some engineers are always loosening a nut here, tightening up a box
there, adjusting this, altering that. When an engine is all right
they keep at it till it is all wrong. As a result they are in trouble
most of the time. When an engine is running all right, LET IT ALONE.
Don’t think you are not earning your salary because you are merely
sitting still and looking on. If you must be at work, keep at it with
an oily rag, cleaning and polishing up. That is the way to find out if
anything is really the matter. As the practised hand of the skilled
engineer goes over an engine, his ears wide open for any peculiarity of
sound, anything that is not as it should be will make itself decidedly
apparent. On the other hand, an engineer who does not keep his engine
clean and bright by constantly passing his hand over it with an oily
rag, is certain to overlook something, which perhaps in the end will
cost the owner a good many dollars to put right.

Says an old engineer[3] we know, “When I see an engineer watching
his engine closely while running, I am most certain to see another
commendable feature in a good engineer, and that is, when he stops his
engine he will pick up a greasy rag and go over his engine carefully,
wiping every working part, watching or looking carefully at every point
that he touches. If a nut is working loose, he finds it; if a bearing
is hot, he finds it; if any part of his engine has been cutting,
he finds it. He picks up a greasy rag instead of a wrench, for the
engineer that understands his business and attends to it never picks up
a wrench unless he has something to do with it.”

  Footnote 3: J. H. Maggard, author of “Rough and Tumble Engineering,”
    to whom we are indebted for a number of valuable suggestions in
    this chapter.

This same engineer goes on with some more most excellent advice. Says
he:

“Now, if your engine runs irregularly, that is, if it runs up to a
higher speed than you want, and then runs down, you are likely to say
at once, ‘Oh, I know what the trouble is, it is the governor.’ Well,
suppose it is. What are you going to do about it? Are you going to
shut down at once and go to tinkering with it? No, don’t do that. Stay
close to the throttle valve and watch the governor closely. Keep your
eye on the governor stem, and when the engine starts off on one of its
speed tilts, you will see the stem go down through the stuffing box
and then stop and stick in one place until the engine slows down below
its regular speed, and it then lets loose and goes up quickly and your
engine lopes off again. You have now located the trouble. It is in the
stuffing box around the little brass rod or governor stem. The packing
has become dry and by loosening it up and applying oil you may remedy
the trouble until such time as you can repack it with fresh packing.
Candle wick is as good for this purpose as anything you can use.

“But if the governor does not act as I have described, and the stem
seems to be perfectly free and easy in the box, and the governor still
acts queerly, starting off and running fast for a few seconds and then
suddenly concluding to take it easy and away goes the engine again,
see if the governor belt is all right, and if it is it would be well
for you to stop and see if a wheel is not loose. It might be either
the little belt wheel or one of the little cog wheels. If you find
these are all right, examine the spool on the crank shaft from which
the governor is run, and you will probably find it loose. If the
engine has been run for any length of time, you will always find the
trouble in one of these places; but if it is a new one, the governor
valve might work a little tight in the valve chamber, and you may have
to take it out and use a little emery paper to take off the rough
projections on the valve. Never use a file on this valve if you can get
emery paper, and I should advise you always to have some of it with
you. It will often come handy.”

This is good advice in regard to any trouble you may have with an
engine. Watch the affected part closely; think the matter over
carefully, and see if you cannot locate the difficulty before you even
stop your engine. If you find the trouble and know that you have found
it, you will soon be able to correct the defect, and no time will be
lost. At the same time you will not ruin your engine by trying all
sorts of remedies at random in the thought that you may ultimately
hit the right thing. The chances are that before you do hit the right
point, you will have put half a dozen other matters wrong, and it will
take half a day to get the matter right again.

As there are many different types of governors in use, it would be
impossible to give exact directions for regulating that would apply to
them all; but the following suggestions applying to the Waters governor
(one widely used on threshing engines) will give a general idea of the
method for all:

There are two little brass nuts on the top of the stem of the governor,
one a thumb nut and the other a loose jam nut. To increase the speed,
loosen the jam nut and then turn the thumb nut back slowly, watching
the motion of the engine all the time. When the required speed has
been obtained, then tighten up as snug as you can with your fingers
(not using a wrench). To decrease the speed, loosen the jam nut as
before, running it up a few turns, and then turn down the thumb nut
till the speed meets your requirements, when the thumb nut is made fast
as before. In any case, be very careful not to press down on the stem
when turning the thumb nut, as this will make the engine run a little
slower than will be the case when your hand has been removed.

If your engine does not start with an open throttle, look to see if
the governor stem has not been screwed down tight. This is usually
the case with a new engine, which has been screwed down for safety in
transportation.


WATER FOR THE BOILER.

There is nothing that needs such constant watching and is likely to
cause so much trouble if it is not cared for, as the supply of water.
Hard well water will coat the inside of the boiler with lime and soon
reduce its steaming power in a serious degree, to say nothing of
stopping up pipes, cocks, etc. At the same time, rain water that is
perfectly pure (theoretically) will be found to have a little acid
or alkali in it that will eat through the iron or steel and do equal
damage.

However, an engineer must use what water he can. He cannot have it
made to order for him, but he must take it from well, from brook, or
cistern, or roadside ditch, as circumstances may require. The problem
for the engineer is not to get the best water, but to make the best use
of whatever water he can get, always, of course, choosing the best and
purest when there is such a thing as choosing.

In the first place, all supply pipes in water that is muddy or likely
to have sticks, leaves, or the like in it, should be furnished with
strainers. If sticks or leaves get into the valve, the expense in time
and worry to get them out will be ten times the cost of a strainer.

If the water is rain water, and the boiler is a new one, it would be
well to put in a little lime to give the iron a slight coating that
will protect it from any acid or alkali corrosion.

If the water is hard, some compound or sal ammonia should be used.
No specific directions can be given, since water is made hard by
having different substances dissolved in it, and the right compound or
chemical is that which is adapted to the particular substance you are
to counteract. An old engineer says his advice is to use no compound
at all, but to put a hatful of potatoes in the boiler every morning.

Occasionally using rain water for a day or two previous to cleaning is
one of the best things in the world to remove and throw down all scale.
It beats compounds at every point. It is nature’s remedy for the bad
effects of hard water.

The important thing, however, is to clean the boiler thoroughly and
often. In no case should the lime be allowed to bake on the iron. If it
gets thick, the iron or steel is sure to burn, and the lime to bake so
hard it will be almost impossible to get it off. But if the boiler is
cleaned often, such a thing will not happen.

Mud or sediment can be blown off by opening the valve from the mud drum
or the firebox at the bottom of the boiler when the pressure is not
over 15 or 20 pounds; and at this pressure much of the lime distributed
about the boiler may be blown off. But this is not enough. The inside
of the boiler should be scraped and thoroughly washed out with a hose
and force-pump just as often as the condition of the water requires it.

In cleaning the boiler, always be careful to scrape all the lime off
the top of the fusible plug.


THE PUMP.

In order to manage the pump successfully, the young engineer must
understand thoroughly its construction as already described. It is
also necessary to understand something of the theory of atmospheric
pressure, lifting power, and forcing power.

First see that the cocks or globe valves (whichever are used) are
open both between the boiler and the pump and between the pump and
the water supply. The globe valve next the boiler should _never_ be
closed, except when examining the boiler check valve. Then open the
little pet cock between the two upper horizontal check valves. Be sure
that the check valves are in good order, so that water can pass only
in one direction. A clear, sharp click of the check valves is certain
evidence that the pump is working well. If you cannot hear the click,
take a stick or pencil between your teeth at one end, put the other
end on the valve, stuff your fingers in your ears, and you will hear
the movement of the valve as plainly as if it were a sledge-hammer.

The small drain cock between the horizontal check valves is used to
drain hot water out of the pump in starting, for a pump will never work
well with hot water in it; and to drain off all water in closing down
in cold weather, to prevent damage from freezing. It also assists in
testing the working of the pump. In starting up it may be left open. If
water flows from the drain cock, we know the pump is working all right,
and then close the drain cock. If you are at any time in doubt as to
whether water is going into the boiler properly, you may open this
drain cock and see if cold water flows freely. If it does, everything
is working as it should. If hot water appears, you may know something
is wrong. Also, to test the pump, place your hand on the two check
valves, and if they are cold, the pump is all right; if they are hot,
something is wrong, since the heat must come from the boiler, and no
hot water or steam should ever be allowed to pass from the boiler back
to the pump.

A stop cock next the boiler is decidedly preferable to a globe valve,
since you can tell if it is open by simply looking at it; whereas you
must put your hand on a globe valve and turn it. Trouble often arises
through inadvertently closing the valve or cock next the boiler, in
which case, of course, no water can pass into the boiler, and the pump
is likely to be ruined, since the water must get out somewhere. Some
part of the pump would be sure to burst if worked against a closed
boiler cock or valve.

Should the pump suddenly cease to work or stop, first see if you have
any water in the tank. If there is water, stoppage may be due to air in
the pump chamber, which can get in only through the stuffing-box. If
this is true, tighten up the pump plunger stuffing-box nut a little. If
now the pump starts off well, you have found the difficulty; but at the
first opportunity you ought to repack the stuffing-box.

If the stuffing-box is all right, examine the supply suction hose. See
that nothing is clogging the strainer, and ascertain whether the water
is sucked in or not. If it is sucked in and then is forced out again
(which you can ascertain by holding your hand lightly over the suction
pipe), you may know something is the matter with the first check valve.
Probably a stick or stone has gotten into it and prevents it from
shutting down.

If there is no suction, examine the second check valve. If there is
something under it that prevents its closing, the water will flow back
into the pump chamber again as soon as the plunger is drawn back.

You can always tell whether the trouble is in the second check or in
the hot water check valve by opening the little drain cock. If hot
water flows from it, you may know that the hot water check valve is
out of order; if only cold water flows, you may be pretty sure the hot
water check is all right. If there is any reason to suspect the hot
water check valve, close the stop cock or valve next the boiler before
you touch the check in any way. To tamper with the hot water check
while the steam pressure is upon it would be highly dangerous, for you
are liable to get badly burned with escaping steam or hot water. At the
same time, be very sure the stop cock or valve next the boiler is open
again before you start the pump.

Another reason for check valves refusing to work besides having
something under them, is that the valve may stick in the valve chamber
because of a rough place in the chamber, or a little projection on
the valve. Light tapping with a wrench may remedy the matter. If that
does not work, try the following plan suggested by an old engineer[4]:
“Take the valve out, bore a hole in a board about one-half inch deep,
and large enough to permit the valve to be turned. Drop a little emery
dust in this hole. If you haven’t any emery dust, scrape some grit from
a whetstone. If you have no whetstone, put some fine sand or gritty
soil in the hole, put the valve on top of it, put your brace on the
valve and turn it vigorously for a few minutes, and you will remove all
roughness.”

  Footnote 4: J. H. Maggard.

Sometimes the burr on the valve comes from long use; but the above
treatment will make it as good as new.


INJECTORS.

All injectors are greatly affected by conditions, such as the lift, the
steam pressure, the temperature of the water, etc. An injector will
not use hot water well, if at all. As the lift is greater, the steam
pressure required to start is greater, and at the same time the highest
steam pressure under which the injector will work at all is greatly
decreased. The same applies to the lifting of warm water: the higher
the temperature, the greater the steam pressure required to start, and
the less the steam pressure which can be used as a maximum.

It is important for the sake of economy to use the right sized
injector. Before buying a new injector, find out first how much water
you need for your boiler, and then buy an injector of about the
capacity required, though of course an injector must always have a
maximum capacity in excess of what will be required.

If the feed water is cold, a good injector ought to start with 25
pounds steam pressure and work up to 150 pounds for a 2-foot lift. If
the lift is eight feet, it will start at 30 pounds and work up to 130.
If the water is heated to 100 degrees Fahrenheit it will start for a
2-foot lift with 26 pounds and work up to 120 pounds, or for an 8-foot
lift, it will start with 33 pounds and work up to 100. These figures
apply to the single tube injector. The double tube injector should work
from 14 pounds to 250, and from 15 to 210 under same conditions as
above. The double tube injector is not commonly used on farm engines,
however.

Care should be taken that the injector is not so near the boiler as to
become heated, else it will not work. If it gets too hot, it must be
cooled by pouring cold water on the outside, first having covered it
with a cloth to hold the water. If the injector is cool, and the steam
pressure and lift are all right, and still the injector does not work,
you may be sure there is some obstruction somewhere. Shut off the steam
from the boiler, and run a fine wire down through the cone valve or
cylinder valve, after having removed the cap or plug nut.

Starting an injector always requires some skill, and injectors differ.
Some start by manipulating the steam valve; some require that the steam
be turned on first, and then the water turned on in just the right
amount, usually with a quick short twist of the supply valve. Often
some patience is required to get just the right turn on it so that it
will start.

Of course you must be sure that all joints are air-tight, else the
injector will not work under any conditions.

Never use an injector where a pump can be used, as the injector is much
more wasteful of steam. It is for an emergency or to throw water in a
boiler when engine is not running.

No lubricator is needed on an injector.


THE HEATER.

The construction of the heater has already been explained. It has two
check valves, one on the side of the pump and one on the side of the
boiler, both opening toward the boiler. The exhaust steam is usually at
a temperature of 215 to 220 degrees when it enters the heater chamber,
and heats the water nearly or quite to boiling point as it passes
through. The injector heats the water almost as hot.

The heater requires little attention, and the check valves seldom get
out of order.

The pump is to be used when the engine is running, and the injector
when the engine is closed down. The pump is the more economical; but
when the engine is not working the exhaust steam is not sufficient to
heat the water in the heater; and pumping cold water into the boiler
will quickly bring down the pressure and injure the boiler.


ECONOMICAL FIRING.

The management of the fire is one of the most important things in
running a steam engine. On it depend two things of the greatest
consequence--success in getting up steam quickly and keeping it at
a steady pressure under all conditions; and economy in the use of
fuel. An engineer who understands firing in the most economical way
will probably save his wages to his employer over the engineer who is
indifferent or unscientific about it. Therefore the young engineer
should give the subject great attention.

First, let us consider firing with coal. All expert engineers advise
a “thin” fire. This means that you should have a thin bed of coals,
say about four inches thick, all over the grate. There should be no
holes or dead places in this, for if there are any, cold air will
short-circuit into the fire flues and cool off the boiler.

The best way of firing is to spread the coal on with a small hand
shovel, a very little at a time, scattering it well over the fire.
Another way, recommended by some, is to have a small pile of fresh fuel
at the front of the grate, pushing it back over the grate when it is
well lighted. To manage this well will require some practice and skill,
and for a beginner, we recommend scattering small shovelsful all over
the fire. All lump coal should be broken to a uniform size. No piece
larger than a man’s fist should be put in a firebox.

Seldom use the poker above the fire, for nothing has such a tendency
to put out a coal fire as stirring it with a poker above. And when
there is a good glow all over the grate below, the poker is not needed
below. When the grate becomes covered with dead ashes, they should be
cautiously but fully removed, and clinkers must be lifted out with the
poker from above, care being exercised to cover up the holes with live
coals.

Hard coal if used should be dampened before being put on the fire.

When the fire is burning a little too briskly, close the draft but do
not tamper with the fire itself. Should it become important on a sudden
emergency to check the fire at any time quickly, never dash water upon
it, but rather throw plenty of fresh fuel upon it. Fresh fuel always
lowers the heat at first. If all drafts are closed tight, it will lower
the heat considerably for quite a time.

In checking a fire, it must be remembered that very sudden cooling
will almost surely crack the boiler. If there is danger of an explosion
it may be necessary to draw the fire out entirely; but under no
circumstances should cold water be thrown on. After drawing the fire
close all doors and dampers.


FIRING WITH WOOD.

Always keep the fire door shut as much as possible, as cold air thus
admitted will check the fire and ruin the boiler.

Firing with wood is in many ways the exact reverse of firing with coal.
The firebox should be filled full of wood at all times. The wood should
be thrown in in every direction, in pieces of moderate size, and as it
burns away, fresh pieces should be put in at the front so that they
will get lighted and ready to burn before being pushed back near the
boiler. It often helps a wood fire, too, to stir it with a poker. Wood
makes much less ash than coal, and what little accumulates in the grate
will not do much harm. Sometimes green wood will not burn because it
gets too much cold air. In that case the sticks should be packed as
close together as possible, still leaving a place for the air to pass.
Also a wood fire, especially one with green wood, should be kept up to
a high temperature all the time; for if it is allowed to drop down the
wood will suddenly cease to burn at all.


FIRING WITH STRAW.

In firing with straw it is important to keep the shute full of straw
all the time so that no cold air can get in on top of the fire. Don’t
push the straw in too fast, either, but keep it moving at a uniform
rate, with small forkfulls. Now and then it is well to turn the fork
over and run it down into the fire to keep the fire level. Ashes may
be allowed to fill up in rear of ash box, but fifteen inches should be
kept clear in front to provide draft. The brick arch may be watched
from the side opening in the firebox, and should show a continuous
stream of white flame coming over it. If too much straw is forced in,
that will check the flame. The flame should never be checked. If damp
straw gets against the ends of the flues, it should be scraped off with
the poker from side door. Clean the tubes well once a day. The draft
must always be kept strong enough to produce a white heat, and if this
cannot be done otherwise, a smaller nozzle may be used on the exhaust
pipe; but this should be avoided when possible, since it causes back
pressure on the engine. Never let the front end of the boiler stand
on low ground. Engine should be level, or front end high, if it has a
firebox locomotive boiler; if a return flue boiler, be careful to keep
it always level. In burning straw take particular notice that the spark
screen in stack does not get filled up.


THE ASH PIT.

In burning coal it is exceedingly important that the ashes be kept
cleaned out, as the hot cinders falling down on the heap of ashes
almost as high as the grate will overheat the grate in a very short
time and warp it all out of shape, so ruining it.

With wood and straw, on the contrary, an accumulation of ashes will
often help and will seldom do any harm, because no very hot cinders can
drop down below the grates, and the hottest part of the fire is some
distance above the grates.


STARTING A FIRE.

You must make up your mind that it will take half an hour to an hour
or so to get up steam in any boiler that is perfectly cold. The metal
expands and shrinks a great deal with the heat and cold, and a sudden
application of heat would ruin a boiler in a short time. Hence it is
necessary for reasons of engine economy to make changes of temperature,
either cooling off or heating up, gradually.

First see that there is water in the boiler.

Start a brisk fire with pine kindlings, gradually putting on coal or
wood, as the case may be, and spreading the fire over the grate so that
all parts will be covered with glowing coals.

When you have 15 or 20 pounds of steam, start the blower. As has
already been described, the blower is a pipe with a nozzle leading from
the steam space of the boiler to the smoke stack, and fitted with a
globe valve. The force of the steam drives the air out of the stack,
causing a vacuum, which is immediately filled by the hot gases from
the firebox coming through the boiler tubes. Little is to be gained by
using the blower with less than 15 pounds of steam, as the blower has
so little strength below that, that it draws off about as much steam as
is made and nothing is gained.

The blower is seldom needed when the engine is working, as the exhaust
steam should be sufficient to keep the fire going briskly. If it is
not, you should conclude that something is the matter. There are times,
however, when the blower is required even when the engine is going.
For example, if you are working with very light load and small use of
steam, the exhaust may be insufficient to keep up the fire; and this
will be especially true if the fuel is very poor. In such a case, turn
on the blower very slightly. But remember that you are wasting steam if
you can get along without the blower.

Examine the nozzle of the blower now and then to see that it does not
become limed up, or turned so as to direct the steam to one side of the
stack, where its force would be wasted.

Beware, also, of creating too much draft; for too much draft will use
up fuel and make little steam.


SMOKE.

Coal smoke is nothing more or less than unburned carbon. The more smoke
you get, the less will be the heat from a given amount of fuel. Great
clouds of black smoke from an engine all the time are a very bad sign
in an engineer. They show that he does not know how to fire. He has not
followed the directions already given, to have a thin, hot fire, with
few ashes under his grate. Instead, he throws on great shovelsful of
coal at a time, and has the coal up to the firebox door. His fuel is
always making smoke, which soon clogs up the smoke flues and lessens
the amount of steam he is getting. If he had kept his fire very
“thin,” but very hot, throwing on a small hand shovel of coal at a
time, seldom poking his fire except to lift out clinkers or clean away
dead ashes under the grate, and keeping his ashpit free from ashes,
there would be only a little puff of black smoke when the fresh coal
went on, and then the smoke would quickly disappear, while the fire
flues would burn clean and not get clogged up with soot.

It is important, however, to keep the small fire flues especially
well cleaned out with a good flue cleaner; for all accumulation of
soot prevents the heat from passing through the steel, and so reduces
the heating capacity of the boiler. Cleaning the tubes with a steam
blower is never advisable, as it forms a paste on the tube that greatly
impairs its commodity.


SPARKS.

With coal there is little danger of fires caused by sparks from the
engine. What sparks there are are heavy and dead, and will even fall
on a pile of straw without setting it on fire. On a very windy day,
however, when you are running your engine very hard, especially if it
is of the direct locomotive boiler type, you want to be careful even
with coal.

With wood it is very different; and likewise with straw. Wood and straw
sparks are always dangerous, and an engine should never be run for
threshing with wood or straw without using a spark-arrester.

It sometimes happens that when coal is used it will give out, and you
will be asked to finish your job with wood. In such a case, it is the
duty of an engineer to state fully and frankly the danger of firing
with wood without a spark arrester, and he should go on only when
ordered to do so by the proprietor, after he has been fully warned. In
that case all responsibility is shifted from the engineer to the owner.


THE FUSIBLE PLUG.

The careful engineer will never have occasion to do anything to the
fusible plug except to clean the scale off from the top of it on the
inside of the boiler once a week, and put in a fresh plug once a month.
It is put in merely as a precaution to provide for carelessness. The
engineer who allows the fusible plug to melt out is by that very fact
marked as a careless man, and ought to find it so much the harder to
get a job.

As has already been explained, the fusible plug is a plug filled in
the middle with some metal that will melt at a comparatively low
temperature. So long as it is covered with water, no amount of heat
will melt it, since the water conducts the heat away from the metal
and never allows it to rise above a certain temperature. When the plug
is no longer covered with water, however,--in short, when the water
has fallen below the danger line in the boiler--the metal in the plug
will fuse, or melt, and make an opening through which the steam will
blow into the firebox and put out the fire. However, if the top of the
fusible plug has been allowed to become thickly coated with scale, this
safety precaution may not work and the boiler may explode. In any case
the fusible plug is not to be depended on.

At the same time a good engineer will take every precaution, and one of
these is to keep the top of the plug well cleaned. Also he will have
an extra plug all ready and filled with composition metal, to put in
should the plug in the boiler melt out. Then he will refill the old
plug as soon as possible. This may be done by putting a little moist
clay in one end to prevent the hot metal from running through, and then
pouring into the other end of the plug as much melted metal as it will
hold. When cold, tamp down solidly.


LEAKY FLUES.

One common cause of leaky flues is leaving the fire door open so that
currents of cold air will rush in on the heated flues and cause them,
or some other parts of the boiler, to contract too suddenly. The
best boiler made may be ruined in time by allowing cold currents of
air to strike the heated interior. Once or twice will not do it; but
continually leaving the fire door open will certainly work mischief in
the end.

Of course, if flues in a new boiler leak, it is the fault of the boiler
maker. The tubes were not large enough to fill the holes in the tube
sheets properly. But if a boiler runs for a season or so and then the
flues begin to leak, the chances are that it is due to the carelessness
of the engineer. It may be he has been making his fires too hot; it may
be leaving the firebox door open; it may be running the boiler at too
high pressure; it may be blowing out the boiler when it is too hot; or
blowing out the boiler when there is still some fire in the firebox; it
may be due to lime encrusted on the inside of the tube sheets, causing
them to overheat. Flues may also be made to leak by pumping cold water
into the boiler when the water inside is too low; or pouring cold water
into a hot boiler will do it. Some engineers blow out their boilers to
clean them, and then being in a hurry to get to work, refill them while
the metal is hot. The flues cannot stand this, since they are thinner
than the shell of the boiler and cool much more quickly; hence they
will contract much faster than the rest of the boiler and something has
to come loose.

Once a flue starts to leaking, it is not likely to stop till it has
been repaired; and one leaky flue will make others leak.

Now what shall you do with a leaky flue?

To repair a leaky flue you should have a flue expander and a calking
tool, with a light hammer. If you are small enough you will creep in
at the firebox door with a candle in your hand. First, clean off the
ends of the flues and flue sheet with some cotton waste. Then force the
expander into the leaky flue, bringing the shoulder well up against
the end of the flue. Then drive in the tapering pin. Be very careful
not to drive it in too far, for if you expand the flue too much, you
will strain the flue sheet and cause other flues to leak. You must use
your judgment and proceed cautiously. It is better to make two or three
trials than to spoil your boiler by bad work. The roller expander is
preferable to the Prosser in the hands of a novice. The tube should be
expanded only enough to stop the leak. Farther expanding will only do
injury.

When you think the flue has been expanded enough, hit the pin a side
blow to loosen it. Then turn the expander a quarter round, and drive in
the pin again. Loosen up and continue till you have turned the expander
entirely around.

Finally remove the expander, and use the calking tool to bead the end.
It is best, however, to expand all leaky flues before doing any beading.

The beading is done by placing the guide or gauge inside the flue,
and then pounding the ends of the flue down against the flue sheet by
light blows. Be very careful not to bruise the flue sheet or flues, and
use no heavy blows, nor even a heavy hammer. Go slowly and carefully
around the end of each flue; and if you have done your work thoroughly
and carefully the flues will be all right. But you should test your
boiler before steaming up, to make sure that all the leaks are stopped,
especially if there have been bad ones.

There are various ways to testing a boiler. If waterworks are handy,
connect the boiler with a hydrant and after filling the boiler, let it
receive the hydrant pressure. Then examine the calked flues carefully,
and if you see any seeping of water, use your beader lightly till the
water stops. In case no waterworks with good pressure are at hand, you
can use a hydraulic pump or a good force pump.

The amount of pressure required in testing a boiler should be that at
which the safety valve is set to blow off, say 110 to 130 lbs. This
will be sufficient.

If you are in the field with no hydrant or force pump handy, you may
test your boiler in this way: Take off the safety valve and fill the
boiler full of water through the safety valve opening. Then screw the
safety back in its place. You should be sure that every bit of space in
the boiler is filled entirely full of water, with all openings tightly
closed. Then get back in the boiler and have a bundle of straw burned
under the firebox, or under the waist of the boiler, so that at some
point the water will be slightly heated. This will cause pressure. If
your safety valve is in perfect order, you will know as soon as water
begins to escape at the safety valve whether your flues are calked
tight enough or not.

The water is heated only a few degrees, and the pressure is cold water
pressure. In very cold weather this method cannot be used, however, as
water has no expansive force within five degrees of freezing.

The above methods are not intended for testing the safety of a boiler,
but only for testing for leaky flues. If you wish to have your boiler
tested, it is better to get an expert to do it.




CHAPTER V.

HOW TO MANAGE A TRACTION ENGINE.


A traction engine is usually the simplest kind of an engine made. If
it were not, it would require a highly expert engineer to run it,
and this would be too costly for a farmer or thresherman contractor.
Therefore the builders of traction engines make them of the fewest
possible parts, and in the most durable and simple style. Still, even
the simplest engine requires a certain amount of brains to manage it
properly, especially if you are to get the maximum of work out of it at
the lowest cost.

If the engine is in perfect order, about all you have to do is to see
that all bearings are properly lubricated, and that the automatic oiler
is in good working condition. But as soon as an engine has been used
for a certain time, there will be wear, which will appear first in the
journals, boxes and valve, and it is the first duty of a good engineer
to adjust these. To adjust them accurately requires skill; and it is
the possession of that skill that goes to make a real engineer.

Your first attention will probably be required for the cross-head and
crank boxes or brasses. The crank box and pin will probably wear first;
but both the cross-head and crank boxes are so nearly alike that what
is said of one will apply to the other.

You will find the wrist box in two parts. In a new engine these parts
do not quite meet. There is perhaps an eighth of an inch waste space
between them. They are brought up to the box in most farm engines by a
wedge-shaped key. This should be driven down a little at a time as the
boxes wear, so as to keep them snug up to the pin, though not too tight.

You continue to drive in the key and tighten up the boxes as they wear
until the two halves come tight together. Then you can no longer
accomplish anything in this way.

When the brasses have worn so that they can be forced no closer
together, they must be taken off and the ends of them filed where they
come together. File off a sixteenth of an inch from each end. Do it
with care, and be sure you get the ends perfectly even. When you have
done this you will have another eighth of an inch to allow for wear.

Now, by reflection you will see that as the wrist box wears, and the
wedge-shaped key is driven in, the pitman (or piston arm) is lengthened
to the amount that the half of the box farthest from the piston has
worn away. When the brasses meet, this will amount to one-sixteenth of
an inch.

Now if you file the ends off and the boxes wear so as to come together
once more, the pitman will have been shortened one-eighth of an inch;
and pretty soon the clearance of the piston in the cylinder will
have been offset, and the engine will begin to pound. In any case,
the clearance at one end of the cylinder will be one-sixteenth or
one-eighth of an inch less, and in the other end one-sixteenth or
one-eighth of an inch more. When this is the case you will find that
the engine is not working well.

To correct this, when you file the brasses either of the cross-head
box or the crank box you must put in some filling back of the brass
farthest from the piston, sufficient to equalize the wear that has
taken place, that is, one-sixteenth of an inch each time you have
to file off a sixteenth of an inch. This filling may be some flat
pieces of tin or sheet copper, commonly called shims, and the process
is called shimming. As to the front half of the box, no shims are
required, since the tapering key brings that box up to its proper place.

Great care must be exercised when driving in the tapering key or wedge
to tighten up the boxes, not to drive it in too hard. Many engineers
think this is a sure remedy for “knocking” in an engine, and every time
they hear a knock they drive in the crank box key. Often the knock is
from some other source, such as from a loose fly wheel, or the like.
Your ear is likely to deceive you; for a knock from any part of an
engine is likely to sound as if it came from the crank box. If you
insist on driving in the key too hard and too often, you will ruin your
engine.

In tightening up a key, first loosen the set screw that holds the key;
then drive down the key till you think it is tight; then drive it back
again, and this time force it down with your fist as far as you can. By
using your fist in this way after you have once driven the pin in tight
and loosened it again you may be pretty certain you are not going to
get it so tight it will cause the box to heat.


WHAT CAUSES AN ENGINE TO KNOCK.

The most common sign that something is loose about an engine is
“knocking,” as it is called. If any box wears a little loose, or any
wheel or the like gets a trifle loose, the engine will begin to knock.

When an engine begins to knock or run hard, it is the duty of the
engineer to locate the knock definitely. He must not guess at it. When
he has studied the problem out carefully, and knows where the knock is,
then he may proceed to remedy it. Never adjust more than one part at a
time.

As we have said, a knock is usually due to looseness somewhere. The
journals of the main shaft may be loose and cause knocking. They are
held in place by set bolts and jam nuts, and are tightened by simply
screwing up the nuts. But a small turn of a nut may make the box so
tight it will begin to heat at once. Great care should be taken in
tightening up such a box to be sure not to get it too tight. Once a box
begins to cut, it should be taken out and thoroughly cleaned.

Knocking may be due to a loose eccentric yoke. There is packing between
the two halves of the yoke, and to tighten up you must take out a thin
layer of this packing. But be careful not to take out too much, or the
eccentric will stick and begin to slip.

Another cause of knocking is the piston rod loose in the cross-head.
If the piston rod is keyed to the cross-head it is less liable to get
loose than if it were fastened by a nut; but if the key continues to
get loose, it will be best to replace it with a new one.

Unless the piston rod is kept tight in the cross-head, there is
liability of a bad crack. A small strain will bring the piston out of
the cross-head entirely, when the chances are you will knock out one or
both cylinder-heads. If a nut is used, there will be the same danger if
it comes off. It should therefore be carefully watched. The best way is
to train the ear to catch any usual sound, when loosening of the key or
nut will be detected at once.

Another source of knocking is looseness of the cross-head in the
guides. Provision is usually made for taking up the wear; but if there
is not, you can take off the guides and file them or have them planed
off. You should take care to see that they are kept even, so that they
will wear smooth with the crosshead shoes.

If the fly-wheel is in the least loose it will also cause knocking,
and it will puzzle you not a little to locate it. It may appear to be
tight; but if the key is the least bit too narrow for the groove in the
shaft, it will cause an engine to bump horribly, very much as too much
“lead” will.


LEAD.

We have already explained what “lead” is. It is opening of the port at
either end of the steam cylinder allowed by the valve when the engine
is on a dead centre. To find out what the lead is, the cover of the
steam chest must be taken off, and the engine placed at each dead
centre in succession. If the lead is greater at one end than it is at
the other, the valve must be adjusted to equalize it. As a rule the
engine is adjusted with a suitable amount of lead if it is equalized.
The correct amount of lead varies with the engine and with the port
opening. If the port opening is long and narrow, the lead should
obviously be less than if the port is short and wide.

If the lead is insufficient, there will not be enough steam let into
the cylinder for cushion, and the engine will knock. If there is too
much lead the speed of the engine will be lessened, and it will not do
the work it ought. To adjust the lead _de novo_ is by no means an easy
task.


HOW TO SET A SIMPLE VALVE.

In order to set a valve the engine must be brought to a dead centre.
This cannot be done accurately by the eye. An old engineer[5] gives
the following directions for finding the dead centre accurately. Says
he: “First provide yourself with a ‘tram.’ This is a rod of one-fourth
inch iron about eighteen inches long, with two inches at one end bent
over to a sharp angle. Sharpen both ends to a point. Fasten a block of
hard wood somewhere near the face of the fly-wheel, so that when the
straight end of your tram is placed at a definite point in the block,
the hooked end will reach the crown of the fly-wheel. The block must be
held firmly in its place, and the tram must always touch it at exactly
the same point.

  Footnote 5: J. H. Maggard.

“You are now ready to set about finding the dead centre. In doing this,
remember to turn the fly-wheel always in the same direction.

“Bring the engine over till it nearly reaches one of the dead centres,
but not quite. Make a distinct mark across the cross-head and guides.
Also go around to the flywheel, and placing the straight end of the
tram at the selected point on the block of wood, make a mark across the
crown or centre of face of the fly-wheel. Now turn your engine past the
centre, and on to a point at which the mark on the cross head will once
more exactly correspond with the line on the guides, making a single
straight line. Once more place the tram as before and make another mark
across the crown of the fly-wheel. By use of dividers, find the exact
centre between the two marks made on the fly-wheel, and mark this point
distinctly with a centre punch. Now bring the fly-wheel to the point
where the tram, set with its straight end at the required point on the
block of wood, will touch this point with the hooked end, and you will
have one of the dead centres.

“Turn the engine over and proceed in the same way to find the other
dead centre.”

Now, setting the engine on one of the dead centres, remove the cover of
the steam chest and proceed to set your valve.

Assuming that the engine maker gave the valve the proper amount of lead
in the first place, you can proceed on the theory that it is merely
necessary to equalize the lead at both ends. Assume some convenient
lead, as one-sixteenth of an inch, and set the valve to that. Then
turn the engine over and see if the lead at the other end is the same.
If it is the same, you have set the valve correctly. If it is less at
the other end, you may conclude that the lead at both ends should be
less than one-sixteenth of an inch, and must proceed to equalize it.
This you can do by fitting into the open space a little wedge of wood,
changing the valve a little until the wedge goes in to just the same
distance at each end. Then you may know that the lead at one end is the
same as at the other end. You can mark the wedge for forcing it against
the metal, or mark it against the seat of the valve with a pencil.

The valve is set by loosening the set screws that hold the eccentric on
the shaft. When these are loosened up the valve may be moved freely.
When it is correctly set the screws should be tightened, and the
relative position of the eccentric on the shaft may be permanently
marked by setting a cold chisel so that it will cut into the shaft
and the eccentric at the same time and giving it a smart blow with
the hammer, so as to make a mark on both the eccentric and the shaft.
Should your eccentric slip at any time in the future, you can set your
valve by simply bringing the mark on the eccentric so that it will
correspond with the mark on the shaft. Many engines have such a mark
made when built, to facilitate setting a valve should the eccentric
become loose.

These directions apply only to setting the valve of a single eccentric
engine.


HOW TO SET A VALVE ON A DOUBLE ECCENTRIC ENGINE.

In setting a valve on a reversible or double eccentric engine, the link
may cause confusion, and you may be trying to set the valve to run one
way when the engine is set to run the other.

The valve on such an engine is exactly the same as on a single
eccentric engine. Set the reverse lever for the engine to go forward.
Then set the valve exactly as with a single eccentric engine. When
you have done so, tighten the eccentric screws so that they will hold
temporarily, and set the reverse lever for the engine to go backward.
Then put the engine on dead centres and see if the valve is all right
at both ends. If it is, you may assume that it is correctly set, and
tighten eccentric screws, marking both eccentrics as before.

As we have said, most engines are marked in the factory, so that it is
not a difficult matter to set the valves, it being necessary only to
bring the eccentric around so that the mark on it will correspond with
the mark on the shaft.

You can easily tell whether the lead is the same at both ends by
listening to the exhaust. If it is longer at one end than the other,
the valve is not properly set.


SLIPPING OF THE ECCENTRIC OR VALVE.

If the eccentric slips the least bit it may cause the engine to stop,
or to act very queerly. Therefore the marks on the shaft and on the
eccentric should be watched closely, and of course all grease and dirt
should be kept wiped off, so that they can be seen easily. Then the jam
nuts should be tightened up a little from time to time.

If the engine seems to act strangely, and yet the eccentrics are all
right, look at the valve in the steam chest. If the valve stem has
worked loose from the valve, trouble will be caused. It may be held in
place by a nut, and the nut may work off; or the valve may be held by
a clamp and pin, and the pin may work loose. Either will cause loss of
motion, and perhaps a sudden stopping of the engine.


USE OF THE CYLINDER STEAM COCKS.

It is a comparatively simple matter to test a steam cylinder by use
of the cylinder cocks. To do this, open both cocks, place the engine
on the forward center, and turn on a little steam. If the steam blows
out at the forward cock, we may judge that our lead is all right. Now
turn the engine to the back center and let on the steam. It should blow
out the same at the back cock. A little training of the ear will show
whether the escape of steam is the same at both ends. Then reverse the
engine, set it on each center successfully, and notice whether the
steam blows out from one cock at a time and in the same degree of force.

If the steam blows out of both cocks at the same time, or out of one
cock on one center, but not out of the other cock on its corresponding
center, we may know something is wrong. The valve does not work
properly.

We will first look at the eccentrics and see that they are all right.
If they are, we must open the steam chest, first turning off all steam.
Probably we shall find that the valve is loose on the valve rod, if our
trouble was that the steam blew out of the cock but did not out of the
other when the engine was on the opposite center.

If our trouble was that steam blew out of both cocks at the same time,
we may conclude either that the cylinder rings leak or else the valve
has cut its seat. It will be a little difficult to tell which at first
sight. In any case it is a bad thing, for it means loss of power and
waste of steam and fuel. To tell just where the trouble is you must
take off the cylinder head, after setting the engine on the forward
center. Let in a little steam from the throttle. If it blows through
around the rings, the trouble is with them; but if it blows through the
valve port, the trouble is with the valve and valve seat.

If the rings leak you must get a new set if they are of the
self-adjusting type. But if they are of the spring or adjusting type
you can set them out yourself; but few engines now use the latter kind
of rings, so a new pair will probably be required.

If the trouble is in the valve and valve seat, you should take the
valve out and have the seat planed down, and the valve fitted to the
seat. This should always be done by a skilled mechanic fully equipped
for such work, as a novice is almost sure to make bad work of it. The
valve seat and valve must be scraped down by the use of a flat piece
of very hard steel, an eighth of an inch thick and about 3 by 4 inches
in size. The scraping edge must be absolutely straight. It will be a
slow and tedious process, and a little too much scraping on one side or
the other will prevent a perfect fit. Both valve and valve seat must
be scraped equally. Novices sometimes try to reseat a valve by the use
of emery. This is very dangerous and is sure to ruin the valve, as it
works into the pores of the iron and causes cutting.


LUBRICATION.

A knowledge of the difference between good oil and poor oil, and of how
to use oil and grease, is a prime essential for an engineer.

First let us give a little attention to the theory of lubrication. The
oil or grease should form a lining between the journal and its pin or
shaft. It is in the nature of a slight and frictionless cushion at all
points where the two pieces of metal meet.

Now if oil is to keep its place between the bearing and the shaft or
pin it must stick tight to both pieces of metal, and the tighter the
better. If the oil is light the forces at work on the bearings will
force the oil away and bring the metals together. As soon as they come
together they begin to wear on each other, and sometimes the wear is
very rapid. This is called “cutting.” If a little sand or grit gets
into the bearing, that will help the cutting wonderfully, and more
especially if there is no grease there.

For instance, gasoline and kerosene are oils, but they are so light
they will not stick to a journal, and so are valueless for lubricating.
Good lubricating oil will cost a little more than cheap oil which has
been mixed with worthless oils to increase its bulk without increasing
its cost. The higher priced oil will really cost less in the end,
because there is a larger percentage of it which will do service. A
good engineer will have it in his contract that he is to be furnished
with good oil.

Now an engine requires two different kinds of oil, one for the
bearings, such as the crank, pin, the cross-head and journals, and
quite a different kind for lubricating the steam cylinder.

It is extremely important that the steam cylinder should be well
lubricated; and this cannot be done direct. The oil must be carried
into the valve and cylinder with steam. The heat of the steam,
moreover, ranging from about 320 degrees Fahr. for 90 lbs. pressure to
350 degrees for 125 lbs. of pressure, will quickly destroy the efficacy
of a poor oil, and a good cylinder oil must be one that will stick to
the cylinder and valve seat under this high temperature. It must have
staying qualities.

The link reverse is one of the best for its purpose; but it requires a
good quality of oil on the valve for it to work well. If the valve gets
a little dry, or the poor oil used does not serve its purpose properly,
the link will begin to jump and pound. This is a reason why makers are
substituting other kinds of reverse gear in many ways not as good, but
not open to this objection. If a link reverse begins to pound when you
are using good oil, and the oiler is working properly, you may be sure
something is the matter with the valve or the gear.

A good engineer will train his ear so that he will detect by simply
listening at the cylinder whether everything is working exactly as it
ought. For example, the exhaust at each end of the cylinder, which you
can hear distinctly, should be the same and equal. If the exhaust at
one end is less than it is at the other, you may know that one end of
the cylinder is doing more work than the other. And also any little
looseness or lack of oil will signify itself by the peculiar sound it
will cause.

While the cylinder requires cylinder oil, the crank, cross-head and
journals require engine oil, or hard grease. The use of hard grease is
rapidly increasing, and it is highly to be recommended. With a good
automatic spring grease cup hard grease will be far less likely to let
the bearings heat than common oil will. At the same time it will be
much easier to keep an engine clean if hard grease is used.

An old engineer[6] gives the following directions for fitting a grease
cup on a box not previously arranged for one: “Remove the journal,
take a gouge and cut a clean groove across the box, starting at one
corner, about one-eighth of an inch from the point of the box, and
cut diagonally across, coming out at the opposite corner on the other
end of the box. Then start at the opposite corner and run through as
before, crossing the first groove in the center of the box. Groove both
halves of the box the same, being careful not to cut out at either
end, as this will allow the grease to escape from the box and cause
unnecessary waste. The shimming or packing in the box should be cut so
as to touch the journal at both ends of the box, but not in the center
or between these two points. So when the top box is brought down tight
this will form another reservoir for the grease. If the box is not
tapped directly in the center for the cup, it will be necessary to cut
another groove from where it is tapped into the grooves already made.
A box prepared in this way and carefully polished inside, will require
little attention if you use good grease.”

  Footnote 6: J. H. Maggard.


A HOT BOX.

When a box heats in the least degree, it is a sign that for lack of oil
or for some other reason the metals are wearing together.

The first thing to do, of course, is to see that the box is supplied
with plenty of good oil or grease.

If this does not cause the box to cool off, take it apart and clean it
thoroughly. Then coat the journal with white lead mixed with good oil.
Great care should be exercised to keep all dirt or grit out of your can
of lead and away from the bearing.

Replace the oil or grease cup, and the box will soon cool down.


THE FRICTION CLUTCH.

Nearly all traction engines are now provided with the friction clutch
for engaging the engine with the propelling gear. The clutch is usually
provided with wooden shoes, which are adjustable as they wear; and the
clutch is thrown on by a lever, conveniently placed.

[Illustration: A. W. STEVENS CO. FRICTION CLUTCH.]

Before running an engine, you must make sure that the clutch shoes are
properly adjusted. Great care must be taken to be sure that both shoes
will come in contact with the friction wheel at the same instant; for
if one shoe touches the wheel before the other the clutch will probably
slip.

The shoes should be so set as to make it a trifle difficult to draw the
lever clear back.

To regulate the shoes on the Rumely engine, for example, first throw
the friction in. The nut on the top of the toggle connecting the sleeve
of the friction with the shoe must then be loosened, and the nut below
the shoe tightened up, forcing the shoe toward the wheel. Both shoes
should be carefully adjusted so that they will engage the band wheel
equally and at exactly the same time.

To use the friction clutch, first start the engine, throwing the
throttle gradually wide open. When the engine is running at its usual
speed, slowly bring up the clutch until the gearing is fully engaged,
letting the engine start slowly and smoothly, without any jar.

Traction engines having the friction clutch are also provided with a
pin for securing a rigid connection, to be used in cases of necessity,
as when the clutch gets broken or something about it gives out, or you
have difficulty in making it hold when climbing hills. This pin is a
simple round or square pin that can be placed through a hole in one of
the spokes of the band wheel until it comes into a similar opening in
the friction wheel. When the pin is taken out, so as to disconnect the
wheels, it must be entirely removed, not left sticking in the hole, as
it is liable to catch in some other part of the machinery.

[Illustration: AULTMAN & TAYLOR FRICTION CLUTCH.]


MISCELLANEOUS SUGGESTIONS.

Be careful not to open the throttle valve too quickly, or you may throw
off the driving belt. You may also stir up the water and cause it to
pass over with the steam, starting what is called “priming.”

Always open your cylinder cocks when you stop, to make sure all water
has been drained out of the cylinder; and see that they are open when
you start, of course closing them as soon as the steam is let in.

When you pull out the ashes always have a pail of water ready, for you
may start a fire that will do no end of damage.

If the water in your boiler gets low and you are waiting for the tank
to come up, don’t think you “can keep on a little longer,” but stop
your engine at once. It is better to lose a little time than run the
risk of an explosion that will ruin your reputation as an engineer and
cause your employer a heavy expense.

Never start the pump when the water in the boiler is low.

Be sure the exhaust nozzle does not get limed up, and be sure the pipe
where the water enters the boiler from the heater is not limed up, or
you may split a heater pipe or knock out a check valve.

Never leave your engine in cold weather without draining off all the
water; and always cover up your engine when you leave it.

Never disconnect the engine with a leaky throttle.

Keep the steam pressure steady, not varying more than 10 to 15 lbs.

If called on to run an old boiler, have it thoroughly tested before you
touch it.

Always close your damper before pulling through a stack yard.

Examine every bridge before you pull on to it.

Do not stop going down a steep grade.




CHAPTER VI.

HANDLING A TRACTION ENGINE ON THE ROAD.


It is something of a trick to handle a traction engine on the road. The
novice is almost certain to run it into a ditch the first thing, or get
stuck on a hill, or in a sand patch or a mudhole. Some attention must
therefore be paid to handling a traction engine on the road.

In the first place, never pull the throttle open with a jerk, nor put
down the reverse lever with a snap. Handle your engine deliberately
and thoughtfully, knowing beforehand just what you wish to do and how
you will do it. A traction engine is much like an ox; try to goad it
on too fast and it will stop and turn around on you. It does its best
work when moving slowly and steadily, and seldom is anything gained by
rushing.

The first thing for an engineer to learn is to handle his throttle.
When an engine is doing work the throttle should be wide open; but on
the road, or in turning, backing, etc., the engineer’s hand must be
on the throttle all the time and he must exercise a nice judgment as
to just how much steam the engine will need to do a certain amount
of work. This the novice will find out best by opening the throttle
slowly, taking all the time he needs, and never allowing any one to
hurry him.

As an engineer learns the throttle, he gradually comes to have
confidence in it. As it were, he feels the pulse of the animal and
never makes a mistake. Such an engineer always has power to spare, and
never wastes any power. He finds that a little is often much better
than too much.

The next thing to learn is the steering wheel. It has tricks of its
own, which one must learn by practice. Most young engineers turn the
wheel altogether too much. If you let your engine run slowly you will
have time to turn the wheel slowly, and accomplish just what you want
to do. If you hurry you will probably have to do your work all over
again, and so lose much more time in the end than if you didn’t hurry.

Always keep your eyes on the front wheels of the engine, and do not
turn around to see how your load is coming on. Your load will take care
of itself if you manage the front wheels all right, for they determine
where you are to go.

In making a hard turn, especially, go slow. Then you will run no chance
of losing control of your engine, and you can see that neither you nor
your load gets into a ditch.


GETTING INTO A HOLE.

You are sure sooner or later to get into a hole in the road, for a
traction engine is so heavy it is sure to find any soft spot in the
road there may be.

As to getting out of a hole, observe in the first place that you must
use your best judgment.

First, never let the drive wheels turn round without doing any work.
The more they spin round without helping you, the worse it will be for
you.

Your first thought must be to give the drive wheels something they can
climb on, something they can stick to. A heavy chain is perhaps the
very best thing you can put under them. But usually on the road you
have no chain handy. In that case, you must do what you can. Old hay or
straw will help you; and so will old rails or any old timber.

Spend your time trying to give your wheels something to hold to, rather
than trying to pull out. When the wheels are all right, the engine will
go on its way without any trouble whatever. And do not half do your
work of fixing the wheels before you try to start. See that both wheels
are secure before you put on a pound of steam. Make sure of this the
first time you try, and you will save time in the end. If you fix one
wheel and don’t fix the other, you will probably spoil the first wheel
by starting before the other is ready.

Should you be where your engine will not turn, then you are stuck
indeed. You must lighten your load or dig a way out.


BAD BRIDGES.

A traction engine is so heavy that the greatest care must be exercised
in crossing bridges. If a bridge floor is worn, if you see rotten
planks in it, or liability of holes, don’t pull on to that bridge
without taking precautions.

The best precaution is to carry with you a couple of planks sixteen
feet long, three inches thick in the middle, tapering to two inches at
the ends; also a couple of planks eight feet long and two inches thick,
the latter for culverts and to help out on long bridges.

Before pulling on to a bad looking bridge, lay down your planks, one
for each pair of wheels of the engine to run on. Be exceedingly careful
not to let the engine drop off the edge of these planks on the way
over, or pass over the ends on to the floor of the bridge. If one pair
of planks is too short, use your second pair.

Another precaution which it is wise to take is to carry fifty feet of
good, stout hemp rope, and when you come to a shaky bridge, attach your
separator to the engine by this rope at full length, so that the engine
will have crossed the bridge before the weight of the separator comes
upon it.

Cross a bad bridge very slowly. Nothing will be gained by hurrying.
There should especially be no sudden jerks or starts.


SAND PATCHES.

A sandy road is an exceedingly hard road to pull a load over.

In the first place, don’t hurry over sand. If you do you are liable to
break the footing of the wheels, and then you are gone.

In the second place, keep your engine as steady and straight as
possible, so that both wheels will always have an equal and even
bearing. They are less liable to slip if you do. It is useless to try
to “wiggle” over a sand patch. Slow, steady, and even is the rule.

If your wheels slip in sand, a bundle of straw or hay, especially old
hay, will be about the best thing to give them a footing.


HILLS.

In climbing hills take the same advice we have given you all along: Go
slow. Nothing is gained by rushing at a hill with a steam engine. Such
an engine works best when its force is applied steadily and evenly, a
little at a time.

If you have a friction clutch, as you probably will have, you should be
sure it is in good working order before you attempt to climb hills. It
should be adjusted to a nicety, as we have already explained. When you
come to a bad hill it would probably be well to put in the tight gear
pin; or use it altogether in a hilly country.

When the friction clutch first came into use, salesmen and others used
to make the following recommendation (a recommendation which we will
say right here is bad). They said, when you come to an obstacle in the
road that you can’t very well get your engine over, throw off your
friction clutch from the road wheels, let your engine get under good
headway running free, and then suddenly put on the friction clutch and
jerk yourself over the obstacle.

Now this is no doubt one way to get over an obstacle; but no good
engineer would take his chances of spoiling his engine by doing any
such thing with it. Some part of it would be badly strained by such a
procedure; and if this were done regularly all through a season, an
engine would be worth very little at the end of the season.




CHAPTER VII.

POINTS FOR THE YOUNG ENGINEER.


QUESTIONS AND ANSWERS.

THE BOILER.

Q. How should water be fed to a boiler?

A. In a steady stream, by use of a pump or injector working
continuously and supplying just the amount of water required. By this
means the water in the boiler is maintained at a uniform level, and
produces steam most evenly and perfectly.

Q. Why should pure water be used in a boiler?

A. Because impure water, or hard water, forms scales on the boiler
flues and plates, and these scales act as non-conductors of heat. Thus
the heat of the furnace is not able to pass easily through the boiler
flues and plates to the water, and your boiler becomes what is called
“a hard steamer.”

Q. What must be done to prevent the formation of scale?

A. First, use some compound that will either prevent scale from
forming, or will precipitate the scale forming substance as a soft
powder that can easily be washed off. Sal soda dissolved in the feed
water is recommended, but great care should be exercised in the use of
sal soda not to use too much at a time, as it may cause a boiler to
foam. Besides using a compound, clean your boiler often and regularly
with a hand hose and a force pump, and soak it out as often as possible
by using rain water for a day or two, especially before cleaning. Rain
water will soften and bring down the hard scale far better than any
compound.

Q. How often should you clean your boiler?

A. As often as it needs it, which will depend upon the work you do and
the condition of the water. Once a week is usually often enough if the
boiler is blown down a little every day. If your water is fairly good,
once a month will be often enough. A boiler should be blown off about
one gauge at a time two or three times a day with the blow-off if the
water is muddy.

Q. How long should the surface blow-off be left open?

A. Only for a few seconds, and seldom longer than a minute. The surface
blow-off carries off the scum that forms on the water, and other
impurities that rise with the scum.

Q. How do you clean a boiler by blowing off?

A. When the pressure has been allowed to run down open the blow-off
valve at the bottom of the boiler and let the water blow out less than
a minute, till the water drops out of sight in the water gauges, or
about two and one-half inches. Blowing off more is only a waste of heat
and fuel.

Q. What harm will be done by blowing off a boiler under a high pressure
of steam?

A. The heat in the boiler while there is such a pressure will be so
great that it will bake the scale on the inside of the boiler, and it
will be very difficult to remove it afterward. After a boiler has been
blown off the scale should be for the most part soft, so that it can be
washed out by a hose and force pump.

Q. Why should a hot boiler never be filled with cold water?

A. Because the cold water will cause the boiler to contract more in
some places than in others, and so suddenly that the whole will be
badly strained. Leaky flues are made in this way, and the life of a
boiler greatly shortened. As a rule a boiler should be filled only when
the metal and the water put into it are about at the same temperature.

Q. After a boiler has been cleaned, how should the manhole and manhole
plates be replaced?

A. They are held in position by a bolt passing through a yoke that
straddles the hole; but to be steam and water tight they must have
packing all around the junction of the plate with the boiler. The best
packing is sheet rubber cut in the form of a ring just the right size
for the bearing surface. Hemp or cotton packing are also used, but they
should be free from all lumps and soaked in oil. Do not use any more
than is absolutely needed. Be careful, also, to see that the bearings
of the plate and boiler are clean and smooth, with all the old packing
scraped off. Candle wick saturated with red lead is next best to rubber
as packing.

Q. What are the chief duties of an engineer in care of a boiler?

A. First, to watch all gauges, fittings, and working parts, to see that
they are in order; try the gauge cocks to make sure the water is at
the right height; try the safety valve from time to time to be sure it
is working; see that there are no leaks, that there is no rusting or
wearing of parts, or to replace parts when they do begin to show wear;
to examine the check valve frequently to make sure no water can escape
through it from the boiler; take precautions against scale and stoppage
of pipes by scale; and keep the fire going uniformly, cleanly, and in
an economical fashion.

Q. What should you do if the glass water gauge breaks?

A. Turn off the gauge cocks above and below, the lower one first so
that the hot water will not burn you. You may put in a new glass and
turn on gauge cocks at once. Turn on the lower or water cock first,
then the upper or steam cock. You may go on without the glass gauge,
however, using the gauge cocks or try cocks every few minutes to make
sure the water is at the right height, neither too high nor too low.

Q. Why is it necessary to use the gauge cocks when the glass gauge is
all right?

A. First, because you cannot otherwise be sure that the glass gauge is
all right; and, secondly, because if you do not use them frequently
they are likely to become scaled up so that you cannot use them in case
of accident to the glass gauge.

Q. If a gauge cock gets leaky, what should be done?

A. Nothing until the boiler has cooled down. Then if the leak is in the
seat, take it out and grind and refit it; if the leak is where the
cock is screwed into the boiler, tighten it up another turn and see if
that remedies the difficulty. If it does not you will probably have to
get a new gauge cock.

Q. Why not screw up a gauge cock while there is a pressure of steam on?

A. The cock might blow out and cause serious injury to yourself or some
one else. Make it a rule never to fool with any boiler fittings while
there is a pressure of steam on the boiler. It is exceedingly dangerous.

Sometimes a gauge cock gets broken off accidentally while the boiler is
in use. If such an accident happens, bank the fire by closing the draft
and covering the fire with fresh fuel or ashes. Stop the engine and let
the water blow out of the hole till only steam appears; then try to
plug the opening with a long whitewood or poplar, or even a pine stick
(six or eight feet long), one end of which you have whittled down to
about the size of the hole. When the steam has been stopped the stick
may be cut off close to the boiler and the plug driven in tight. If
necessary you may continue to use the boiler in this condition until a
new cock can be put in.

Q. What should you do when a gauge cock is stopped up?

A. Let the steam pressure go down, and then take off the front part
and run a small wire into the passage, working the wire back and forth
until all scale and sediment has been removed.

Q. What should you do when the steam gauge gets out of order.

A. If the steam gauge does not work correctly, or you suspect it does
not, you may test it by running the steam up until it blows off at
the safety valve. If the steam gauge does not indicate the pressure
at which the safety valve is set to pop off, and you have reason to
suppose the safety valve is all right, you may conclude that there is
something the matter with the steam gauge. In that case either put in
a new one, or, if you have no extra steam gauge on hand, shut down
your boiler and engine till you can get your steam gauge repaired.
Sometimes this can be done simply by adjusting the pointer, which may
have got loose, and you can test it by attaching it to another boiler
which has a steam gauge that is all right and by which you can check up
yours. It is VERY DANGEROUS to run your boiler without a steam gauge,
depending on the safety valve. Never allow the slightest variation in
correctness of the steam gauge without repairing it at once. It will
nearly always be cheaper in these days to put in a new gauge rather
than try to repair the old one.

Q. What should you do if the pump fails to work?

A. Use the injector.

Q. What should you do if there is no injector?

A. Stop the engine at once and bank the fire with damp ashes,
especially noting that the water does not fall below the bottom of the
glass gauge. Then examine the pump. First see if the plunger leaks air;
if it is all right, examine the check valves, using the little drain
cock as previously explained to test the upper ones, for the valves
may have become worn and will leak; third, if the check valves are all
right, examine the supply pipe, looking at the strainer, observing
whether suction takes place when the pump is worked, etc. There may
be a leak in the suction hose somewhere during its course where air
can get in, or it may become weak and collapse under the force of the
atmosphere, or the lining of the suction pipe may have become torn or
loose. The slightest leak in the suction pipe will spoil the working
of the pump. Old tubing should never be used, as it is sure to give
trouble. Finally, examine the delivery pipe. Close the cock or valve
next the boiler, and examine the boiler check valve; notice whether
the pipe is getting limed up. If necessary, disconnect the pipe and
clean it out with a stiff wire. If everything is all right up to this
point, you must let the boiler cool off, blow out the water, disconnect
the pipe between the check and the boiler, and thoroughly clean the
delivery pipe into the boiler. Stoppage of the delivery pipe is due to
deposits of lime from the heating of the water in the heater. Stoppage
from this source will be gradual, and you will find less and less
water going into your boiler from your pump until none flows at all.
From this you may guess the trouble.

Q. How may the communication with the water gauge always be kept free
from lime?

A. By blowing it off through the drain cock at the bottom. First close
the upper cock and blow off for a few seconds, the water passing
through the lower cock; then close the lower cock and open the upper
one, allowing the steam to blow through this and the drain cock for
a few seconds. If you do this every day or oftener you will have no
trouble.

Q. Should the water get low for any reason, what should be done?

A. Close all dampers tight so as to prevent all draft, and bank the
fire with fresh fuel or with ashes (damp ashes are the best if danger
is great). Then let the boiler cool down before putting in fresh water.
Banking the fire is better than drawing or dumping it, as either of
these make the heat greater for a moment or two, and that additional
heat might cause an explosion. Dashing cold water upon the fire is
also very dangerous and in every way unwise. Again, do not open the
safety valve, for that also, by relieving some of the pressure on the
superheated water, might cause it to burst suddenly into steam and so
cause an explosion.

Q. Under such circumstances, would you stop the engine?

A. No; for a sudden checking of the outflow of steam might bring about
an explosion. Do nothing but check the heat as quickly and effectively
as you can by banking or covering the fires.

Q. Why not turn on the feed water?

A. Because the crown sheet of the boiler has become overheated, and
any cold water coming upon it would cause an explosion. If the pump or
injector are running, of course you may let them run, and the boiler
will gradually refill as the heat decreases. Under such circumstances
low water is due to overheating the boiler.

Q. Would not the fusible plug avert any disaster from low water?

A. It might, and it might not. The top of it is liable to get coated
with lime so that the device is worthless. You should act at all times
precisely as if there were no fusible plug. If it ever does avert
an explosion you may be thankful, but averting explosions by taking
such means as we have suggested will be far better for an engineer’s
reputation.

Q. Would not the safety valve be a safeguard against explosion?

A. No; only under certain conditions. It prevents too high a pressure
for accumulating in the boiler when there is plenty of water; but when
the water gets low the safety valve may only hasten the explosion by
relieving some of the pressure and allowing superheated water to burst
suddenly into steam, thus vastly expanding instantly.

Q. Should water be allowed to stand in the boiler when it is not in use?

A. It is better to draw it off and clean the boiler, to prevent
rusting, formation of scale, hardening of sediment, etc., if boiler is
to be left for any great length of time.

Q. What should you do if a grate bar breaks or falls out?

A. You should always have a spare grate bar on hand to put in its
place; but if you have none you may fill the space by wedging in a
stick of hard wood cut the right shape to fill the opening. Cover
this wood with ashes before poking the fire over it, and it will last
for several hours before it burns out. You will find it exceedingly
difficult to keep up the fire with a big hole in the grate that will
let cold air into the furnace and allow coal to drop down.

In case the grate is of the rocker type the opening may be filled by
shaping a piece of flat iron, which can be set in without interfering
with the rocking of the grate; or the opening may be filled with wood
as before if the wood is covered well with ashes. Of course the use of
wood will prevent the grate from rocking and the poker must be used to
clean.

Q. Why should an engineer never start a boiler with a hot fire, and
never let his fire get hotter than is needed to keep up steam?

A. Both will cause the sheets to warp and the flues to become leaky,
because under high heat some parts of the boiler will expand more
rapidly than others. For a similar reason, any sudden application of
cold to a boiler, either cold water or cold air through the firebox
door, will cause quicker contraction of certain parts than other parts,
and this will ruin a boiler.

Q. How should you supply a boiler with water?

A. In a regular stream continually. Only by making the water pass
regularly and gradually through the heater will you get the full effect
of the heat from the exhaust steam. If a great deal of water is pumped
into the boiler at one time, the exhaust steam will not be sufficient
to heat it as it ought. Then if you have a full boiler and shut off the
water supply, the exhaust steam in the heater is wasted, for it can do
no work at all. Besides, it hurts the boiler to allow the temperature
to change, as it will inevitably do if water is supplied irregularly.

WHATEVER YOU DO, NEVER ATTEMPT TO TIGHTEN A SCREW OR CALK A BOILER
UNDER STEAM PRESSURE. IF ANYTHING IS LOOSE IT IS LIABLE TO BLOW OUT IN
YOUR FACE WITH DISASTROUS CONSEQUENCES.

Q. If boiler flues become leaky, can an ordinary person tighten them?

A. Yes, if the work is done carefully. See full explanation previously
given, p. 17. Great care should be taken not to expand the flues too
much, for by so doing you are likely to loosen other flues and cause
more leaks than you had in the first place. Small leaks inside a boiler
are not particularly dangerous, but they should be remedied at the
earliest possible moment, since they reduce the power of the boiler
and put out the fire. Besides, they look bad for the engineer.

Q. How should flues be cleaned?

A. Some use a steam blower; but a better way is to scrape off the metal
with one of the many patent scrapers, which just fill the flue, and
when attached to a rod and worked back and forth a few times the whole
length of the flue do admirable service.

Q. What harm will dirty flues do?

A. Two difficulties arise from dirty flues. If they become reduced in
size the fire will not burn well. Then, the same amount of heat will do
far less work because it is so much harder for it to get through the
layer of soot and ashes, which are non-conductors.

Q. What would you do if the throttle broke?

A. Use reverse lever.




CHAPTER VIII.

POINTS FOR THE YOUNG ENGINEER.--(CONT.)


QUESTIONS AND ANSWERS.

THE ENGINE.

Q. What is the first thing to do with a new engine?

A. With some cotton waste or a soft rag saturated with benzine or
turpentine clean off all the bright work; then clean every bearing, box
and oil hole, using a force pump with air current first, if you have
a pump, and then wiping the inside out clean with an oily rag, using
a wire if necessary to make the work thorough. If you do not clean
the working parts of the engine thus before setting it up, grit will
get into the bearings and cause them to cut. Parts that have been put
together need not be taken apart; but you should clean everything you
can get at, especially the oil holes and other places that may receive
dirt during transportation.

After the oil holes have been well cleaned, the oil cups may be wiped
off and put in place, screwing them in with a wrench.

Q. What kind of oil should you use?

A. Cylinder oil only for the cylinder; lard oil for the bearings, and
hard grease if your engine is provided with hard grease cup for the
cross-head and crank. The only good substitute for cylinder oil is pure
beef suet tried out. Merchantable tallow should never be used, as it
contains acid.

Q. Can fittings be screwed on by hand only?

A. No; all fittings should be screwed up tight with a wrench.

Q. When all fittings are in place, what must be done before the engine
can be started?

A. See that the grates in the firebox are in place and all right; then
fill the boiler with clean water until it shows an inch to an inch
and a half in the water gauge. Start your fire, and let it burn slowly
until there is a pressure in the boiler of 10 or 15 lbs. Then you can
turn on the blower to get up draft. In the meantime fill all the oil
cups with oil; put grease on the gears; open and close all cocks to
see that they work all right; turn your engine over a few times to see
that it works all right; let a little steam into the cylinder with both
cylinder cocks open--just enough to show at the cocks without moving
the engine--and slowly turn the engine over, stopping it on the dead
centers to see if the steam comes from only one of the cylinder cocks
at a time, and that the proper one; reverse the engine and make the
same test. Also see that the cylinder oiler is in place and ready for
operation. See that the pump is all right and in place, with the valve
in the feedpipe open and also the valve in the supply pipe.

By going over the engine in this way you will notice whether everything
is tight and in working order, and whether you have failed to notice
any part which you do not understand. If there is any part or fitting
you do not understand, know all about it before you go ahead.

Having started your fire with dry wood, add fuel gradually, a little
at a time, until you have a fire covering every part of the grate.
Regulate the fire by the damper alone, never opening the firebox door
even if the fire gets too hot.

Q. In what way should the engine be started?

A. When you have from 25 to 40 lbs. of pressure open the throttle valve
a little, allowing the cylinder cocks to be open also. Some steam will
condense at first in the cold cylinder, and this water must be allowed
to drain off. See that the crank is not on a dead center, and put on
just enough steam to start the engine. As soon as it gets warmed up,
and only dry steam appears at the cocks, close the cylinder cocks, open
the throttle gradually till it is wide open, and wait for the engine to
work up to its full speed.

Q. How is the speed of the engine regulated?

A. By the governor, which is operated by a belt running to the main
shaft. The governor is a delicate apparatus, and should be watched
closely. It should move up and down freely on the stem, which should
not leak steam. If it doesn’t work steadily, you should stop the engine
and adjust it, after watching it for a minute or two to see just where
the difficulty lies.

Q. Are you likely to have any hot boxes?

A. There should be none if the bearings are all clean and well supplied
with oil. However, in starting a new engine you should stop now and
then and examine every bearing by laying your hand upon it. Remember
the eccentric, the link pin, the cross-head, the crank pin. If there
is any heat, loosen the boxes up a trifle, but only a very little at
a time. If you notice any knocking or pounding, you have loosened too
much, and should tighten again.

Q. What must you do in regard to water supply?

A. After the engine is started and you know it is all right, fill the
tank on the engine and start the injector. It may take some patience
to get the injector started, and you should carefully follow the
directions previously given and those which apply especially to the
type of injector used. Especially be sure that the cocks admitting the
water through the feed pipe and into the boiler are open.

Q. Why are both a pump and an injector required on an engine?

A. The pump is most economical, because it permits the heat in the
exhaust steam to be used to heat the feed water, while the injector
heats the water by live steam. There should also be an injector,
however, for use when the engine is not working, in order that the
water in the boiler may be kept up with heated water. If a cross-head
pump is used, of course, it will not operate when the engine is not
running; and in case of an independent pump the heater will not heat
the water when the engine is not running because there is little or no
exhaust steam available. There is an independent pump (the Marsh pump)
which heats the water before it goes into the boiler, and this may be
used when the engine is shut down instead of the injector.

Q. What is the next thing to test?

A. The reversing mechanism. Throw the reverse lever back, and see if
the engine will run equally well in the opposite direction. Repeat this
a few times to make sure that the reverse is in good order.

Q. How is a traction engine set going upon the road?

A. Most traction engines now have the friction clutch. When the engine
is going at full speed, take hold of the clutch lever and slowly bring
the clutch against the band wheel. It will slip a little at first,
gradually engaging the gears and moving the outfit. Hold the clutch
lever in one hand, while with the other you operate the steering wheel.
By keeping your hand on the clutch lever you may stop forward motion
instantly if anything goes wrong. When the engine is once upon the
road, the clutch lever may set in the notch provided for it, and the
engine will go at full speed. You can then give your entire attention
to steering.

Q. What should you do if the engine has no friction clutch?

A. Stop the engine, placing the reversing lever in the center notch.
Then slide the spur pinion into the gear and open the throttle valve
wide. You are now ready to control the engine by the reversing lever.
Throw the lever forward a little, bringing it back, and so continue
until you have got the engine started gradually. When well under way
throw the reverse lever into the last notch, and give your attention to
steering.

Q. How should you steer a traction engine?

A. In all cases the same man should handle the throttle and steer the
engine. Skill in steering comes by practice, and about the only rule
that can be given is to go slow, and under no circumstances jerk your
engine about. Good steering depends a great deal on natural ability to
judge distances by the eye and power by the feel. A good engineer must
have a good eye, a good ear, and a good touch (if we may so speak). If
either is wanting, success will be uncertain.

Q. How should an engine be handled on the road?

A. There will be no special difficulty in handling an engine on a
straight, level piece of road, especially if the road is hard and
without holes. But when you come to your first hill your troubles will
begin.

Before ascending a hill, see that the water in the boiler does not
stand more than two inches in the glass gauge. If there is too much
water, as it is thrown to one end of the engine by the grade it is
liable to get into the steam cylinder. If you have too much water, blow
off a little from the bottom blow-off cock.

In descending a hill never stop your engine for a moment, since your
crown sheet will be uncovered by reason of the water being thrown
forward, and any cessation in the jolting of the engine which keeps the
water flowing over the crown sheet will cause the fusible plug to blow
out, making delay and expense.

Make it a point never to stop your engine except on the level.

Before descending a hill, shut off the steam at the throttle, and
control the engine by the friction brake; or if there is no brake, do
not quite close the throttle, but set the reverse lever in the center
notch, or back far enough to control the speed. It is seldom necessary
to use steam in going down hill, however, and if the throttle is closed
even with no friction brake, the reverse may be used in such a way as
to form an air brake in the cylinder.

Get down to the bottom of a hill as quickly as you can.

Before descending a hill it would be well to close your dampers and
keep the firebox door closed tight all the time. Cover the fire with
fresh fuel so as to keep the heat down.

The pump or injector must be kept at work, however, since as you have
let the water down low, you must not let it fall any lower or you are
likely to have trouble.

In ascending a hill, do just the reverse, namely: Keep your fire brisk
and hot, with steam pressure ascending; and throw the reverse lever in
the last notch, giving the engine all the steam you can, else you may
get stuck. If you stop you are likely to overheat forward end of fire
tubes. You are less liable to get stuck if you go slowly than if you go
fast. Regulate speed by friction clutch.




CHAPTER IX.

POINTS FOR THE YOUNG ENGINEER.--(CONT.)


MISCELLANEOUS.

Q. What is Foaming?

A. The word is used to describe the rising of water in large bubbles or
foam. You will detect it by noticing that the water in the glass gauge
rises and falls, or is foamy. It is due to sediment in the boiler, or
grease and other impurities in the feed supply. Shaking up the boiler
will start foaming sometimes; at other times it will start without
apparent cause. In such cases it is due to the steam trying to get
through a thick crust on the surface of the water.

Q. How may you prevent foaming?

A. It may be checked for a moment by turning off the throttle, so
giving the water a chance to settle. It is generally prevented by
frequently using the surface blow-off to clear away the scum. Of course
the water must be kept as pure as possible, and especially should
alkali water be avoided.

Q. What is priming?

A. Priming is not the same as foaming, though it is often caused by
foaming. Priming is the carrying of water into the steam cylinder with
the steam. It is caused by various things beside foaming, for it may
be found when the boiler is quite clean. A sudden and very hot fire
may start priming. Priming sometimes follows lowering of the steam
pressure. Often it is due to lack of capacity in the boiler, especially
lack of steam space, or lack of good circulation.

Q. How can you detect priming?

A. By the clicking sound it makes in the steam cylinder. The water in
the gauge will also go up and down violently. There will also be a
shower of water from the exhaust.

Q. What is the proper remedy for priming?

A. If it is due to lack of capacity in the boiler nothing can be done
but get a new boiler. In other cases it may be remedied by carrying
less water in the boiler when that can be done safely, by taking steam
from a different point in the steam dome, or if there is no dome by
using a long dry pipe with perforation at the end.

A larger steam pipe may help it; or it may be remedied by taking out
the top row of flues.

Leaky cylinder rings or a leaky valve may also have something to do
with it. In all cases these should be made steam tight. If the exhaust
nozzle is choked up with grease or sediment, clean it out.

A traction engine with small steam ports would prime quickly under
forced speed.

Q. How would you bank your fires?

A. Push the fire as far to the back of the firebox as possible and
cover it over with very fine coal or with dry ashes. As large a portion
as possible of the grate should be left open, so that the air may pass
over the fire. Close the damper tight. By banking your fires at night
you keep the boiler warm and can get up steam more quickly in the
morning.

Q. When water is left in the boiler with banked fire in cold weather,
what precautions ought to be taken?

A. The cocks in the glass water gauge should be closed and the drain
cock at the bottom opened, for fear the water in the exposed gauge
should freeze. Likewise all drain cocks in steam cylinder and pump
should be opened.

Q. How should a traction engine be prepared for laying up during the
winter?

A. First, the outside of the boiler and engine should be thoroughly
cleaned, seeing that all gummy oil or grease is removed. Then give the
outside of the boiler and smokestack a coat of asphalt paint, or a coat
of lampblack and linseed oil, or at any rate a doping of grease.

The outside of the boiler should be cleaned while it is hot, so that
grease, etc., may be easily removed while soft.

After the outside has been attended to, blow out the water at low
pressure and thoroughly clean the inside in the usual way, taking
out the handhole and manhole plates, and scraping off all scale and
sediment.

After the boiler has been cleaned on the inside, fill it nearly full of
water, and pour upon the top a bucket of black oil. Then let the water
out through the blow-off at the bottom. As the water goes down it will
have a coating of oil down the sides of the boiler.

All the brass fittings should be removed, including gauge cocks, check
valves, safety valve, etc. Disconnect all pipes that may contain water,
to be sure none remains in any of them. Open all stuffing boxes and
take out packing, for the packing will cause the parts they surround to
rust.

Finally, clean out the inside of the firebox and the fire flues, and
give the ash-pan a good coat of paint all over, inside as well as out.

The inside of the cylinder should be well greased, which can be done by
removing the cylinder head.

See that the top of the smoke stack is covered to keep out the weather.

All brass fittings should be carefully packed and put away in a dry
place.

A little attention to the engine when you put it up will save twice
as much time when you take it out next season, and besides save many
dollars of value in the life of the engine.

Q. How should belting be cared for?

A. First, keep belts free from dust and dirt.

Never overload belts.

Do not let oil or grease drip upon them.

Never put any sticky or pasty grease on a belt.

Never allow any animal oil or grease to touch a rubber belt, since it
will destroy the life of the rubber.

The grain or hair side should run next the pulley, as it holds better
and is not so likely to slip.

Rubber belts will be greatly improved if they are covered with a
mixture of black lead and litharge, equal parts, mixed with boiled oil,
and just enough japan to dry them quickly. This mixture will do to put
on places that peel.

Q. What is the proper way to lace a belt?

A. First, square the ends with a proper square, cutting them off to
a nicety. Begin to lace in the middle, and do not cross the laces on
the pulley side. On that side the lacings should run straight with the
length of the belt.

The holes in the belt should be punched if possible with an oval punch,
the long diameter coinciding with the length of the belt. Make two rows
of holes in each end of the belt, so that the holes in each row will
alternate with those in preceding row, making a zigzag. Four holes will
be required for a three-inch belt in each end, two holes in each row;
in a six-inch belt, place seven holes in each end, four in the row
nearest the end.

To find the length of a belt when the exact length cannot be measured
conveniently, measure a straight line from the center of one pulley
to the center of the other. Add together half the diameter of each
pulley, and multiply that by 3¼ (3.1416). The result added to twice the
distance between the centers will give the total length of the belt.

A belt will work best if it is allowed to sag just a trifle.

The seam side of a rubber belt should be placed outward, or away from
the pulley.

If such a belt slips, coat the inside with boiled linseed oil or soap.

Cotton belting may be preserved by painting the pulley side while
running with common paint, afterward applying soft oil or grease.

If a belt slips apply a little oil or soap to the pulley side.

Q. How does the capacity of belts vary?

A. In proportion to width and also to the speed. Double the width and
you double the capacity; also, within a certain limit, double the
speed and you double the capacity. A belt should not be run over 5,000
feet per minute. One four-inch belt will have the same capacity as two
two-inch belts.

Q. How are piston rods and valve rods packed so that the steam cannot
escape around them?

A. By packing placed in stuffing-boxes. The stuffing is of some
material that has a certain amount of elasticity, such as lamp wick,
hemp, soap stone, etc., and certain patent preparations. The packing is
held in place by a gland, as it is called, which acts to tighten the
packing as the cap of the stuffing-box is screwed up.

Q. How would you repack a stuffing-box?

A. First remove the cap and the gland, and with a proper tool take out
all the old packing. Do not use any rough instrument like a file, which
is liable to scratch the rod, for any injury to the smooth surface of
the rod will make it leak steam or work hard.

If patent packing is used, cut off a sufficient number of lengths to
make the required rings. They should be exactly the right length to go
around inside the stuffing-box. If too long, they cannot be screwed up
tight, as the ends will press together and cause irregularities. If
too short, the ends will not meet and will leak steam. Cut the ends
diagonally so that they will make a lap joint instead of a square one.
When the stuffing-box has been filled, place the gland in position and
screw up tight. Afterwards loosen the nuts a trifle, as the steam will
cause the packing to expand, usually. The stuffing-box should be just
as loose as it can be and not allow leakage of steam. If steam leaks,
screw up the box a little tighter. If it still leaks, do not screw up
as tight as you possibly can, but repack the box. If the stuffing-box
is too tight, either for the piston rod or valve steam, it will cause
the engine to work hard, and may groove the rods and spoil them.

If hemp packing is used, pull the fibres out straight and free, getting
rid of all knots and lumps. Twist together a few of the fibres, making
three cords, and braid these three cords together and soak them with
oil or grease, wind around the rod till stuffing-box is sufficiently
full, replace the gland, and screw up as before.

Stuffing-box for water piston of pump may be packed as described above,
but little oil or grease will be needed.

Never pack the stuffing-box too tight, or you may flute the rod and
spoil it.

Always keep the packing in a clean place, well covered up, never
allowing any dust to get into it, for the dust or grit is liable to cut
the rod.




CHAPTER X.

ECONOMY IN RUNNING A FARM ENGINE.


It is something to be able to run a farm engine and keep out of
trouble. It is even a great deal if everything runs smoothly day in
and day out, if the engine looks clean, and you can always develop the
amount of power you need. You must be able to do this before you can
give the fine points of engineering much consideration.

When you come to the point where you are always able to keep out of
trouble, you are probably ready to learn how you can make your engine
do more work on less fuel than it does at present. In that direction
the best of us have an infinite amount to learn. It is a fact that
in an ordinary farm engine only about 4 per cent of the coal energy
is actually saved and used for work; the rest is lost, partly in the
boiler, more largely in the engine. So we see what a splendid chance
there is to save.

If we are asked where all the lost energy goes to, we might reply in
a general sort of way, a good deal goes up the smokestack in smoke or
unused fuel; some is radiated from the boiler in the form of heat and
is lost without producing any effect on the steam within the boiler;
some is lost in the cooling of the steam as it passes to the steam
cylinder; some is lost in the cooling of the cylinder itself after
each stroke; some is lost through the pressure on the back of the
steam valve, causing a friction that requires a good deal of energy
in the engine to overcome; some is lost in friction in the bearings,
stuffing-boxes, etc. At each of these points economy may be practiced
if the engineer knows how to do it. We offer a few suggestions.


THEORY OF STEAM POWER.

As economy is a scientific question, we cannot study it intelligently
without knowing something of the theory of heat, steam and the
transmission of power. There will be nothing technical in the following
pages; and as soon as the theory is explained in simple language, any
intelligent person will know for himself just what he ought to do in
any given case.

First, let us define or describe heat according to the scientific
theory. Scientists suppose that all matter is made up of small
particles called molecules, so small that they have never been seen.
Each molecule is made up of still smaller particles called atoms. There
is nothing smaller than an atom, and there are only about sixty-five
different kinds of atoms, which are called elements; or rather, any
substance made up of only one kind of atom is called an element.
Thus iron is an element, and so is zinc, hydrogen, oxygen, etc. But
a substance like water is not an element, but a compound, since its
molecules are made up of an atom of oxygen united with two atoms of
hydrogen. Wood is made up of many different kinds of atoms united in
various ways. Air is not a compound, but a mixture of oxygen, nitrogen
and a few other substances in small quantities.

The reason why air is a mixture and not a compound is an interesting
one, and brings us to our next point. In order to form a compound,
two different kinds of atoms must have an attraction for each other.
There is no attraction between oxygen and nitrogen; but there is great
attraction between oxygen and carbon, and when they get a chance they
rush together like long separated lovers. Anthracite coal is almost
pure carbon. So is charcoal. Soft coal consists of carbon with which
various other things are united, one of them being hydrogen. This is
interesting and important, because it accounts for a curious thing in
firing up boilers with soft coal. We have already said that water is
oxygen united with hydrogen. When soft coal burns, not only does the
carbon unite with oxygen, but the hydrogen unites with oxygen and forms
water, or steam. While the boilers are cold they will condense the
water or steam in the smoke, just as a cold plate in a steamy room will
condense water from the steamy air, so sweating.

Now the scientists suppose that two or three atoms stick together by
reason of their attraction for each other and form molecules. These
molecules in turn stick together and form liquids and solids. The
tighter they stick, the harder the substance. At the same time, these
molecules are more or less loose, and are constantly moving back and
forth. In a solid like iron they move very little; but a current of
electricity through iron makes the molecules move in a peculiar way. In
a liquid like water, the molecules cling together very loosely, and may
easily be pulled apart. In any gas, like air or steam, the molecules
are entirely disconnected, and are constantly trying to get farther
apart.

Heat, says the scientist, is nothing more or less than the movement
of the molecules back and forth. Heat up a piece of iron in a hot
furnace, and the molecules keep getting further and further apart,
and the iron gets softer and softer, till it becomes a liquid. If we
take some liquid like water and heat it, the molecules get farther and
farther apart, till the water boils, as we say, or turns into steam.
As steam the molecules have broken apart entirely, and are beating
back and forth so rapidly that they have a tendency to push each other
farther and farther apart. This pushing tendency is the cause of steam
pressure. It also explains why steam has an expansive power.

Heat, then, is the movement of the molecules back and forth. There are
three fixed ranges in which they move; the small range makes a solid;
the next range makes a liquid; the third range makes a gas, such as
steam. These three states of matter as affected by heat are very sharp
and definite. The point at which a solid turns to a liquid is called
the melting point. The melting point of ice is 32° Fahr. The point at
which it turns to a gas is called the boiling point. With water that is
212° Fahr. The general tendency of heat is to push apart, or expand;
and when the heat is taken away the substances contract.

Let us consider our steam boiler. We saw that some different kinds of
atoms have a strong tendency to rush together; for example, oxygen
and carbon. The air is full of oxygen, and coal and wood are full
of carbon. When they are raised to a certain temperature, and the
molecules get loose enough so that they can tear themselves away from
whatever they are attached to, they rush together with terrible force,
which sets all surrounding molecules to vibrating faster than ever.
This means that heat is given out.

Another important thing is that when a solid changes to a liquid, or a
liquid to a gas, it must take up a certain amount of heat to keep the
molecules always just so far apart. That heat is said to become latent,
for it will not show in a thermometer, it will not cause anything to
expand, nor will it do any work. It merely serves to hold the molecules
just so far apart.


HOW ENERGY IS LOST.

We may now see some of the ways in which energy is lost. First, the air
which goes into the firebox consists of nitrogen as well as oxygen.
That nitrogen is only in the way, and takes heat from the fire, which
it carries out at the smokestack.

Again, if the air cannot get through the bed of coals easily enough,
or there is not enough of it so that every atom of carbon, etc., will
find the right number of atoms of oxygen, some of the atoms of carbon
will be torn off and united with oxygen, and the other atoms of carbon,
left without any oxygen to unite with, will go floating out at the
smokestack as black smoke. Also, the carbon and the oxygen cannot unite
except at a certain temperature, and when fresh fuel is thrown on the
fire it is cold, and a good many atoms of carbon after being loosened
up, get cooled off again before they have a chance to find an atom of
oxygen, and so they, too, go floating off and are lost.

If the smoke could be heated up, and there were enough oxygen mixed
with it, the loose carbon would still burn and produce heat, and there
would be an economy of fuel. This has given rise to smoke consumers,
and arranging two boilers, so that when one is being fired the heat
from the other will catch the loose carbon before it gets away and burn
it up.

So we have these points:

1. Enough oxygen or air must get into a furnace so that every atom of
carbon will have its atom of oxygen. This means that you must have a
good draft and that the air must have a chance to get through the coal
or other fuel.

2. The fuel must be kept hot enough all the time so that the carbon and
oxygen can unite. Throwing on too much cold fuel at one time will lower
the heat beyond the economical point and cause loss in thick smoke.

3. If the smoke can pass over a hot bed of coals, or through a hot
chamber, the carbon in it may still be burned. This suggests putting
fuel at the front of the firebox, a little at a time, so that its smoke
will have to pass over a hot bed of coals and the waste carbon will be
burned. When the fresh fuel gets heated up, it may be pushed farther
back.

From a practical point of view these points mean, No dead plates in a
furnace to keep the air from going through coal or wood; a thin fire so
the air can get through easily; place the fresh fuel where its smoke
will have a chance to be burned; and do not cool off the furnace by
putting on much fresh fuel at a time.

(Later we will give more hints on firing.)


HOW HEAT IS DISTRIBUTED.

We have described heat as the movement of molecules back and forth at a
high rate of speed. If these heated molecules beat against a solid like
iron, its molecules are set in motion, one knocks the next, and so on,
just as you push one man in a crowd, he pushes the next, and so on till
the push comes out on the other side. So heat passes through iron and
appears on the other side. This is called “conduction.”

All space is supposed to be filled with a substance in which heat,
light, etc., may be transmitted, called the ether. When the molecules
of a sheet of iron are heated, or set vibrating, they transmit the
vibration through the air, or ether. This is called “radiation.” Heat
is “conducted” through solid and liquid substances, and “radiated”
through gases.

Now some substances conduct heat readily, and some do so with the
greatest difficulty. Iron is a good conductor; carbon, or soot on the
flues of a boiler, and lime or scale on the inside of a boiler, are
very poor conductors. So the heat will go through the iron and steel to
the water in a boiler quickly and easily, and a large per cent of the
heat of the furnace will get to the water in a boiler. When a boiler is
old and is clogged with soot and coated with lime, the heat cannot get
through easily, and goes off in the smokestack. The air coming out of
the smokestack will be much hotter; and that extra heat is lost.

Iron is a good radiator, too. So if the outer shell of a boiler is
exposed to the air, a great deal of heat will run off into space and be
lost. Here, then, is where you need a non-conductor, as it is called,
such as lime, wood, or the like.

Economy says, cover the outside of a boiler shell with a non-conductor.
This may be brickwork in a set boiler; in a traction boiler it means
a jacket of wood, plaster, hair, or the like. The steam pipe, if it
passes through outer air, should be covered with felt; and the steam
cylinder ought to have its jacket, too.

At the same time all soot and all scale should be scrupulously cleaned
away.


PROPERTIES OF STEAM.

As we have already seen, steam is a gas. It is slightly blue in color,
just as the water in the ocean is blue, or the air in the sky.

We must distinguish between steam and vapor. Vapor is small particles
of water hanging in the air. They seem to stick to the molecules
composing the air, or hang there in minute drops. Water hanging in the
air is, of course, water still. Its molecules do not have the movement
that the molecules of a true gas do, such as steam is. Steam, moreover,
has absorbed latent heat, and has expansive force; but vapor has no
latent heat, and no expansive force. So vapor is dead and lifeless,
while steam is live and full of energy to do work.

When vapor gets mixed with steam it is only in the way; it is a sort of
dead weight that must be carried; and the steam power is diminished by
having vapor mixed with it.

Now all steam as it bubbles up through water in boiling takes up with
it a certain amount of vapor. Such steam is called “wet” steam. When
the vapor is no longer in it, the steam is called “dry” steam. It is
dry steam that does the best work, and that every engineer wants to get.

While water will be taken up to great heights in the air and form
clouds, in steam it will not rise very much, and at a certain height
above the level of the water in a boiler the steam will be much drier
than near the surface. For this reason steam domes have been devised,
so that the steam may be taken out at a point as high as possible above
the water in the boiler, and so be as dry as possible. Also “dry tubes”
have been devised, which let the steam pass through many small holes
that serve to keep back the water to a certain extent.

However, there will be more or less moisture in all steam until it
has been superheated, as it is called. This may be done by passing it
through the hot part of the furnace, where the added heat will turn all
the moisture in the steam into steam, and we shall have perfectly dry
steam.

The moment, however, that steam goes through a cold pipe, or one cooled
by radiation, or goes into a cold cylinder, or a cylinder cooled by
radiation, some of the steam will turn to water, or condense, as it is
called. So we have the same trouble again.

Much moisture passing into the cylinder with the steam is called
“priming.” In that case the dead weight of water has become so great as
to kill a great part of the steam power.


HOW TO USE THE EXPANSIVE POWER OF STEAM.

We have said that the molecules in steam are always trying to get
farther and farther apart. If they are free in the air, they will soon
scatter; but if they are confined in a boiler or cylinder they merely
push out in every direction, forming “pressure.”

When steam is let into the cylinder it has the whole accumulated
pressure in the boiler behind it, and of course that exerts a strong
push on the piston. Shut off the boiler pressure and the steam in the
cylinder will still have its own natural tendency to expand. As the
space in the cylinder grows larger with the movement of the piston from
end to end, the expansive power of the steam becomes less and less,
of course. However, every little helps, and the push this lessened
expansive force exerts on the piston is so much energy saved. If the
full boiler pressure is kept on the piston the whole length of the
stroke, and then the exhaust port is immediately opened, all this
expansive energy of the steam is lost. It escapes through the exhaust
nozzle into the smokestack and is gone. Possibly it cannot get out
quickly enough, and causes back pressure on the cylinder when the
piston begins its return stroke, so reducing the power of the engine.

To save this the skilled engineer “notches up” his reverse lever, as
they say. The reverse lever controls the valve travel. When the lever
is in the last notch the valve has its full travel. When the lever is
in the center notch the valve has no travel at all, and no steam can
get into the cylinder; on the other side the lever allows the valve to
travel gradually more and more in the opposite direction, so reversing
the engine.

As the change from one direction to the other direction is, of course,
gradual, the valve movement is shortened by degrees, and lets steam
into the cylinder for a correspondingly less time. At its full travel
it perhaps lets steam into the cylinder for three-quarters of its
stroke. For the last quarter the work is done by the expansive power of
the steam.

Set the lever in the half notch, and the travel of the valve is so
altered that steam can get into the cylinder only during half the
stroke of the piston, the work during the rest of the stroke being done
by the expansive force of the steam.

Set the lever in the notch next to the middle notch, or the quarter
notch, and steam will get into the cylinder only during a quarter of
the stroke of the piston, the work being done during three-quarters of
the stroke by the expansive force of the steam.

Obviously the more the steam is expanded the less work it can do. But
when it escapes at the exhaust there will be very little pressure to be
carried away and lost.

Therefore when the load on his engine is light the economical engineer
will “notch up” his engine with the reverse lever, and will use up
correspondingly less steam and save correspondingly more fuel. When the
load is unusually heavy, however, he will have to use the full power of
the pressure in the boiler, and the waste cannot be helped.


THE COMPOUND ENGINE.

The compound engine is an arrangement of steam cylinders to save the
expansive power of steam at all times by letting the steam from one
cylinder where it is at high pressure into another after it exhausts
from the first, in this second cylinder doing more work purely by the
expansive power of the steam.

The illustration shows a sectional view of a compound engine having two
cylinders, one high pressure and one low. The low pressure cylinder is
much larger than the high pressure. There is a single plate between
them called the center head, and the same piston rod is fitted with two
pistons, one for each cylinder. The steam chest does not receive steam
from the boiler, but from the exhaust of the high pressure cylinder.
The steam from the boiler goes into a chamber in the double valve, from
which it passes to the ports of the high pressure cylinder. At the
return stroke the exhaust steam escapes into the steam chest, and from
there it passes into the low pressure cylinder. There may be one valve
riding on the back of another; but the simplest form of compound engine
is built with a single double valve, which opens and closes the ports
for both cylinders at one movement.

[Illustration: WOOLF TANDEM CYLINDER.]

Theoretically the compound engine should effect a genuine economy. In
practice there are many things to operate against this. Of course if
the steam pressure is low to start with, the amount of pressure lost in
the exhaust will be small. But if it is very high, the saving in the
low pressure cylinder will be relatively large. If the work can be done
just as well with a low pressure, it would be a practical waste to keep
the pressure abnormally high in order to make the most of the compound
engine.

An engine must be a certain size before the saving of a compound
cylinder will be appreciable. In these days nearly all very large
engines are compound, while small engines are simple.

Another consideration to be taken into account is that a compound is
more complicated and so harder to manage; and when any unfavorable
condition causes loss it causes proportionately more loss on a compound
than on a simple engine. For these and other reasons compound engines
have been used less for traction purposes than simple engines have.
It is probable that a skilled and thoroughly competent engineer, who
would manage his engine in a scientific manner, would get more out of
a compound than out of a simple; and this would be especially true
in regions where fuel is high. If fuel is cheap and the engineer
unskilled, a compound engine would be a poor economizer.


FRICTION.

We have seen that the molecules of water have a tendency to stick in
the steam as vapor or moisture. All molecules that are brought into
close contact have more or less tendency to stick together, and this is
called friction. The steam as it passes along the steam pipe is checked
to a certain extent by the friction on the sides of the pipe. Friction
causes heat, and it means that the heat caused has been taken from some
source of energy. The friction of the steam diminishes the energy of
the steam.

So, too, the fly wheel moving against the air suffers friction with
the air, besides having to drive particles of air out of its path. All
the moving parts of an engine where one metal moves on another suffer
friction, since where the metals are pressed very tightly together they
have more tendency to stick than when not pressed so tightly. When
iron is pressed too tightly, as under the blows of a hammer in a soft
state, it actually welds together solidly.

There is a great deal of friction in the steam cylinder, since the
packing rings must press hard against the walls of the cylinder to
prevent the steam from getting through. There is a great deal of
friction between the D valve and its seat, because of the high steam
pressure on the back of the valve. There is friction in the stuffing
boxes both of the valve and the piston. There is friction at all the
bearings.

There are various ways in which friction may be reduced. The most
obvious is to adjust all parts so nicely that they will bind as little
as possible. The stuffing-boxes will be no tighter than is necessary to
prevent leaking of steam; and so with the piston rings. Journal boxes
will be tight enough to prevent pounding, but no tighter. To obtain
just the right adjustment requires great patience and the keen powers
of observation and judgment.

The makers of engines try to reduce friction as much as possible by
using anti-friction metals in the boxes. Iron and steel have to be used
in shafts, gears, etc., because of the strength that they posse

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