The Wico igniter produces a spark simila_Practical Hand Book of Gas, Oil and Steam Engines Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel.

high tension magneto except that the heat of the spark is independent of

the engine speed. In other respects it is very different from the types

described in the preceding pages for its motion is reciprocating instead

of being rotary, and because all of the wire is stationary, the only

movement being that of the iron core that passes through the center of

the fields. The fact that the spark is of the same intensity at all

speeds makes this device particularly desirable in starting the engine

at which time the mixture is always of the poorest quality.

[Illustration:

Fig. 113. Wico Igniter. High Tension Reciprocating Type.

]

It is very simple, and is without condensers, contact points or primary

windings, and has no parts that require adjustment.

The current is generated by the reciprocating movement of two soft iron

armatures shown as a bar across the bottom of the two coils, which move

alternately into and out of contact with the ends of the soft iron

cores. The movement of these armatures in the upward direction is

produced by the motion of the engine and the speed of this movement is,

of course, proportional to the speed of the engine. The downward

movement, which produces the spark, is caused by the action of a spring,

is much more rapid than the upward movement and entirely independent of

the speed of the engine.

The magnets are made of tungsten steel, shown as two bars across the top

of the coils, hardened and magnetized and are fastened by machine screws

to the cast iron pole pieces, which serve to carry the magnetic lines of

force from the poles of the magnets to the soft iron cores. The cores,

which fit into slots milled in the pole pieces, are laminated or built

up of thin sheets of soft iron, each sheet being a continuous piece, the

full length of the core. Each core, extends from just below the top

armature, down through the pole piece, and coil to just above the bottom

armature.

Each armature consists of a number of laminations or sheets of soft iron

mounted on a spool shaped bushing, which, in turn, is loosely fitted

onto the squared end of the armature bar. The armature bar is supported

with a sliding fit in a box shaped guide which is fastened in the case.

On the outer ends of the armature bar are spiral springs held in place

by cup shaped washers and retaining pins, the combination making a

self-locking fastening similar to the familiar valve spring fastening

used almost universally on gas engines. These springs bear against the

armatures and tend to force them against the shoulders of the armature

bar.

The coils each have a simple high tension winding of many turns,

thoroughly insulated and protected against mechanical injury. They are

connected together in series by means of a metal strip, thus making one

continuous winding. In the single cylinder igniter, one end of the

winding is grounded to the case of the igniter, while the other end is

connected to the heavily insulated lead wire. This lead wire passes out

through a stuffing box, packed with wicking and thoroughly water tight,

direct to the spark plug in the cylinder.

In the two cylinder machine no ground connection is used, but both ends

of the winding are connected to lead wires passing out of the case to

the spark plugs.

The action of the igniter is as follows:—As the driving bar, through its

connection with the engine, is moved downward to its limit of travel,

carrying the latch with it, the shoulder on the side of the latch snaps

under the head of the latch block. As the motion reverses the latch

carries the latch block and armature bar upward. The lower armature,

being in contact with the stationary cores, cannot rise with the

armature bar, but the lower armature spring is compressed between its

retaining washer and the armature, while the bar rises and carries with

it the upper armature, which bears against the upper shoulders on the

bar.

As the driving bar continues its upward motion the upper end of the

latch meets the lower end of the timing wedge and, as the wedge is held

stationary by the timing quadrant, a further movement of the latch

causes it to be pushed aside until the shoulder on the latch clears the

latch block and releases it.

As the lower armature spring is at this time exerting a pressure between

the armature bar and cores through the medium of the lower armature, the

instant the latch block is released, the armature bar is quickly pulled

downward, carrying the upper armature with it. Just before the motion of

the upper armature is stopped by its coming in contact with the cores,

the lower shoulders on the armature bar come in contact with the lower

armature, and, as the bar has acquired considerable velocity, its

momentum carries the lower armature away from the cores against the

pressure of the upper armature spring, which thus acts as a buffer to

gradually stop the movement of the armature bar. The armature bar

finally settles in a central position.

The timing of the spark is accomplished by releasing the armature bar

earlier or later in the stroke. This is done by shifting the position of

the eccentric timing quadrant, which in turn varies the position of the

wedge so that the latch strikes it earlier or later in the stroke. The

timing quadrant is furnished with several notches into one of which the

top of the wedge rests, thus holding the quadrant in the desired

position.

The motion should preferably be taken from an eccentric on the cam shaft

of a single cylinder four cycle engine, or the crank shaft of a single

cylinder two cycle or a two cylinder four cycle engine. On a two

cylinder four cycle engine, it is sometimes more convenient to drive the

igniter from the cam shaft, using a two throw cam to produce the

required number of sparks. In this case the shape of the cam should be

such as to duplicate the motion of the eccentric. That is, it should

start the driving bar slowly from its lower position, move it most

rapidly at mid stroke and bring it to rest gradually at the upper end of

the stroke, exactly as is done by the eccentric motion.

When an eccentric is already on the engine the motion may be taken from

it to an igniter with a driving bar through a properly proportioned

lever that will give the required length of stroke. Where a plunger pump

is used on the engine the motion can usually be taken from the pump rod.

Where an eccentric has to be provided especially for the igniter, the

driving bar is generally used with its roller running on the eccentric.

(104) Starting On Magneto Spark.

A four-cylinder engine in good condition will come to rest with the

pistons approximately midway on the stroke and balanced between the

compression of the compressing cylinder and of the power cylinder. When

the cylinders of such an engine are charged with a proper mixture, the

engine will start by the ignition of the mixture contained in the

compressing cylinder, for the pressure produced by the ignited gas will

be sufficient to rotate the crankshaft.

[Illustration:

Fig. 114. Bosch Dual System.

]

It is essential, for the ignition system to be so arranged that a spark

can be produced at any point in the piston travel, and in this the Bosch

dual, duplex and two independent systems are successful.

The Bosch dual system, Fig. 114, is part of the equipment of many of the

cars and engines marketed, and is composed of two separate and distinct

ignition systems, one supplying ignition by direct high-tension magneto,

and the other by a battery and high-tension coil. These two systems

consist in reality of but two main parts; the dual magneto,

incorporating a separate battery timer, and the single unit dual coil

with its battery. The sparking current from either battery or magneto is

brought to the magneto distributor, so that the only parts used in

common are the distributor and the spark plugs; the common use of the

latter for both magneto and battery systems is cause for the popularity

of the dual system for motors having provision for only one set of

plugs.

In both the magneto and the battery sides the spark is produced on the

breaking of the circuit, and the coil is so arranged that by pressing a

button when the switch is in the battery position, an intense vibrator

spark is produced in the cylinder during that period when the circuit

breaker is open, which will be the case during the first three-fourths

of the power stroke. The current is transmitted to the distributor and

passes through the spark plug of the cylinder that is on the power

stroke.

[Illustration:

Fig. 115. Bosch Duplex Breaker.

]

Should the engine come to a stop in such a position that the battery

timer is closed, it will not be possible to produce a vibrator spark by

the pressing of the button, but the releasing of the button will produce

a single contact spark that will ignite the mixture and thus start the

engine.

Thus if the engine should stop in some odd position, and the spark is

produced when the piston is slightly before top center, for instance,

there will be a slight reverse impulse which will bring another cylinder

on the power stroke and into the ignition circuit. The engine will

thereupon take up its cycle in the proper direction.

In the Bosch duplex system the coil is in series with the magneto

armature, but the spark is produced under the same condition, that is,

on the breaking of the circuit. In consequence the Bosch duplex system

will permit the production of a spark during the first three-quarters of

the power stroke by the pressing of the push button set on the switch

plate.

[Illustration:

The Herz High Tension Magneto in Which the Magnets are Built up of

Thin Steel Plates Without Pole Pieces (Four Cylinder Type).

]

The Bosch two independent system is composed of a separate Bosch battery

system and a separate Bosch magneto. Although the operation of the coil

is somewhat similar to that of the dual system, the nature of the

battery system is such as to require arrangements for two separate sets

of spark plugs. The coil is not unlike that supplied with the dual

system in that by pressing a button located on the switch plate a series

of intense sparks may be produced in the cylinder at all advantageous

points of the power stroke.

CHAPTER IX

CARBURETORS

(105) Principles of Carburetion.

The carburetor is a device for converting volatile liquid fuels, such as

gasoline, alcohol, kerosene, etc., into an explosive vapor. Besides

vaporizing the liquid, the carburetor also controls the proportion of

the fuel to the air required for its combustion. The mixture produced by

the carburetor must be a uniform gas and not a simple spray to

accomplish the best results for complete and instantaneous combustion.

Proper combustion cannot be attained with any of the fuel in a liquid

state as all of the fuel contained in a liquid particle cannot come into

contact with the consuming air. It is of the utmost importance to have

the air and fuel in correct proportions so that the fuel may be

completely consumed without danger of interfering with the ignition by

an excess of air.

With few exceptions modern gasoline carburetors are of the nozzle type

in which the liquid is broken up into an extremely fine subdivided state

by the suction of the engine piston. This fine spray is then fully

vaporized or gasified by the heat drawn from the surrounding intake air

that is drawn through the carburetor and into the cylinder on the

suction stroke. Owing to the low grade fuels now on the market and to

the constantly varying atmospheric conditions it is seldom possible to

obtain a perfect vapor in the correct proportions, and for this reason

much heat is lost that would be available were the mixture perfect.

Carburetors for automobiles and boats vary in detail from those used on

stationary engines due principally to the difference in matters of

speed. A stationary engine runs at a constant speed which makes

adjustment comparatively easy, while automobile engines have a wide

range of speeds and loads making it very difficult to maintain the

correct mixture at all points in the range. The difference in the fuel

and air adjustments for varying of speeds marks the principal difference

between stationary and automobile carburetors. There are many types of

successful carburetors on the market, so many in fact that we have room

for the description of only three or four of the most prominent, but we

will say that the well known carburetors are based on the same

principles and differ only in matters of detail.

A cross-sectional view of the well known Schebler Type D carburetor is

shown by Fig. 116, and is of the type commonly used on automobile motors

and boats.

[Illustration:

MODEL “D”

Fig. 116. Cross-Section Through Type “D” Schebler Carburetor.

]

(106) Schebler Carburetor.

The carburetor is connected to the intake of the engine by pipe screwed

into the opening =R=, the gas passing from the carburetor to the engine

through this opening.

=D= is the spray nozzle which opens into the float chamber =B=, the

opening of the nozzle being regulated by needle valve =E= which controls

the quantity of gasoline flowing into the mixing chamber =C=.

On the suction stroke of the engine, air is drawn through the upper left

hand opening, past the partially open auxiliary air valve =A=, past the

needle valve =D=, through the mixing chamber =C=, and into the engine

through =R=.

The suction of the engine produces a partial vacuum in the mixing

chamber =C= which causes the gasoline to issue from the nozzle =D=, in

the form of a fine spray which is taken up by the air passing through

the passage =H=, and is taken into the engine through =R=, thoroughly

mixed. The amount of mixture entering the engine, and consequently the

engine speed is regulated by the throttle valve =K=, operated by the

lever =P=.

In order that the amount of spray given by the nozzle =D= be constant it

is necessary that the level, or height of the gasoline in the nozzle be

constant. The level is maintained by means of the float =F=, which

opens, or closes the gasoline supply valve =H=, opening it and allowing

gasoline to enter when the level is low, and closing the valve when the

level is high.

The carburetor is connected to the gasoline supply tank, by pipe

connected to the inlet =G=, through which the gasoline flows into the

float chamber =B=. The float chamber carries a small amount of gasoline

on which the float =F= rests. The richness of the mixture is controlled

by opening or closing the nozzle needle valve =E=, which passes through

the center of the nozzle =D=.

The float =F= surrounds the nozzle in order to keep the level of the

liquid constant when the carburetor is tilted out of the horizontal by

climbing hills, or by the rocking of the boat when used on a marine

engine.

A drain cock =T= is placed at the bottom of the float chamber for the

purpose of removing any water, or sediment that may collect in the

bottom of the float chamber.

At low speeds, the auxiliary air valve =A= lies tight on its seat,

allowing a constant opening for the incoming air through the space shown

at the bottom of the valve.

When the speed of the engine is much increased, the vacuum is increased

in the mixing chamber =C=, which overcomes the tension of the air valve

spring =O= and allows the valve to open and admit more air to the mixing

chamber. The action of the auxiliary air valve keeps the mixture uniform

at different engine speeds, as it tends to keep the vacuum constant in

the mixing chamber.

When the engine speed increases, the flow of gasoline is greater, and

consequently more air will be required to burn it; this additional air

is furnished by the automatic action of the valve, and when once

adjusted, compensates accurately for the different engine speeds.

The gasoline is generally supplied by a tank elevated at least six

inches above the level of the fluid in the float chamber; although in

some cases the gasoline is supplied by air pressure on a tank situated

below the level of the carburetor.

In some types of Schebler carburetors, the float chamber =B= is

surrounded by a water jacket that is supplied with hot water from the

cylinder jackets of the engine. This keeps the gasoline warm so that it

evaporates readily under any atmospheric conditions.

The quantity of air admitted to the carburetor is controlled by an air

valve shown in the air intake by the dotted lines. This is adjusted by

hand for a particular engine and is seldom touched afterward.

When starting the engine it is necessary to have a very rich mixture for

the first few revolutions, this mixture being obtained by “flooding” the

carburetor.

On the Schebler carburetor the mixing chamber is flooded by depressing

the “tickler” or flushing pin =V=.

(107) Two Cycle Carburetors.

Nearly any type of carburetor can be used on a two port, two stroke,

cycle engine providing a check valve is placed between the crank case

and carburetor to prevent the crank-case compression from forcing its

contents back through the inlet passages. A great many manufacturers

make special carburetors for two stroke motors that have the check valve

built into the carburetor itself. With three port two stroke cycle

engines a check valve is not necessary as the piston in this type of

engine performs this duty.

In that class of vaporizers known as mixing valves, the valve that

controls the flow of gasoline blocks the air passage in such a way that

an additional check valve is not necessary.

(108) Kingston Carburetors.

The Kingston Carburetor shown by Fig. 117 differs from the Schebler in

many details, the principal difference being in the construction of the

spray nozzle and the construction of the auxiliary air valve. The

throttle valve E controls the exit of the mixture through the engine

connection C which is an extension of the mixing chamber. The spray

nozzle J which is surrounded by a hood or tube is controlled by the

needle valve A which is threaded into the top of the mixing chamber,

this latter adjustment being locked into place by a button head screw

and a slot in the casting.

[Illustration:

Fig. 117. Cross-Section Through Kingston Carburetor Showing Balls Used

for Auxiliary Air Valves.

]

Surrounding the nozzle tube or hood is a curved restriction in the air

intake passage, is known as a Venturi tube, which insures a constant

relation between the air and fuel supplies. As the action of the Venturi

tube is rather complicated, it will not be taken up in detail. Air is

supplied to the Venturi passage through the intake (D). An annular float

(K) surrounds the mixing chamber that acts on the gasoline supply valve

(I) through a short lever arm. This valve is accessible for cleaning on

the removal of the cap H that covers the valve chamber. Gasoline enters

the float chamber through the fuel pipe G, and enters the spray nozzle

through the two ports in the base of the mixing chamber.

The auxiliary air valve is a particularly novel feature of this

carburetor, as no springs nor disc valves are used in its construction.

Five balls (M) of different weights and sizes act as air valves, the

balls covering the inlet ports (L) under normal operation. As the speed

increases, the balls are lifted off their seats in order of their weight

or size by the increase in suction. With a slight increase of suction,

the lightest ball covering the smallest hole is lifted first, a further

increase in suction lifts the next largest ball which still further

increases the auxiliary air intake, and so on until at the highest speed

all of the balls are off their seats. Access to the ball valves is had

through the valve caps (N). The constant supply inlet is circular and

may be set at any desired angle, as can the float chamber and gasoline

supply connection. Control and adjustment are entirely by the needle

valve.

(109) The Feps Carburetor.

The Feps carburetor has the main needle valve surrounded by a Venturi

chamber as in the preceding case, the needle valve adjustment being made

through a lever on the left of the mixing chamber. An auxiliary nozzle

directly under the auxiliary air valve at the right, connects with the

float chamber and furnishes an additional mixture of gasoline and air

for hill climbing and high speed work when the leather faced auxiliary

air valve lifts from its seat. The adjustment for this auxiliary jet is

shown at the right of the air valve chamber.

For intermediate speeds, the air valve alone is in action. No

controlling springs are used on the air valve which insures positive

action and sensitive control of the air. A float surrounding the Venturi

tube controls the fuel valve through the usual lever arm. A wire gauze

strainer placed in the fuel chamber to the left prevents dirt and water

from being drawn into the nozzle, and as this strainer easily removed it

is a simple matter to clean and prevent the troubles due to dirty fuel.

By closing the upper valve in the vertical engine connection the vacuum

is increased in the manifold when starting the engine. This increase of

vacuum draws gasoline from the float chamber and primes the engine

making the engine easy to start in cold weather. The tube through which

the gasoline is drawn for priming is the small crooked tube bending over

the float and terminating above the starting valve. Below this valve is

the throttle valve which controls the mixture in the ordinary manner.

The adjustment for intermediate speeds is made by the center knurled

thumb-screw shown over the air valve chamber which controls the travel

of auxiliary air valve. In effect this is a double carburetor, one jet

for high speed and one for low.

(111) Gasoline Strainers.

Much trouble is caused in carburetors by dirt, water and sediment,

collecting in the small passages and obstructing the flow of the

gasoline.

[Illustration:

Fig. 119. The Excelsior Carburetor in Which the Air is Regulated by a

Ball which Lies in the Tapering Venturi Tube. An Increase of Suction

Lifts the Ball and Allows More Air to Pass.

]

The purpose of the gasoline strainer is to prevent any water or foreign

matter from being carried into the carburetor, and this device should be

used on every engine if the owner wishes to be free from carburetor

troubles.

(112) Installing Gasoline Carburetors.

(1) Use brass or copper pipe from the tank to carburetor if possible to

avoid trouble from dirt and flakes of rust.

(2) When installing a gasoline tank be sure that the bottom of the tank

is at least six inches above the carburetor to insure a good flow.

(3) The tank should be provided with an air vent hole, or the gasoline

will not flow because of the vacuum in the top of the tank.

(4) All tanks should be provided with a drain cock at the lowest point

so that water and dirt may be easily removed.

(5) Clean out the tank thoroughly before filling with gasoline to avoid

clogged carburetors.

(6) Pipes from the tank to carburetor should never be placed near

exhaust pipes or hot surfaces for the gasoline vapor may prevent the

feeding of gasoline.

(7) Clean out pipes before using.

(8) If common threaded pipe joints are used on the gasoline piping, use

common soap in place of red lead.

(113) Installing the Carburetor.

The carburetor should be placed as near to the cylinder as possible, the

shorter the pipe, the less the amount of vapor condensed in the

manifold. With multi-cylinder engines the carburetor should be so

situated, that is, an equal distance from each cylinder, so that each

cylinder will inhale an equal amount of vapor.

The intake opening of the pipe should be placed near one of the

cylinders, or draw warm air off the surface of the exhaust pipe in order

that gasoline will evaporate readily in cold weather, and form a uniform

mixture at varying temperatures.

Great care should be taken to prevent any air leaks in the carburetor,

or intake manifold connections, as a small leak will greatly reduce the

strength of the mixture and cause irregular running. Always use a gasket

between the valves of a flanged connection and keep the bolts tight. If

a brazed sheet brass manifold is used, look out for cracks in the

brazing.

Leaks may be detected in the connections by spurting a little water on

the joints, and turning the engine over on the suction stroke. If the

water is sucked in the leaks should be repaired at once. Make sure when

placing gaskets, that the gasket does not obstruct the opening in the

pipe, and that it is securely fastened so that it is not drawn in by the

suction.

Never allow the carburetor to support any weight, as the shell is easily

sprung which will result in leaking needle valves.

=CARBURETOR ADJUSTMENT.= When adjusting the carburetor of multiple

cylinder engine, it is advisable to open the muffler cutout in order

that the character of the exhaust may be seen or heard. With the muffler

open, the color of the exhaust should be noted. With a =PURPLE= flame

you may be sure that the adjustment is nearly correct for that load and

speed; a yellow flame indicates too much air; a thin blue flame too much

gasoline, and is not the best for power.

Before starting for the adjustment test, try the compression, and the

spark. If the compression is poor, try the effects of a little oil on

the piston, which may be introduced into the cylinder through the

priming cup. It will be well to dilute the oil to about one-half with

kerosene. After all trouble with all the parts are clear, you may start

the engine.

Turn on the gasoline at the tank, and after standing a moment see

whether there is any dripping at the carburetor, if there is, the

trouble will probably be due to a leaky float, dirt in the float valve,

or to poor float adjustment. Locate the leak and remedy it before

proceeding further. Dirt on the seat of the needle valve may sometimes

be removed by “flooding” the carburetor, which is done by holding down

the “tickler” lever for a few seconds, causing the gasoline to overflow,

and wash out the dirt.

If the motor has been standing for a time it would be well to “prime”

the motor by admitting a little gasoline into the cylinder through the

priming cup, or by pushing the tickler a couple of times so as to

slightly flood the carburetor.

Now turn on the spark and turn over the engine for the start, taking

care that the throttle is just a little farther open than its fully

closed position. If the engine takes a few explosions and stops, you

will find the nozzle, or that some part of the fuel piping is clogged

which will stop the engine. If the motor gradually slows down, and

stops, with =BLACK SMOKE= issuing from the end of the exhaust pipe, or

=MISFIRES= badly, the mixture is =TOO RICH=, and should be reduced by

cutting down the gasoline supply by means of the needle valve adjusting

screw. If it stops quickly, with a =BACKFIRE=, or explosion at the

supply of gasoline should be =INCREASED= by adjusting the mouth of the

carburetor, the mixture is =TOO LEAN=, and the needle valve.

In all cases be sure that the auxiliary valves are closed when the

engine is running slowly, with the throttle closed, as in the above

test. If they are open at low speed, the mixture will be weakened and

the test will be of no avail.

After adjusting the needle valve as above until the engine is running

(with throttle in the same partially closed position), turn the valve

slowly in one direction or the other until the motor seems to be running

at its best. During the above tests the spark should be left retarded

throughout the adjustment, and the throttle should not be moved.

The carburetor should now be tested for high speed adjustment, by

opening the throttle wide (spark ¼ advanced), and observing the action

of the motor. If the engine back-fires through the carburetor at high

speed, it indicates that the mixture is too weak which may be due to the

auxiliary air valve spring tension being too weak and allowing an excess

of air to be admitted. Increase the tension of the spring, and if this

does not remedy matters, admit a little more fuel to strengthen the

mixture by means of the needle valve adjustment. Do not touch the needle

valve if you can possibly avoid it, or the high-speed adjustment, as the

fuel adjustment will be disturbed for low speed.

If the engine misfires, with loud reports at the exhaust, does not run

smoothly, or emits clouds of black smoke at high speed, the engine is

not receiving enough air in the auxiliary air valve, consequently the

tension of the spring should be reduced.

Back firing through the carburetor denotes a weak mixture.

Trouble in cold weather may be caused either by slow evaporation of the

gasoline, or by water in the fuel that freezes and obstructs the piping

or nozzle. In cold weather a higher gravity of gasoline should be used

than in summer, as it evaporates more readily, and therefore forms a

combustible gas the rate at lower temperatures.

To increase the rate of evaporation of the gasoline, it should be placed

in a bottle and held in hot water for a time before pouring it into the

carburetor or tank, or the air inlet warmed with a torch.

The cylinder water jacket should always be filled with hot water before

trying to start the engine, and will prevent the gas from condensing on

the cold walls of the cylinder. Often good results may be had by

wrapping a cloth or towel around the carburetor, that has been dipped in

hot water.

The cylinder of an air-cooled engine may be warmed by =gently= applying

the heat of a torch to the ribs, or by wrapping hot cloths about it.

The tank, piping, and carburetor should be drained more frequently in

cold weather than in hot, to prevent any accumulation of water from

freezing, and stopping the fuel supply. A gasoline strainer should

always be supplied on the fuel line, and should be regularly drained.

The motor may often be made to start in cold weather by cutting out the

spark, and cranking the engine two or three revolutions with the

throttle wide open. The throttle should now be closed within ⅛ of its

fully closed position, the ignition current turned on, and the engine

cranked for starting. This system will very seldom fail of success at

the first attempt.

Carburetor flooding is shown by the dripping of gasoline from the

carburetor, and which results in too much gasoline in the mixture.

Flooding may be caused by dirt accumulating under float valve, by a

leaking float (Copper Float), by Water Logged Float (Shellac worn off

Cork Float), by float adjustment causing too high a level of gasoline,

by leaking float valve, by cutting out ignition when engine is running

full speed, by rust or corrosion sticking float valve lever, by float

binding in chamber, by float being out of the horizontal, by float valve

binding in guide, by excessive pressure on gasoline, or by tickler lever

held against float continuously.

Dirt accumulated under float valve may sometimes be flushed out by

depressing tickler lever several times; if this does not suffice, the

cap over the valve must be removed, and the orifice cleaned by wiping

with a cloth.

=LEAKING FLOAT VALVES= should be reground with ground glass or very fine

sand; never use emery as the particles will become imbedded in the

metal, which will be the cause of worse leaks.

Should the shellac be worn off of a cork float allowing the gasoline to

penetrate the pores of the cork, a new float should be installed, as it

is a doubtful policy for owner to give the float an additional coat of

shellac.

=MISFIRING AT LOW SPEED.= If the carburetor cannot be adjusted to run

evenly on low speed after making all possible adjustments with the

needle valve, the trouble is probably due to air leaks between the

carburetor and engine, caused by broken gaskets, cracked brazing in the

intake manifold, or by leaks around the valve stem diluting the mixture.

=INCORRECT VALVE TIMING= will cause missing, especially on multiple

cylinder engines, as the carburetor cannot furnish mixture to several

cylinders that have different individual timing. Look for air leaks

around the spark edge openings, and be sure that all valves seat gas

tight. Always be sure that the auxiliary air valve remains closed at low

speeds, as a valve that opens at too low a speed will surely cause

misfiring as it dilutes the mixture.

=MISSING= in one cylinder may be caused by an air leak in that cylinder.

=WATER= in gasoline will cause misfiring, especially in freezing

weather, as it obstructs the flow of fuel to the carburetor. The

carburetor and tank should be drained at regular intervals, and if

possible, a strainer should be introduced in the gasoline line.

=CLOGGED NOZZLE.= Particles of loose dirt in the nozzle will occasion an

intermittent flow of gasoline that will result in misfiring. The nozzle

should be cleaned with a small wire run back and forth throughout the

opening.

=CLOGGED AIR VENT= in the float chamber will change the level of the

fuel, and will either “starve” the engine, or flood the carburetor. The

air in the float chamber is a very small hole, and is likely to clog.

=HOT FUEL PIPE.= If the fuel pipe that connects the tank with the

carburetor, becomes hot, due to its proximity to the exhaust pipe of

cylinders, vapor will be formed in the pipe that will interfere with the

flow of fuel.

=DIRT UNDER AUXILIARY AIR VALVE= will prevent the valve from seating

properly, causing the engine to misfire at low speed.

=CRACKS OR LEAKS= in intake pipe or gaskets will cause intermittent

leaks of air and spasms of misfiring. Old cracks that have been brazed

will sometimes open and close alternately causing baffling cases of

spasmodic misfiring.

=DIRT IN AIR INTAKE= will change the air ratio, and the increased

suction will cause a greater flow of gasoline. Do not place the end of

the inlet pipe in a dusty place, nor where oil can be splashed into it

by the engine. Clean out periodically.

“=LOADING UP=” of the inlet piping in cold weather on light load is

caused by the mixture condensing in the intake pipe. The only remedy is

to keep the piping warm, or to heat the inlet air.

=CLOGGED OVERFLOW PIPE=, with engines equipped with pump supply will

cause flooding, as the fuel does not return rapidly enough to the tank.

(114) Kerosene Vaporizer for Motorcycles.

An ingenious vaporizing device has been designed for the use of kerosene

as a fuel for motorcycle engines, by the M. G. and G. Motor Patents

Syndicate, Ltd., England, is described in Motor Cycling. The device

consists of a comminuter, or vaporizer, which screws into the

sparkling-plug hole in the cylinder, the plug being transferred to an

aperture in the vaporizer, a feeder for regulating the supply of fuel to

the vaporizer, and a throttle and air barrel, or mixing chamber, for the

purpose of proportioning the amount of air and gas supplied to the

engine, and for controlling the speed of the machine as in an ordinary

carburetor.

The feeder receives the fuel—in this case kerosene—although any heavy

oil can be used with almost equally good results. The feeder answers a

purpose similar to the ordinary float chamber of the carburetor, i. e.,

to regulate the amount of kerosene it is required to pass through the

vaporizer. It consists of a small chamber mounted upon the end of a pipe

leading to the vaporizer. Kerosene is fed to this device by a copper

pipe from the tank, and enters at the lowest point through a 3/16-inch

hole or jet. This is covered by a small valve, operated by engine

suction. The lift of this valve can be adjusted by the insertion of

washers to suit any particular size of engine, just as one would use

various size jets to suit either a large or small engine. One of the

greatest advantages of the device lies in the size of this aperture or

jet, inasmuch as it cannot possibly choke up with grit, and even water

will pass through and not stop the operation of the carburetor. At the

top of the feeder is an air hole, which admits just sufficient air to

pass the kerosene through the vaporizer, the reason for this being that

the heat of the vaporizer shall only act upon the fuel, the mixture

afterwards being balanced by air being admitted through the mixing

chamber.

After the kerosene leaves the feeder it passes through a pipe to the

vaporizer. This consists of a gunmetal body with cooling ribs cast on

the outside, whilst through the center runs a thin copper tube of ⅝-inch

diameter and only 20 gauge, which would really melt during the heat of

combustion were it not for the fact of the fuel passing through it. The

heat derived from this formation of vaporizer is approximately 1,000

degrees Fahr. Inside the central tube is a strip-steel spiral, which

serves the double purpose of giving a centrifugal motion to the fuel,

and at the same time forming a supporter for the tube, preventing it

crushing under the force of the explosions. It is, of course, understood

that the inside of the feeding tube is entirely isolated from the

combustion chamber. The sparking plug is screwed into the wall of the

vaporizer, which is now really an extension of the combustion chamber.

Obviously this slightly reduces the compression of the engine, which,

however, is a necessary feature when kerosene is used as a fuel. After

passing through this device the kerosene is thoroughly vaporized, and

the vapor is led through a flexible pipe to the throttle chamber; this

taking the place of an ordinary carburetor and being fitted to the

induction pipe.

There are two slides, operated by Bowden levers from the handle-bar, one

being for the main air intake and the other for the gas.

[Illustration:

Fig. 121-a. The English Aster Electric Lighting Unit.

]

Undoubtedly the greatest claim for this vaporizer is the fact that

practically no carbon deposit forms upon the inside of the cylinder or

on the piston. What little deposit is formed takes the shape of small,

soft flakes, which, instead of adhering to the cylinder walls, break

away before they have attained any size and are blown through the

exhaust valve. Altogether, this device seems to have finally solved the

problem of using kerosene as a fuel on air-cooled engines, especially if

the carbon deposit difficulty has been finally overcome.

The device was fitted to a 3½ h.p. Matchless with a White and Poppe

engine. In order to start up, a small gasoline tank, holding about one

half-pint of gasoline, is fitted under the main tank and communicates

with the feeder. Half a minute is all that is necessary running on

gasoline, when the kerosene can be turned on. The machine would fire at

a walking pace, and could also be accelerated up to 55 m.p.h.

CHAPTER X

LUBRICATION

(116) General Notes on Lubrication.

No matter how carefully the surface of a shaft or bearing may be

finished, there always remains a slight roughness or burr of metal,

which although of microscopic proportions is productive of friction or

wear. Each minute projection of metal on a dry shaft acts exactly as a

lathe tool, when the shaft revolves in cutting a groove in the

stationary bearing. Since there are a multitude of these projections in

a journal, the wear would be very rapid, and would in a short time

completely destroy either the shaft or bearing, no matter how highly

finished in the beginning.

When lubricating oil is introduced into a bearing it immediately covers

the rubbing surface, and as the oil has a considerable resistance to

being deformed, or is “stiff,” it separates the surface of the shaft

from that of the bearing for a distance equal to the thickness of the

oil film. With ordinary lubricants this distance is more than enough to

raise the irregularities of the shaft out of engagement with those of

the bearing. This property of “stiffness” in the oil is known as

“viscosity.” The value of viscosity varies greatly with different grades

of oil, and also with the temperature with the result that the allowable

pressure on the oil per square inch also varies. With oils of low

viscosity a small pressure per square inch on the bearing will squeeze

it out, and allow the two metallic surfaces to come against into

contact, causing wear and friction, while an oil of greater viscosity

will successfully resist the pressure.

The life and satisfactory operation of the engine depends almost

entirely upon the lubricant and the devices that apply it to the

bearings. Excessive wear and change in the adjustments are nearly always

the result of defective lubricating devices or a poor lubricant. The

principal lubricants are:

(1) Solid lubricants such as graphite, soapstone, or mica.

(2) Semi-solid lubricants such as vaseline, tallow, and soap emulsions,

or greases compounded of animal fats, vegetable and mineral oils; and

(3) Liquid lubricants, such as sperm oil, or one of the products of

petroleum, the latter medium being the class of lubricant most suitable

for internal combustion engines, owing to its combining the qualities of

a high flash-point with a comparative freedom from either acidity or

causticity.

Oils of animal or vegetable origin should never be used with gas engine

as the high temperatures encountered will char and render them useless.

Tallow and lard oil are especially to be avoided, at least in a pure

state.

In the cylinder only the best grade of =GAS ENGINE= cylinder oil should

be used, which according to different makers has a flash point ranging

from 500 to 700 degrees. Using cheap oil in the cylinder is an expensive

luxury. In general, the oils having the highest flash points have also

the objectionable tendency of causing carbon deposits in the combustion

chamber and rings which is productive of preignition and compression

leakage. The lower flash oils have a tendency to vaporize and to carry

off with the exhaust which will leave the walls insufficiently

lubricated unless an excessive amount is fed to the cylinder. By

starting with samples of well known brands recommended by the builder of

the engine it will be an easy matter to find which is the cheapest and

gives the best results. In figuring the cost of oil do not take the cost

per gallon as a basis, but the cost for so many hours of running, or

better yet the number of horse-power hours. Unless you are fond of

buying replacements and new parts do not stint on the oil supply.

On the other hand, an excess of oil should be avoided as this means not

only a waste of oil through the exhaust pipe, but trouble with carbon

deposits and ignition troubles as well. Foul igniters, misfiring, and

stuck piston rings are the inevitable result of a flood of lubricating

oil. When a whitish yellow cloud of smoke appears at the end of the

exhaust pipe, cut down the oil feed. The exhaust should be colorless and

practically odorless.

Too much oil cannot be fed to the main bearings of the crank shaft if

the waste oil is caught, filtered and returned to the bearings by a

circulating system, for the flood of oil not only insures ample

lubrication but removes the heat generated as well. The bearings require

a much lighter oil, of a lower fire test than the cylinder oil. It is

evident that its viscosity is a most important element, as it determines

the allowable pressure on the shaft. The viscosity of an oil varies with

the temperature and is greatly reduced at cylinder heat. A comparative

test of the viscosity or load bearing qualities of an oil may be made by

making bubbles with it by means of a clay pipe; the larger the bubble,

the higher the viscosity of the oil.

Different sizes of bearings, and bearing pressures, call for oils of

different viscosities, and consequently an oil that would be suitable

for one engine would not answer for another; heavy bodied oils being

used for heavy bearing pressures, and light thin oil for small high

speed bearings. The best way to determine the value of an oil for a

particular shaft bearing is by experiment, attention being paid to its

adaptability for the feeding devices used.

The compression attained in a gas engine cylinder depends to a certain

extent upon the body of the cylinder oil, for many engines that leak

compression past the rings with thin oil will work satisfactorily with a

heavy viscous oil that clings tightly to the surfaces. An engine will

often lose compression when an oil of poor quality is used.

Air cooled engine cylinders require an oil of heavier body than water

cooled because of the higher temperature of the cylinder walls. Gum and

sticky residue are usually formed by animal oils or adulterants added to

the numeral oil base. Oils containing free acids should be avoided as

they not only corrode and etch the bearing, but also clog the oil pipes

or feeds with the products of the corrosion.

Free acid is left from the refining process, and may be determined by

means of litmus paper inserted into the oil. If the litmus paper turns

red after coming into contact with the oil, acid is present, and the oil

should be rejected.

The following are the characteristics of an oil suitable for use on an

engine:

(a) The oil must be viscous enough to properly support the bearings or

to prevent leakage past the piston rings.

(b) It should be thin enough so that it can be properly handled by the

oil pumps, or drip freely in the oil cups.

the formation of “gum.”

(d) It should contain no free acid.

Ordinarily a good grade of fairly heavy machine oil will be suitable for

use on the bearings of the average engine, such as the cam-shaft and

crank-shaft bearings.

Only very light clean oil, or vaseline should be used on ball-bearings,

as heavy greases and solid lubricants pack in the races and cause

binding or breakages.

Flake graphite is much used as lubricant, and too much cannot be said in

its favor, as it furnishes a smooth, even coat over the shaft, fills up

small scores and depressions, and makes the use of light oil possible

under heavy bearing pressures. With graphite, less oil is used, as the

graphite is practically permanent, and should the oil fail for a time,

the graphite coat will provide the necessary lubrication until the feed

is resumed without danger of a scoring or cutting. In fact, when

graphite is used, the oil simply acts as medium by which the graphite is

carried to the bearings.

If graphite is injected into the cylinder in small quantities it greatly

improves the compression, as it fills up all small cuts and abrasions in

the cylinder walls.

A good mixture to use for bearings is about 1½ teaspoonsful of graphite,

to a pint of light machine oil, thoroughly mixed.

Graphite can be placed in the crank chamber of a splash feed engine, by

means of an insect powder gun.

Trouble with oil cups is always in evidence during cold weather, as the

oil congeals, and does not drip properly into the bearings. The fluidity

of the oil can be increased in cold weather by the addition of about ten

per cent of kerosene to the oil.

If too much oil is fed to the cylinders, the piston rings will be

clogged with gum, and a loss of compression, or a tight piston will be

the result. An excess of oil will short-circuit the igniter or sharp

plugs, and will form a thick deposit in the combustion chamber that will

eventually result in preignition or back-firing. Deposits and gum formed

in the cylinder will cause leaky valves and a loss of compression. Feed

enough oil to insure perfect lubrication, but not enough to cause light

colored smoke at the exhaust.

Lubricating systems may be divided into three principal classes:

Sight-feed, splash system, and the force feed system. Sight feeding by

means of dripping oil cups is too common to require description, and is

used on many stationary engines, both large and small.

The splash system is in general use on small high speed engines both

stationary, and of the automobile type.

The force feed system in which oil is fed under pressure by a pump is by

far the most desirable as the amount of oil fed is given in positive

quantities proportional to the engine speed, and with sufficient

pressure to force it past any ordinary obstructions that may exist in

the oil pipe.

Another system that is half splash, and half force feed, is the pump

circulated system much used in automobiles.

=THE SPLASH FEED SYSTEM= is the simplest of all, as the bearings are

lubricated by the oil spray caused by the connecting rod end splashing

through an oil puddle located in the bottom of the closed crank case.

The piston and cylinder are lubricated by the spray, as well as the

bearings, as the lower end of the piston projects into the crank chamber

at the moment that the connecting rod end strikes the oil puddle.

To maintain constant lubrication, it is necessary that the oil in the

puddle be kept at a constant height, or as in some cases be varied in

such a way that the surface of the puddle is raised and lowered in

proportion to the load on the engine. In the average engine the oil

level is maintained by overflow pipes or openings that allow any excess

of oil over the fixed level to flow back to the pump. In the Knight

engine the puddles are formed in movable cups which are connected with

the throttle in such a way that the opening of the throttle raises the

oil level and supplies more oil to the engine at the greater load, or

speed.

Oil in splash systems is supplied by a low pressure pump, usually of the

rotary type, in the base of the engine. Oil from the pump passes to the

bearings, drops into the puddle, overflows through the overflow opening,

and returns to the pump through a filter, the same oil being used over

and over again until exhausted. This strainer should be removed

occasionally and the dirt removed, for should it be allowed to collect

it is likely to obstruct the oil supply. The oil should be replaced

before it becomes too black or foul, the crank case and bearings

thoroughly cleaned with kerosene, and new oil replaced. The supply may

be interrupted by the failure of the pump, caused by sheared keys or

leakage of air in the suction line due to cracks. It would be well to

run the engine for a few minutes with the kerosene in the crank case, in

order that all of the oil may be removed. See that the drain cock is

closed at the bottom of the cylinder or all of the oil will be lost.

Lock the valve handle carefully so that it cannot jar open. If light

colored smoke appears in intermittent puffs with a multiple cylinder

engine, it indicates that one cylinder is receiving too much oil.

(117) Force Feed Lubricating System.

The force feed system is by far the most reliable of all oiling systems,

as it feeds uniformly and continuously at almost any temperature, and

against the pressure of practically any obstruction in the pipe.

The oil is supplied by a small pump driven from the engine, the pump

being incased in the oil tank housing. Frequently a hand pump is used in

combination with the power pump when starting the engine, or at times

when the power pump is out of service. A single pump is used with any

number of leads, each lead, or feed, having an independent regulating

valve and sight feed, or a pump unit may be provided for each lead,

depending on the size of the engine.

(118) Bosch Force Feed Oiler.

The force feed of the Bosch Oiler is so positive in character, that the

flow of oil is not affected by heavy back-pressure due to elbows and the

diameter of the conducting pipes. Springs, valves and other devices,

which would check the flow of oil, are fundamentally eliminated. The

amount of oil fed may be accurately and permanently regulated. Glands

and other packings and bushings are eliminated. Connecting rods and all

links are eliminated by the direct application of the movements of the

oscillating cam disks to the pump plungers and piston valves.

Each feed of this oiler is provided with a separate pump element

consisting of a pump body plunger and a piston valve, the suction and

feed ducts connecting directly with the pump body of their respective

elements. With this construction, pump elements may be replaced or

added. The oiler requires no attention other than to be supplied with

oil; and the opening and closing of the valves, pet cocks, etc., on

starting and stopping the machine is rendered unnecessary. The correct

and regular operation of the elements may be verified by observation of

the reciprocating movements of the regulating screws.

Each pump plunger is provided with an adjusting screw through which the

feed may be regulated from 0 to 0.2 cubic centimeters for each stroke.

The Bosch Oiler (Fig. 121) being positively driven by the machine that

it supplies, the oil fed is in all cases proportional to the engine

speed; overloads are thus automatically taken care of.

The circular arrangement of the elements of the Bosch Oiler permits the

device to be driven by a single shaft, and the oil is forced through the

feeds from a single reservoir to the required points of application. A

pump element consists of a pump body 1, a pump plunger 2 and a piston

valve 3, and is supported on the base plate 13. The elements are

arranged concentrically about the drive shaft in such a manner that the

pump plungers form a circle around the circle formed by the piston

valves.

[Illustration:

Top View of Bosch Force Feed Oiler.

]

[Illustration:

Fig. 121. Cross-Section Bosch Oiler.

]

The pump cam disk 20 and the valve cam disk 22 are set on the drive

shaft at other than a right angle with its axis, and the rims of the

disks are gripped by slots formed in the heads of the pump plungers and

piston valves. The relation of these cam disks is such that the valve

cam disk is 90° in advance of the plunger cam disk. The valve cam disk

is solid on the drive shaft, but the pump cam shaft is loose and driven

through a lug on the valve cam disk. When the drive of the pump is

reversed, the lug on the valve cam disk frees itself and again takes up

the drive of the pump cam disk, after the drive shaft has made a half

revolution.

Regulating screws 4 are set in the slotted heads of the pump plunger,

and by means of this the back-lash or play of the cam disk may be

regulated. The regulating screws are provided with lock nuts, and

project through the cover of the oil tank housing, being exposed by the

removal of the filler cover 42. The filler opening is provided with a

removable strainer to prevent the entrance of foreign particles into the

oil tank.

Pump shaft 14 is driven through worm gear 23 which meshes with worm 24

on drive shaft 25; drive shaft 25 projects from the oiler housing, and

is coupled with the driving shaft of the machine to be lubricated.

Base plate 13 is attached to the oiler cover by three stud bolts, thus

permitting the removal of the entire oiler mechanism from the housing.

The quantity of oil in the oil tank is shown by gauge glass 44.

On the starting of the machine to which the oiler is attached, the pump

shaft and the cam disks that it supports are set in motion through worm

24 and worm gear 23. A direct reciprocating motion is given to the pump

plunger and to the piston valve by the rotation of the cam disks which

have a movement similar to that of the “wobble saw.” The relation of the

cam disk is such that the piston valve movements are 90° in advance of

the movements of the pump plungers. The pump will run in either

direction without alteration.

To secure this effect a play of 90° is provided between the cam disk.

When cam 22 is driven clockwise, cam disk 20 is driven by the lug which

meshes with a lug on disk 22. The cams are then in such a relation that

the cam valve disk is 90° in advance of the pump cam disk. When

reversed, cam 20 remains at rest until cam 22 catches the lug and cam

20, when the drive continues as before. The cams are then in the same

relation as previously for as the valve disk 22 has traveled through

180° it is evident that it is 90° in advance of the pump disk.

(119) Castor Oil for Aero Engines.

Castor oil is used almost exclusively in the Gnome and other rotary

engines of the same type, but has not been particularly successful on

stationary cylinders.

Chemically, castor oil differs from all other vegetable or animal oils

in containing neither palmitin or olein. It is soluble in absolute

alcohol, but practically insoluble in gasoline. On the other hand, the

castor oil is capable of dissolving small quantities of mineral oil, the

more fluid they are the less it absorbs of them. But the insolubility of

castor oil in mineral oil disappears completely when it is mixed with

even a very small quantity of another vegetable or animal oil, such as

colza or lard oil. An adulteration may thus result in a serious reversal

of the oil’s best qualities; in fact, in serious seizures, Castor oil

does not attack rubber, but it contains 1 to 2 per cent of acid fats;

sometimes more.

“In my opinion says a writer in ‘_Autocar_’ castor oil can only be used

in fixed cylinders with impunity for short distances and then with

repeated cleanings between runs, but on rotary engines of the Gnome type

cleaning is almost unnecessary. The reason is that one cannot

consistently use castor oil over and over again, for the fact is

indisputable that it has a far greater tendency than mineral oils to

absorb oxygen, and so gradually to increase in body and finally to gum.

When once it commences to gum the carbonization becomes more rapid,

because the thickened and pitch-like oil acts as an insulating covering

on the top of the pistons and of the cylinder, and cannot get away with

sufficient rapidity to avoid decomposition and baking to a coke.

Therefore if castor oil is to be used on the ordinary stationary

cylinder type of engine, it is necessary to wash out the crank chamber

and to replace with fresh oil at frequent intervals. On a rotary engine

such as the Gnome this cleaning is unnecessary, because there is a

continuous stream of fresh castor oil brought into the crank chamber and

then thrown by centrifugal force past the pistons and through the

cylinder into the exhaust. Thus the stream of oil never has sufficient

time to oxidize fully, gum or decompose. This action of centrifugal

force accounts for the large consumption of oil on the rotary engine,

and also for the fact that the pistons and cylinders keep comparatively

clean.

“In thus criticizing the use of castor oil I do not wish it to be

inferred that it is not an excellent lubricant. What I wish to suggest

is that in the case of an internal combustion engine it must be made

with discretion. A point in favor of castor oil is the fact that it

maintains its viscosity in a remarkable manner at high temperatures, and

that at those high temperatures it has a peculiar creeping or capillary

action which enables it to spread uniformly over the whole of the

metallic surfaces, whereas under the same conditions a similarly bodied

mineral oil would be unevenly distributed in patches. Another point is

that the specific heat of castor oil is considerably higher than that of

a pure mineral oil. This is in its favor, insomuch that it shows castor

oil to be a better heat remover than a mineral oil.

“Motorists and aviators have from time to time informed me that they are

using castor oil, but have apparently been under some misapprehension. I

find that they have been using a brand of prepared oil under the

impression that it is a specially refined castor oil, or that it is a

blend of castor oil.”

[Illustration:

Producer Gas Engine Plant at Göttingen, Germany, Consisting of Four

3,500 Horse-Power Units.

]

A simple method for testing the purity of castor oil is at the disposal

of all. It is known as the Finkener test. Ten cubic centimeters of

castor oil is placed in a graduate. Five times as much alcohol, 90 per

cent, is added and stirred in. The solution should remain clear and

brilliant at 15 to 20 degrees C. An admixture of foreign oils, even if

only 5 per cent, riles the solution at this temperature, though not

above it.

(120) Force Feed Troubles.

The most common trouble with force feed systems is the failure of the

operator to remove the dirt collected by the strainer. The oil piping

should be cleaned out at least once every year by means of a wire and

gasoline, to remove any gum that may have been deposited. Driving belts

should be kept tight to prevent slipping, and belts that are soaked with

oil should be cleaned with gasoline and readjusted.

Leaking pump valves generally of the ball type are a common cause of

failure. They may leak because of wear or by an accumulation of grit and

dirt on their seats, which prevents the valves from seating properly. If

the valves leak, the oil will be forced back into the tank, or will not

be drawn into the pump cylinder at all, depending on whether the inlet

or discharge valve is the offender. Plunger leakage which is rare will

cause oil failure.

If the oil pipes that lead to the bearings rub against any moving part,

or against a sharp edge, a hole will be worn in the pipe, a leak caused

which will prevent the oil from reaching the bearing. A dented or

“squashed” pipe will prevent the flow of oil.

The set screw or pin holding the pulley to the pump shaft may loosen and

cause it to run idly on the shaft without turning the pump. This will of

course, prevent the circulation of oil.

The worm and worm wheel may wear so that the pump is no longer driven by

the pulley shaft, or a poor pipe connection may leak all that the pump

delivers.

The amount of oil required by each lead or bearing should be carefully

determined by experiment, and kept constantly at the right number of

drops per minute.

The feed adjustments jar loose, and should be inspected frequently.

(121) Oil Cup Failure.

Oil cups should be cleaned out frequently with gasoline or kerosene, as

any gum or lint will interfere seriously with the feed. They should be

adjusted and filled frequently to prevent any possible chance of a hot

bearing.

Oil cups should be as large as possible in order that they may be left

for considerable periods without danger of a hot box.

Cold weather affects the oil feed to a considerable extent, especially

with small oil cups, and they should be kept as warm as possible. When

heavy oils are used a cold draft will stop the feed.

Oils may be made more fluid in cold weather by the addition of about ten

per cent of kerosene.

(122) Hot Bearings.

A hot bearing is almost a sure sign of insufficient oil, and the trouble

should be located and remedied immediately. Oil pumps stopping, clogged

oil pipes or holes, frozen oil, or oil leaks are common causes of hot

bearings.

Never allow an engine to run with a hot bearing for any length of time,

as the bearing or piston may seize tight and wreck the engine. Inspect

the journals frequently to see if they are above normal temperature. A

hot, binding bearing often causes the effect of an overload on the

engine, slowing it down, and increasing the governor and fuel feed, this

is followed in a short time by the bearing seizing.

(123) Cold Weather Lubrication.

It is by no means uncommon trouble in cold weather to find excessive

fluctuations in pressure as the engine speed and temperature of the oil

varies. Thus, if the pressure be set correctly with the engine running

fast, and when just started up, it will be found, after half-an-hour’s

running, that, with the engine turning slowly, the pressure is far too

low, owing to the oil having become thin. If the pressure be then reset,

it may be found on next starting up from cold that the gauge goes hard

over, and may very easily be burst if the engine is run fast.

The point is one to which many designers of engines pay far too little

attention, though the difficulty may be very easily gotten over. The

secret lies in having the by-pass outlet of most ample proportions, so

that the excess of oil, however thick, can get away quite easily. If

there is any throttling of the by-pass, back pressure must result with

consequent increase of the pressure at which the by-pass valve comes

into operation. In other words, the pressure of the main supply to the

bearings will be increased.

A writer to “The Motor,” London solved this problem in the following

manner:

“Originally, the by-passage was somewhat small, little larger than the

oil delivery pipe to the engine, which was about 3/16 inch bore, and the

result was that the pressure when starting with the oil cold rose to

about 25 pounds per square inch, and fell to about one pound per square

inch with the oil hot and the engine running slow. It was possible,

however, to bore out the by-pass passage and fit a larger pipe, about

three times the area of the main delivery pipe, with the result that the

oil, when cold, never rose above about 15 pounds per square inch,

however fast the engine run. When thoroughly heated, the normal running

pressure was about 6 pounds per square inch, falling to 2 pounds per

square inch with the engine only just turning over, which brings up the

question of the correct working pressure. This will vary very largely

with the design of the engine, but, broadly speaking, the higher the

pressure the better for the bearings. The limiting figure is determined

by the tendency of the engine to throw out oil at the end of crankshaft

bearings, and by the amount that gets past the piston rings. Obviously,

an engine with new, tight bearings and new piston rings will stand a

higher pressure without undue waste of oil or excess deposit in the

cylinder head than will an old engine with worn bearings and slack

rings. And, again, the question will be affected by the design of the

pistons. For instance, where the trunk of the piston is bored for

lightness, much more oil will get past the rings than in cases where a

‘solid’ trunk is employed. Roughly speaking, 8 to 15 pounds per square

inch is a good figure for a new, high-speed engine. An old and worn

engine, particularly if not of a high-speed type, may require no more

than 2 to 6 pounds per square inch.”

[Illustration:

Brookes Gasoline-Electric Generating Units for Operating Search

Lights. An Independent Unit is Used for Each Light.

]

The writer recently encountered a rather curious difficulty in

connection with obtaining a free by-pass. The return pipe from the

by-pass led into the case carrying the gearwheels of the camshaft and

magneto drive, and oil continually flooded out from the end of the

camshaft and other bearings. The waste and mess were sufficiently

serious to warrant investigation, and the cover plate over the gears was

accordingly taken off. It was then noticed that the oil delivered to the

gearwheel case had only two small holes by which to drain away to the

crankcase. The flow from the by-pass was beyond the proper capacity of

these holes, and so the whole gearwheel case became filled with oil

under considerable pressure, quite possibly 2 or 3 pounds per square

inch, and it was not surprising that oil exuded from the ends of the

bearing. A few extra limber-holes, if one may borrow a nautical

expression, were drilled through to the crankcase, and no further

trouble was experienced.

(124) Plug Oil Holes When Painting.

When the chassis of the car is repainted it is well to see that all

exposed oil holes are stuffed with waste to prevent them from being

choked. Failure to observe this precaution may result in the holes being

clogged with paint, which if not removed before the car is started, will

prevent oil reaching the bearings.

(125) Oiling the Magneto.

Never oil the circuit breaker or circuit breaker mechanism, unless for a

drop of sperm oil that may be applied to the cam roller by means of a

toothpick. If oil gets on the circuit breaker contact points, it will

cause them to spark badly, resulting in pitting or destruction of the

points. If the oil is occasionally applied to the cam roller or should

oil accumulate on breaker points, the breaker should be rinsed out with

gasoline to remove the surplus.

Pitted or carbonized contact points are capable of causing much trouble,

and gummy oil or dirt will develop this trouble quicker than any other

cause. Use only the best grade of thin sperm oil on the ball bearings.

In the course of time the circuit breaker contact points will wear or

burn, causing imperfect contact, and too great a separation between the

points. The contacts should be examined from time to time, and if rough

or pitted, should be dressed down to a flat even bearing by means of a

dead smooth file, and the distance readjusted. The contacts should not

bear on a corner or edge, but should bear evenly over their entire

surface to insure a maximum primary current and spark.

CHAPTER XI

COOLING SYSTEMS

The object of the cooling system is not to keep the cylinder cold, but

to prevent the heat of the successive explosions from heating the

cylinder walls to a degree that would vaporize the lubricating oil and

prevent satisfactory lubrication of the cylinder and piston. The hotter

the cylinder can be kept without interfering with the lubricating oil,

the higher will be the efficiency of the engine and the greater the

output of power.

To obtain the greatest power from an engine, the heat developed by the

combustion should be confined to the gas in order that the pressure and

expansion be at a maximum, it is evident that the pressure and power

will be reduced by over-cooling as the heat of the expanding gas will be

taken from the cylinder and transferred to the cooling medium. The

temperature of the cylinder, and therefore the efficiency of the engine

is determined principally by the vaporizing point of the lubricating

oil, and consequently the higher the grade of the oil, the higher the

allowable temperature of the cylinder.

If cold water from a hydrant or well be forced around the water jacket

rapidly, the power will be greatly reduced owing to the chilling effect

on the expanding gas. There is not much danger in keeping the cylinder

of an air cooled engine too cool, in fact the great difficulty with this

type of engine is to keep it cool enough to prevent an excessive loss of

lubricating oil.

The valves, particularly the exhaust valves, should be surrounded with

sufficient water to keep them cool as they are subjected to more heat

than any other part of the engine, and are liable to wrap or pit. The

water leaving the jacket of a gasoline engine should not exceed 160° F.,

as temperatures in excess of this amount cause deposits of lime scale.

When possible, a portion of the cooling water should be run into the

exhaust pipe immediately after it has completed its flow around the

valves and cylinders, as the water cools the gas so suddenly that the

exhaust to atmosphere is rendered almost noiseless, and the exhaust pipe

is kept much cooler and less liable to cause fire by coming into contact

with combustible objects.

On some engines the exhaust pipe is water jacketed for some distance to

prevent dirty rusty pipes in the vicinity of the engine mechanism and

also to prevent injury to the operator should he come into contact with

the pipe.

Small engines and medium size vertical engines usually have the water

jacket cast in one piece with the cylinder casting and others have a

separate head that is bolted to the cylinder.

In the latter type the water flows from the cylinder to the head through

ports or slots cut in the end of the cylinder water jacket that register

with similar slots in the jacket of the head.

Thus in this construction we have not only to pack the joint to prevent

leakage of gas from the cylinder, but also to prevent the leakage of

cooling water from the jacket into the cylinder, or outside. Thus there

is always a chance of water leaking into the cylinder bore and causing

trouble unless the packing is very carefully installed and looked after.

In large horizontal engines the gas and water joints are never made at

the same point, as it would be practically impossible to prevent leakage

into the cylinders of such engines.

When the cylinder and cylinder water jackets are cast in one piece

without a water joint at the junction of the cylinder and the head, the

water connection between the head and the cylinder being made by pipes

external to the castings.

Small, portable, stationary engines are sometimes “=HOPPER COOLED=,” or

cooled by means of the evaporation of the water contained in an open

water jacket that surrounds the cylinder.

The hopper is merely an extension of the water jacket such as used on

all water cooled engines, the only difference being that the top of the

hopper is open permitting the free escape of water vapor or steam to the

atmosphere. The water level should be carried within two inches from the

top of the hopper.

Water when converted into vapor or steam absorbs a great quantity of

heat, and of course the steam carries the heat of evaporization with it

when it escapes to the atmosphere.

As the hopper is open to the air, the temperature of the cylinder cannot

exceed 212° F. (temperature of boiling water) as long as there is

sufficient water left to cover the cylinder.

The hoppers contain sufficient water for runs of several hours’

duration, and as the water boils away or evaporates, it may be

replenished by simply pouring more water in the top of the hopper.

Hopper cooling is used principally for small portable engines where the

weight of a water tank or other cooling device would be objectionable

and also where there is danger of freezing the pipes and connections of

other systems.

The loss of water by evaporization is from .3 to .6 of a gallon per

horsepower hour; that is, for a 5 hp. engine the loss would be from 1.5

to 3 gals. for every hour that the engine was operated under full load.

The cylinder and the water jacket are cast in one integral piece, with

no joints of any kind in either the combustion chamber or in the water

jacket.

[Illustration:

Fig. 124. Air Cooled “Grey Eagle” Aeronautical Motor. Note the Depth

of Cooling Ribs.

]

A system of cooling by which the heat of the walls is radiated to the

air directly without the medium of water is often used on small high

speed engines, and is known as “=AIR COOLING=.”

This type of cylinder is surrounded with radiating ribs or spires which

increases the radiating surface of the cylinder to the extent that the

required amount of heat is lost to allow of economical lubrication. This

system is desirable where the weight of radiators and water would be a

drawback, where it would be inconvenient to obtain water, or where there

would be trouble from freezing. An air cooled motor generally is

provided with a fan that increases the efficiency of the radiating

surface by changing the air between the ribs. With aeronautical motors

such as the Gnome, and Gray Eagle, shown by Fig. 124, the circulation of

the air due to the propeller and the rush of the aeroplane is sufficient

to thoroughly cool the machine.

As a rule, the air cooled motor is made more efficient in fuel

consumption than the water cooled type because of the high temperature

of the cylinder walls. In fact all engines are air cooled eventually,

whether the heat is radiated at a high temperature by the fires, or at a

lower temperature through the circulating water and radiator.

When the engines are of the portable type, and likely to be used out of

convenient reach of water, the hopper or =EVAPORATOR TANK= system is

used, the tank system being used for the larger engines. In effect, the

tank system is the same as the hopper cooler, the heat being dissipated

principally by evaporation, although some heat is radiated from the

surface of the tank itself. The difference between the two systems is

merely one of size, the tank offering a greater area for the emission of

heat than the hopper.

A tank-cooled engine has one pipe running from the top of the cylinder

to a point near the top of the tank, the bottoms of the cylinder and

tank being connected together by another pipe.

When the water becomes heated in the cylinder, it expands and becomes

lighter than the cold water in the tank and consequently rises to the

surface of the water in the tank through the upper pipe. As the warm

water flows into the tank, it is immediately replaced by the heavier

cold water that flows into the cylinder from the bottom of the tank

through the lower pipe. This successive discharge of the heated water

from the cylinder to the tank sets up a continuous flow of water through

the water jacket of the cylinder, which transfers the excess heat of the

cylinder to the tank where it is dissipated to the atmosphere by

evaporation and radiation.

The circulation of the cooling water set up by the action of heat or the

expansion of the water is called Natural or Thermo Syphon circulation.

Cooling tanks may be used profitably with stationary engines if the tank

can be located so that vapor and steam produced will not be

objectionable. If the tank is used inside of a building, the vapor

should be conveyed to the outside air by means of a stack or chimney, or

by means of a small ventilating fan driven by the engine.

The water consumption of a cooling tank is from .3 to .6 gallons per

hour, the exact quantity varying with the atmospheric conditions and

temperature.

[Illustration:

Fig. 124-a. De Dion Bonton “V” Type, Air Cooled Aero Motor. The

Cooling Air is Furnished by a Blower Mounted on the Crank Shaft at

the Rear of the Motor. The Propeller is Driven from the Cam Shaft.

Courtesy of Aero.

]

For engines of from 10 to 50 horsepower a battery of cooling tanks may

be used, the number depending on the size of the engine. For natural

circulation, the tank should be installed so that bottom of the tank is

above the bottom of the cylinder for maximum results, if placed much

lower the engine should be provided with a circulating pump.

If water is used from the city mains from 10 to 15 gallons will be

required per horsepower hour, the exact quantity varies with the

temperature of the supply.

The water from very large stationary engines is cooled by allowing it to

trickle down through a cooling tower, which is built somewhat like the

screen cooler only on a larger scale. The object of the cooling tower is

to present the greatest possible surface of water to the air, this is

accomplished by screens or baffles that turn the water over and over as

it falls. The water, well cooled, finally collects in a cistern at the

base of the tower from which it is pumped back to the engine and thus is

used over and over again. This is an ideal system when water is

expensive and when engines of considerable power are used.

(126) Cooling System Troubles.

Overheating caused by deposits of scale or lime in the jacket is one of

the most common causes of an excessively hot cylinder. When hard water

containing much lime is heated, the lime is deposited as a solid on the

walls of the vessel forming a hard, dense, non-conducting sheet. When

scale is deposited on the outside of the cylinder walls it prevents the

transfer of the heat from the cylinder to the cooling water and

consequently is the cause of the cylinder overheating. Besides acting as

an insulator or heat, the deposit also causes trouble by obstructing the

pipes and water passages, diminishing the water supply and aggravating

the trouble.

Scale interferes with the action of the thermo syphon system more than

with a pump, as the pressure tending to circulate the water is much

lower. Whatever system is used, the scale should be removed as often as

possible, the number of removals depending, of course, on the “hardness”

of the water.

Large horizontal engines are usually provided with hand holes in the

jacket, through which access may be had to the interior surfaces on

which the scale collects. Under these conditions the scale may be

removed by means of a hammer and chisel.

The scale may be softened by emptying half the water from the jacket and

pouring in a quantity of kerosene oil, the inlet and outlet pipes being

stopped to prevent the escape of the oil. The engine should now be

started and run for a few minutes with the mixture of kerosene and water

in the jacket; no fresh water being admitted during this time. After the

mixture has become boiling hot, stop the engine and allow it to cool; it

will be found that the scale has softened to the consistency of mud, and

may easily be washed out of the jacket.

The work of removing the scale can be reduced to a minimum by filling

the jacket with a solution of 1 part of Sulphuric Acid and 10 parts of

water, allowing it to stand over night. The scale will be precipitated

to the bottom of the jacket in the form of a fine powder and may be

easily washed out in the morning.

If the jacket water is kept at a temperature above 185° F. the amount of

scale deposited will be nearly doubled over that deposited at 160° F.

Wash out sand and dirt occasionally, a strainer located in the pump line

will help to keep the jacket clear and free from foreign matter.

If a solution of carbonate of soda, or lye, and water are allowed to

stand in the cylinder over night, the deposit will be softened and the

work with the chisel will be made much easier.

If a radiator is used (automobile or aero engine) the deposit can be

removed with soda, never use acid, lye, or kerosene in a radiator or

with an engine with a sheet metal water jacket.

=Obstructions in Water Pipes.= Poor water circulation may be caused by

sand, particles of scale, etc., clogging the water pipes, or by the

deterioration of the inner walls of the rubber hose connections.

Sometimes a layer of the rubber, or fabric of the hose may loosen from

the rest and the ragged end may obstruct the passage.

A sharp bend in a rubber hose may result in a “kink” and entirely close

the opening.

The packing in a joint may swell, or a washer may not have the opening

cut large enough, either case will result in a poor circulation.

Sediment is particularly liable to collect or form in a pocket, pipe

elbow, or in the jacket opposite the pipe opening. Oil should be kept

off of rubber hose connections as it will cause them to deteriorate

rapidly, this may finally result in water circulation troubles. Rubber

pipe joints between the engine and the radiator or tanks are advisable

as they do not transmit the vibration of the engine, and hence reduce

the strain on the piping. A strainer should be provided in order to

reduce the amount of foreign material in the water.

=Radiators.= A clogged radiator will give the same results as a clogged

jacket with the exception that steam will issue from the radiator if the

circulation is not perfect.

If the radiator becomes warm over its entire surface it is evident that

the water is circulating, the temperature being a rough index of the

freedom of the water, or the interior condition of the surfaces. A

leaking radiator may be temporarily repaired with a piece of chewing

gum.

Should the radiator be hot and steaming at the top and remain cold at

the bottom for a time, it shows that the water is not circulating and

that the jackets on the cylinders are full of steam. Such a condition

usually is indicative of clogging between the bottom of the radiator and

pump, between the pump and bottom of cylinders, or of a defective pump.

[Illustration:

Natural Gas Plant at Independence, Kansas. Used for Pumping Gas From

the Wells to Various Distributing Points.

]

Thermo-syphon radiators are more susceptible to the effects of sediment

and clogging than those circulated by pumps.

A radiator may fail to cool an engine because of a slipping or broken

belt driving the fan, or on account of a loose pulley or defective belt

tension adjuster. Keep the belt tight. The fan may stick on account of

defective bearings.

Radiator may be =AIR BOUND=, due to pockets or bends in the piping

holding the air.

=Rotary Pump Defects.= A defective circulating pump will cause

overheating, as it will supply little if any water to the jackets.

Examine the clutch or coupling that drives the pump and see that the key

or pin that fastens it to the shaft is in place. Next see that the

driving pinion and gear are in mesh and properly keyed to their

respective shafts.

In some cases the shaft has been twisted off, or the coupling pin

sheared through by reason of the shaft rusting to the pump casing. Worn

gears or impellers =IN THE PUMP= reduce the output and cause heating, as

will a sheared driving pin in the impeller. Wear and bad impeller fits

reduce the capacity of the pump.

Scale or sediment collecting in the pump sometimes strips the pins or

impeller teeth. Note the condition of the gaskets or whether the pump

shaft is receiving the proper amount of grease. Put a strainer in pump

intake. See that no leak occurs on pump intake pipe.

To avoid the trouble and expense due to cracked water jackets, never

neglect to drain the cylinders and piping from all water in freezing

weather. Drain cocks should be provided at the lowest points in the

water circulating system for this purpose. It would be well to provide

an air cock at the highest point in the line in order that all of the

water can drain out as soon as the drain cock is opened.

With automobile or portable engines it is not always convenient or

possible to drain the engine every time that it is stopped and

consequently we must resort to a “non-freezing” mixture or at least a

solution that will not solidify under ordinary winter temperatures. Such

a solution should be chosen with care, as many will cause the corrosion

and destruction of the jackets and piping; =NEVER USE COMMON SALT= and

water under any conditions.

Wood alcohol and water in equal parts, is often used for automobiles,

but is rather expensive for portable engines having a comparatively

great amount of water in circulation.

Unless the circulating system is absolutely air tight, as it is when

radiators are used, alcohol will be lost by evaporation and must be

replaced frequently.

The most practical solution for the average engine used, is made up by

dissolving about five pounds of =CALCIUM CHLORIDE= in one gallon of

water. This mixture will stand a temperature of about 15° F below zero,

and if diluted to half the strength will not freeze above zero.

Use =CALCIUM CHLORIDE=, not ordinary Salt (Sodium Chloride).

CHAPTER XII

GOVERNORS AND VALVE GEAR

(127) Hit and Miss Governing.

When the speed of an engine is held constant for varying loads by

missing explosions on the light loads and increasing the number for

heavy loads, the governing system is said to be of the “hit and miss

type.” The mixture remains constant in quantity and quality in this type

of engine. A hit and miss governor allows only enough charges to be

fired to keep the speed constant.

When the load falls off, with a natural tendency on the part of the

engine to increase its speed, the governor cuts out the next explosion

by holding the exhaust valve open and the inlet closed, thus preventing

fresh mixture from being drawn into the cylinder. With an increase in

load, the governor allows the valves to follow their regular cycle with

the result that a greater or less number are fired in succession. Hit

and miss governing is very economical for only full charges of the most

perfect mixture are fired, and with short exhaust pipes the scavenging

is much better than with other forms of governing. The principal

difficulty with this system is that the regulation is not as perfect as

with some other types.

(128) The Throttling System.

Unlike the hit and miss system of governing, the throttling type of

governor allows the engine to take an explosion on every working stroke,

the speed being held constant by either regulating the quality or

quantity of the mixture, or both. Throttle governor permits of close

speed regulation as the impulses are more frequent and not so violent as

with the hit and miss system.

The governor acts directly on the throttle valve, and at no time is the

operating mechanism disengaged from the driving cam. The throttle

governor engine is particularly well adapted for driving dynamos, supply

electric light, as the uniform speed gives a smooth, steady light

without the objectionable flickering so likely with the hit and miss

engine. To obtain the best fuel economy with a throttling engine, it

should be run close to its rated capacity, as the poor and imperfect

mixture admitted at light loads considerably increases the fuel

consumption.

[Illustration:

Fig. 76-d. De La Vergne Governor.

]

Practically all motors of the variable speed type such as are used on

automobiles and motor boats are controlled manually by the throttle;

although marine motors are often fitted with governors to prevent racing

when the screw is lifted out of the water in a heavy sea.

(129) The Controlling Governor.

The governor proper depends upon centrifugal force for its action, and

generally consists of two weights which are pivoted at one end to a

rotating shaft driven by the engine. When these weights are rotated

rapidly the bottoms are thrown outwardly by the centrifugal force and

tend to assume a horizontal position. The faster the weights are

rotated, the greater will be the tendency for the bottoms of the weights

to come into the horizontal, and the greater will be the pressure

exerted by them on the controlling levers connected to the throttle. It

is evident that the centrifugal pull on the weights varies directly with

the speed of rotation and consequently with the speed of the engine. The

exact relation between the travel of the weights and the speed of the

engine is controlled by a spring that acts between arms cast on the

weights and the spindle. If a heavy spring is used, greater speed must

be attained to move the weights a given distance than with a weak

spring, as the centrifugal force must be greater.

[Illustration:

Fig. 124-d. Governor and Governor Mechanism of Fairbanks-Morse Type “R

E” Engine. The Fly-Balls, Springs, and Control Rods Are Shown on the

Governor Staff. The Upper End of the Bell Crank Goes to the

Throttle.

]

The throttle valve of the engine is connected by a rod to the governor

through a sliding collar in such a way that the movement of the governor

weights due to an =INCREASE= of speed partially closes the valve until

the speed of the engine is reduced. Should the speed of the engines

=DECREASE=, owing to a heavy load coming on, the spring will force the

balls to occupy a lower position which will increase the valve opening

until the engine again reaches the normal speed for which the tension of

the spring is adjusted.

Thus the speed of the engine is kept practically constant by the action

of the governor in opening and closing the throttle, which in turn,

varies the =QUANTITY= of mixture admitted to the cylinder. The =QUALITY=

of the mixture is varied by hand, in the engine by means of cocks in

both the air and gas pipes. The =GOVERNOR PROPER= is of practically the

same construction in the hit and miss engine, the difference of the two

types lying in the method of connecting it to the controlling system. In

one case (hit and miss) the governor controls the exhaust valve, and in

the other (throttling) it controls the quantity of gas admitted by the

throttle valve. The speed of the engine may be varied within certain

limits by a lever connected to the valve controlling rod.

(130) Types of Governors.

The types of governors used on the leading makes of engines will be

found described and illustrated in Chapter V which treats of each engine

in detail.

(131) Governor Troubles.

Hit and miss governor troubles may be due to the following defects:

=BINDING GOVERNOR COLLAR=, stuck with dirt or gummy oil, will cause the

engine to die under load, and overspeed on light load.

=INLET VALVE LOCK= may be worn in such a manner as to prevent the valve

from seating during the idle strokes and lose fuel, or cause

overspeeding.

=DETENT LEVER KNIFE EDGE= may be worn, or rounded off, so that the

exhaust valve is not held open for the idle stroke. This defect will

cause overspeeding.

=SPEED CHANGING LEVER= may work loose and cause the speed to vary

erratically.

=GOVERNOR WEIGHTS= may be stuck on pins with dirt or gummy oil causing

engine to overspeed.

=LOST MOTION IN GOVERNOR GEAR= such as loose pins and bushings, worn

rollers, or bearing surfaces will cause the speed to vary continuously.

=LOST MOTION= on portable engines will cause the engine to run normally

in one position, and overspeed in another.

=WEAK OR BROKEN SPRINGS ON GOVERNOR= will cause engine to lose speed or

die down altogether. Springs may be stiffened by pulling out the coils.

=DRY GOVERNOR BEARINGS= or joints will cause binding and cause governor

to act sluggishly. Use plenty of lubricant.

=WORN ROLLERS= may cause a speed variation. Keep the governor well

oiled, clean, and free from gum.

If the knife edges are allowed to slip over one another, much wear is

caused on the cams and if allowed to continue, sooner or later the

engine will run away. Springs will weaken with age and hard usage. With

belt driven governors see that the belt is tight and that the lacing is

in good condition for a slack belt may allow the engine to overspeed.

I advise that every purchaser of an agricultural motor read his

instruction book with care, that is, locate all oil holes and note the

action and purpose of every part. If in doubt as to any part of its use

write the manufacturer of the motor.

(132) Throttling Governor Troubles.

=STICKING GOVERNOR VALVE= will cause the engine to overspeed; remove the

gum and dirt.

=LOOSE PINS OR BUSHINGS=, or lost motion in any part of the governor

mechanism will cause irregular motion or running; be sure that the

bearings and joints are well oiled.

=STUCK PINS= will cause the engine to overspeed on light loads, and fall

down on the normal load, or cause racing.

=WEAK OR BROKEN SPRINGS= will cause the engine to lose speed or to lie

down altogether even on light loads.

=STIFF GOVERNOR SPRINGS= cause the engine to speed up.

=SLIDING COLLAR= stuck will cause racing or a fluctuation in the speed.

Keep the governor well oiled, clean, and free from gum.

The governing valve should be removed from its care frequently and

thoroughly cleaned with kerosene. Deposits of carbon and gummed oil at

this point are dangerous because of the likelihood of their causing

overspeeding.

(133) Valve Gear Arrangement.

The valve operating mechanism lay-out depends upon the cylinder and

valve arrangement, and consequently varies in detail with different

engines.

[Illustration:

Overhead Valve Arrangement of the Fairbanks-Morse “R E” Engine.

]

Fig. F-14–15 in Chapter V, shows the valve gear of an upright engine

having the inlet and the exhaust valves located in pockets placed at one

side of the cylinder. The inlet valve is operated by a valve rod that is

actuated by the cam. The exhaust valve stem is raised and lowered,

directly, through a cam on the same shaft. The method of driving the

valves in this engine is practically standard for all vertical engines

having the valves located in pockets. This system is used in a greater

proportion of automobile engines.

The opposed engine has the cylinders arranged on opposite side of the

crank case, and makes an exceedingly well balanced and quiet running

engine; as there is no point in the revolution where either the crank

throws or connecting rods have an unequal angularity, or differ in

velocity.

While this type of two cylinder engine is common in automobile practice,

it is not often met with in stationary work, the cam-box and the cam

being directly in the center of the crank case.

The opposed type of engine is particularly well adapted for aeroplane

service as a steady, quiet running engine is an absolute necessity

because of the frail construction of the aeroplane frame.

(134) Cam Shaft Speeds.

The valves of the gas engine are opened and closed by means of cams or

eccentrics, that are geared to the crankshaft, and which also control

the timing.

As a four stroke cycle engine performs all of the events, or a complete

cycle in two revolutions of the crankshaft, it is evident that the cam

must go through the routine in one revolution or must revolve at

=ONE-HALF OF THE CRANKSHAFT SPEED=.

Therefore the cam gear ratio must be as one is to two, the smaller gear

being placed on the crankshaft, the gears being known as the “half time

gears.”

As a two stroke cycle engine goes through the routine of events in every

revolution, the cam-shaft must run at crankshaft speed so that the cam

outline makes one revolution in the same time as the crank. The cam

shaft speeds given here apply to all engines of the corresponding cycle

no matter whether the valves are of the poppet, rotary or slide-sleeve

types.

(135) Valve Gear Troubles.

The valve gear mechanism causes trouble principally through the wear of

the various parts which results in a change in the valve timing, or in

the lift of the valves. Loss of power, =MISFIRING=, and overheating are

the result of such derangements.

Often trouble is caused in reassembling the valve mechanism after the

engine has been torn down for repairs, which trouble may generally be

traced to incorrect gear meshing.

The following list will give the principal defects due to the wear of

the valve mechanism.

(a) =WORN CAM GEARS= change timing because of play, or “back lash” in

the teeth, or cause a howling or grinding noise, that will cause the

owner to believe that the end of the engine is near. =MISFIRING= and

=LOSS= of power are probable results of a change in the timing. If any

of the teeth are stripped from the gear you may be sure that the timing

is changed. Replacement with a new gear is the only cure for a worn or

broken gear.

(b) =GEARS NOT IN PROPER MESH= due to an error in assembling the gears,

will prevent the engine from being started, or cause misfiring and loss

of power.

The maker of the engine generally marks the teeth that go together, but

if no such marks appear, the owner should center punch or scratch them

before taking down the engine.

to a loose set-screw will cause all of the troubles due to a change in

the timing. Examine the key carefully, for dirt often collects in the

key-way to such an extent that it is liable to be mistaken for the key.

Keys and pins have sheared in two, allowing the shaft to slip in the

gear.

(d) =WORN CAM-SHAFT BEARINGS= are the cause of trouble, as they will

change both the timing and the lift of the valves. If much play exists

in the bearing, it will prevent the valves from lifting at the proper

time, and will also reduce the lift by the amount of the play, which

sometimes has a considerable effect on the free passage of the gases. If

the cam-shaft bearings are of the bushing type they should be replaced

with new paying attention at the same time to the condition of the

shaft. If rough or shouldered the shaft should be machined to a dead

smooth surface. If on a large engine and of the adjustable type, the

shims should be removed as required or the wedges adjusted.

(e) =LOOSE CAMS OR ECCENTRICS= will change the timing because of lost or

sheared keys. If your cams are not integral with the shaft, look them

over occasionally and be sure that the keys are tight. Loose cams will

produce thumping and grinding and may often be located by the sound. See

that the key-way is not worn when fitting keys.

If the cams are fitted with taper pins it would be well to ream the hole

before placing new pins, as there is a liability of the hole being worn

oval.

(f) =A TWISTED OR SPRUNG CAM-SHAFT= will change the positions of the

cams relative to one another, and not only will change the time of all

cylinders, but will change their time relatively causing the engine to

run out of balance, or produce an unusual vibration.

(g) =WORN CAMS= are causes of a change of timing on all types of

engines, and are the most frequent cause of reduced valve lift with its

consequent trouble of overheating.

If the outline or contour of a cam is changed with wear it should be

replaced, if keyed to the shaft, as it will be a constant source of

trouble. If the cams and cam-shaft are in one integral piece, it will be

necessary to replace the entire shaft.

(h) =WORN CAM ROLLERS AND ROLLER PINS= will reduce the lift of the

valves, and in the case of a broken or sheared pin will prevent the

valve from lifting at all. Always replace loose pins or loose rattling

roller.

(i) =PUSH ROD DEFECTS.= Too much clearance between the push rod and

valve stem will reduce the lift of the valves and change the timing. The

clearance for small engines should be equal to the thickness of a

visiting card, and for large engines is somewhat larger, say 1–16″. The

increase of clearance is due principally to wear.

Too small a clearance should be avoided for the reason that the valve

stems expand with the heat and will lift the valves too soon, or even

permanently until readjusted. Broken valve springs will cause trouble,

or lost keys that retain the valve spring washers. Loose adjusting

screws on the push rods or stripped threads will delay the valve

opening.

(j) =TAPPET LEVER DEFECTS= are generally caused by wear or poor

adjustment. Loose pins or bushings, too much clearance between the

tappet and valve stem or broken valve springs, or loose adjusting screws

will produce changes in the timing or valve lift.

(k) =BENT VALVE ROD.= A bent valve rod will shorten the travel of the

valves, and change the timing.

(l) =CAM LEVER OR PIN= will cause timing troubles if the pin or bushing

are loose or worn, by reducing the travel of the valves.

When occasion arises for the removal of valves, the opportunity should

be taken to clean the stems and guides, which may be more or less gummed

with ancient oil. Freedom of valve movement is of extreme importance,

and for this reason neither the cleaning nor the lubrication of the

stems and guides should be neglected. The occasional use of a little

kerosene will prevent gummy accumulations, but care should be taken not

to allow the kerosene to wash out all of the oil and thereby leave the

surfaces dry.

A broken valve spring, though not a common occurrence, is not an unknown

possibility. If no spare spring is at hand, a plan that can be

recommended is to turn the broken spring end for end, thus bringing the

finished ends up together; this will prevent the spring from shortening

by overlapping, and winding itself together.

(136) Valve Timing.

The exact time at which the valves of a four stroke cycle engine open

and close depends to a great extent upon the speed of the engine, the

fuel used, the compression pressure, and the relation of the bore to the

stroke.

As these items vary in nearly every make of engine there has appeared in

the technical press, a great mass of seemingly conflicting data. Engine

speed is the principal factor in determining the timing.

Correct valve timing plays a considerable part in the output and

efficiency of an engine, for if the inlet valve, for example, opens too

late, the cylinder will not receive a full charge. If it opens too early

the hot gases in the cylinder will ignite the gas in the carburetor and

cause back-firing. Should the exhaust open too late, the retention of

the hot gas in the cylinder is likely to cause overheating.

The timing of the valves is usually expressed in degrees of the circle

described by the crank-pin, or the angle formed by the crank with the

center line of the cylinder at the time the valve is to open or close.

(137) Valve Setting on Stationary Engines.

The exhaust should open when the crank lacks 30° of completing the outer

end of the power stroke, that is, the crank should make an angle of 30°

with the center line of the cylinder when the exhaust valve begins to

open, and should be inclined =AWAY= from the cylinder. Some makers have

the exhaust open a little later in the stroke, but little is to be

gained with a later opening as the retention of the charge beyond 30°

heats the cylinder and does very little towards developing power. The

only advantage of the late opening is that the valve opens against a

lower pressure and causes slightly less wear on the parts.

The exhaust valve should close 5° =AFTER= the crank has passed the

=INNER= dead center on the exhaust or scavenging stroke, although some

makers close the valve exactly on the dead center. The 5° should be

given to allow the gas all possible chance of escape. The piston is said

to be on the inner dead center when it is in the cylinder as far as it

will go, and on the outer dead center when it is on the center nearest

the crankshaft.

The =INTAKE= valve should open about 5° =AFTER= the exhaust valve

closes, or 10° after the crank passes the inner dead center. The inlet

valve should =NEVER= open before the exhaust valve closes on a low speed

engine. The above timing is for engines running 150–600 R.P.M. The

automatic type of inlet valve, of course, cannot be timed, but attention

should be paid to the strength and tension of the spring and the

condition of the valve stem guides.

The inlet valve should close 10° =AFTER= the crank passes the outer dead

center in order that the cylinder be filled to the fullest possible

extent. If the valve closed exactly on the dead center a partial vacuum

will exist and the charge retained in the cylinder will be comparatively

small, but if the valve remains open past this point the air would have

time to completely fill the cylinder and develop the capacity of the

engine. The longer the inlet pipe, the longer the inlet valve opening.

(138) High Speed Engine Valve Timing.

The faster a motor turns, all other things being equal, the greater the

amount of advance necessary with the valves, as the higher the speed the

less the time required to fill or empty the cylinder. In a short stroke

high speed motor the exhaust should close and the intake open as early

as possible in order to admit the full charge. The exhaust should open

early to allow of the full escape of the gases, as the time allowed for

expulsion is extremely short when an engine runs 1,000 R.P.M. and the

back pressure is liable to be considerable.

The inlet valve of high speed engines should remain open for a

considerable period after the crank passes the outer dead center on the

suction stroke, owing to the inertia of the gases which tends to fill

the cylinder. Lengthening the period of opening of the inlet valve in

multiple cylinder engines produces better carbureting conditions and

reduces the variations of pressure in the manifold.

=EXHAUST VALVES.= The exhaust valve should begin to open 40° =BEFORE=

the crank reaches the =OUTER= dead center on the working stroke, and

should close 10° =AFTER= the crank has passed the inner dead center.

=INLET VALVES.= The inlet valve should open 15° =AFTER= the crank passes

the inner dead center on the suction stroke, and should close 35° after

the crank passes the outer dead center.

The inlet valve should never open before the exhaust valve closes,

although this is done on several types of high speed aeronautical

engines. The makers of these engines claim that this practice scavenges

the combustion chamber more thoroughly and makes the mixture more

effective owing to the inertia of the burnt gases forming a partial

vacuum in the combustion chamber. The writer has never been able to get

satisfactory results with this timing and doubts whether it can be

accomplished successfully.

In timing an engine great care should be taken to get the crank exactly

on the dead center.

(139) Timing Offset Cylinders.

The only difference in timing engines with offset cylinders and timing

those with the center line of the cylinder in direct line with the crank

shaft, is in the locating of the dead center. With no offset, the center

of the cylinder, the crank pin and the crank shaft are all in one direct

line when the engine is on the dead center.

With offset cylinders the crank pin lies to one side of the cylinder

center line when on the dead center, on either the inner, or the outer

center. To find the center on an offset engine proceed as follows:

Turn the engine over slowly until the crank-pin reaches either the

extreme top or bottom point of the crank circle, depending on which

center is to be determined, and then turn very slowly until the centers

of the piston-pin, crank-pin, and crank-shaft are in line. With the

average engine this will be found a difficult and tedious job, and it

will be well to mark the dead center on the flywheel or other convenient

point to prevent a repetition of the job. The quickest method of

accomplishing the feat is to remove the spark plug or relief cock to

gain access to the piston, and insert a rod or pointer in the opening

thus provided.

Draw the piston back a short distance from the end of the stroke with

the pointer resting on the head of the piston, and mark this position of

the piston both on the pointer, and on the flywheel, using some

stationary part of the engine as a reference point.

Now turn the crank over the center line until the piston is moving in

the opposite direction, and is the same distance from the end of the

stroke as shown by the mark on the pointer. Mark this position on the

flywheel using the same reference mark as before. We now have two marks

on the flywheel, and will bisect the distance between them, using the

dividing mark to obtain the center.

Place the bisection mark even with the reference point used for

obtaining the two previous marks on the flywheel, and the engine will be

on the true dead center, as the flywheel is now midway between two

points of equal stroke.

(140) Auxiliary Exhaust Ports.

To decrease the amount of hot gas and flame passing over the exhaust

valve some makers provide their engines with auxiliary exhaust ports,

which are similar to the exhaust ports used on two stroke cycle engines.

The auxiliary exhaust consists of a series of holes drilled or cored

through a rib on the cylinder wall, the holes being so situated that

they are covered by the piston until it is at the extreme end of its

outward stroke. The holes are not uncovered until the burning charge has

been expanded and cooled to the greatest extent possible in the

cylinder. As soon as the piston uncovers the ports the greater portion

of the dead gas escapes instantly to the atmosphere, carrying with them

the greater percentage of the heat and flame. The small amount of

residual gas that remains is forced out through the exhaust valve in the

usual manner, thus no flame ever reaches the exhaust valve.

The use of auxiliary exhaust ports produces a cooler cylinder as the gas

passes over the cylinder wall only once, and consequently is in contact

with the walls only one-half of the time usual with the ordinary system.

The cool cylinder lessens the liability of =PREIGNITION= and decreases

the consumption of cooling water and lubricating oil. Auxiliary exhaust

ports are particularly desirable on air cooled engines.

(141) Valves and Compression Leaks—Misfiring.

Owing to the intense heat in the cylinder, and the action of the gases

on the valves the seating surfaces become =ROUGH= and =PITTED= which

causes leakage and loss of compression. Exhaust valves cause the most

trouble in this respect as they are surrounded by the hot gases during

the exhaust stroke and are much hotter than the inlet valves.

To determine the value of the compression, turn the engine over slowly

by hand.

Leaking inlet valves usually are productive of =BACK FIRING= or

=EXPLOSIONS IN THE CARBURETOR= intake passages, or in the mixing valves,

as flame from the cylinder leaks through the valve and fires the fresh

gas in the intake.

=MISFIRING OR LOUD EXPLOSIONS= at the end of the =EXHAUST PIPE= are

indicative of leaky exhaust valves, if the mixture is correct and the

ignition system above suspicion. Misfiring caused by leaky exhaust

valves is due to combustible mixture escaping from the cylinder to the

exhaust pipe and being ignited by the succeeding exhaust of the engine.

If the engine has more than one cylinder, test one cylinder at a time,

opening the relief valves on the other cylinders. Now take a wrench and

=ROTATE= the inlet valve on its seat, for it may be that some particles

of carbon or dirt have been deposited on surface of the valve seat which

prevents the valve from closing properly. Rotating the valve will

usually dislodge the deposit.

Try the compression again; if there is no improvement, rotate the

exhaust valve on its seat in the same manner, and repeat the test for

compression. =ROTATING THE VALVES IN THIS MANNER WILL OFTEN MAKE THE

REMOVAL OF THE VALVES UNNECESSARY.= When the valves are closed the end

of the valve stem should =NOT= be in contact with the =PUSH ROD=, or cam

lever. Suitable =CLEARANCE= should be allowed between the end of the

valve stem and the operating mechanism when the valve is closed; this

clearance varies from the thickness of a visiting card on small engines

to ⅛ of an inch on the large. If the valve stem is continually in

contact with the push rod it cannot seat properly and consequently will

leak. Wear on the valve seats and regrinding reduces this clearance,

wear on the ends of valve stems and push rods from continuous thumping

increases it. Keep the clearance constant and equal to that when the

engine was new. On many engines this clearance is adjustable to allow

for wear by lock nuts on the ends of the valve stems or push rods.

Practical Hand Book of Gas, Oil and Steam Engines Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel. · 第 19 / 20 章

The Wico igniter produces a spark similar to that of the conventional