Presented at
Cleveland Section Meeting
October 20, 1916
STEAM MOTOR-VEHICLES
BY ABNER DOBLE*
* Vice-president, General Engineering Co.
(Detroit Section Associate)
The purpose of this paper is to present a summary of investigations
covering a period of nine years. These were made to determine
the possibility of overcoming certain serious objections and disadvantages
under which the steam motor-vehicle formerly labored.
Ten years ago steam cars were in their zenithnot that
a large number of makers were producing them, nor yet that the
majority of cars were steamers, but rather that a most progressive
and prosperous organization was producing these cars on a real
quantity basis. The White steamer of that day was universally
respected or beloved, accordingly as the person affected was a
gas-car man or a steamer advocate.
The Stanley steam car has been manufactured since 1898 without
cessation. The evolution of this car has been gradual and conservative,
and it has enjoyed a well-merited reputation for service at low
cost. A fire-tube boiler and locomotive-type engine have been
used from the first. Stanley Bros. have added improvements only
when there was a well recognized demand. They have thus accumulated
those necessities of modern motor cars, such as electric lights,
streamline bodies and one-man top. A condenser was adapted to
the car in 1914, and as a result about 200 miles can be covered
on one filling of the boiler. Kerosene is now burnt in the main
burner (with gasoline for starting and for the pilot), and the
mileage per gallon is high. The fusible plug has been abandoned
in favor of a thermostat for shutting off the fuel in case the
supply of water runs short.
A large number of more or less ineffective attempts have been
made to produce a satisfactory steam-car by persons ill-informed
on the actual requirements and apparently lacking in the necessary
understanding of automobile-production conditions.
Immediately after the early-day popularity of the steam-car
the internal-combustion engine began to be favored by engineers.
With the introduction of the long-stroke high-speed engine in
Europe the steam-car fell behind rapidly in the march of progress.
I do not wish to convey the impression that motor-vehicle builders
erred in selecting the gasoline engine. The market demanded cars
and more cars, and the makers chose the only practical powerplant
available. No one wanted a vehicle that emptied a horse-trough
every twenty miles. Very few drivers were equal to the task of
properly feeding the boiler. The idea of spending all the way
from a quarter of an hour to an hour and a half in starting soon
lost its relish.
LOW MILEAGE A DISADVANTAGE
One great disadvantage of the steam-car was the insufficient
mileage that was obtained from the water that could be conveniently
carried. Several steam-cars were equipped with an apparatus intended
to condense the steam, but a continuous run of 100 miles without
refilling was uncommon. Owing to the use of heavy cylinder-oil
these condensers as well as the water tank required periodical
cleaning. Steam cars not so equipped would run approximately 30
to 35 miles on a tank-full, about 35 to 40 gals.
Apparently no one had considered using a honeycomb radiator.
The reasons advanced against it were that the thick oil was liable
to clog the extremely small passages, and that the exhaust steam
(particularly in cars with flash boilers) was liable to melt the
solder. It was also believed that oil would injure the boiler,
cause violent foaming and that the successful lubrication of a
steam engine required a heavy molasses-like oil. It was particularly
hard to reconcile these beliefs, and we determined that the best
thing to do was to put a honeycomb radiator on a car and operate
it with a fire-tube boiler. This we succeeded in doing late in
1913, and obtained several startling results. The car would run
anywhere from 1000 to 1500 miles on one tank (24 gal.) of water.
The boiler operation was entirely unaffected by the oil pumped
into it from the engine cylinder. Having shown that it was possible
to travel an adequate distance on one supply of water, we turned
to the study of the steam-generator, with special regard to its
operation when fed with water containing oil, graphite, and in
winter, alcohol.
The so-called flash boiler, consisting of a series of coils
forming, in effect, one continuous tube, was naturally out of
the question. Its entire absence of steaming stability was a source
of constant aggravation to a driver in a hilly country. However,
it had the immense advantage that the direction of the water-flow
was opposite to the flow of the gases of combustion, which allowed
the water to take the last possible heat unit from the flue gases.
Its all-steel construction with consequent immunity from leaks
due to low water was also a great advantage.
The vertical fire-tube boiler was also out of the question
for production on account of its great weight, potential danger
present with a large diameter shell, its high cost because of
the apparent necessity of winding the shell with a mile of piano
wire and its liability to leaks both from oil working through
the expanded joints where the tubes were fastened into the heads
and from overheating with low water. Notwithstanding these formidable
disadvantages, when in good condition it was the best boiler from
the driver's standpoint, owing to its large reserve of water heated
to the steam temperature, which admitted of great acceleration.
It was also efficient because of the surface-heating arrangement
with extremely short distance through which the gases radiated
heat to the tubes.
The water-tube boiler, which has been built in almost every
conceivable shape for motor-vehicle service, seemed to offer a
basis on which the good characteristics of the flash and water-level
types of boilers might be combined. This at first seemed a forlorn
hope, as the apparently conflicting conditions seemed unreconcilable.
Deposits of scale occur in every type of boiler, with a resultant
drop in efficiency and added liability of burning the already
extremely hot heating-surface. In the water-level types this scale
would settle in the non-circulating portions of the boiler, such
as the water-column and blow-off connections.
STEAM-GENERATOR REQUIREMENTS
In studying these apparent conflicts, we could see that all
functions were closely related. That is, a water-level boiler
held the temperature of the steam practically constant, with no
possibility of temperatures high enough to effect a deleterious
change in the lubricating oil. This allowed the same oil to be
used over and over. It also allowed the use of a soldered radiator
to condense the exhaust steam. The honeycomb radiator condenses
such a large portion of the exhaust steam, that little make-up
water is required, with the result that much less scale is introduced
into the system. Since little water is lost, in winter, alcohol
can readily be used in large enough proportions to prevent freezing.
The use of a mixture of alcohol and water results in an imperceptible
drop in power because of the large amount of heat-carrying medium
that must be circulated.
The use of regular gasoline-engine cylinder-oil for the lubrication
of those parts in contact with the steam, would make a steam generating
and condensing system of this kind practical. Such oil is more
agreeable to handle and easier to procure than the heavy oil used
in steam engines. It rapidly forms an emulsion with the water,
owing to the violent agitation and intimate contact. It cannot
form clots and clog up the radiator passages, and since the return
from the radiator is introduced into the bottom of the water-tank
the agitation of the contents of the tank is sufficient to maintain
the emulsion. This insures that the oil is regularly pumped into
the boiler along with the water. The oil that thus finds its way
into the boiler performs several valuable functions: First, it
coats thoroughly every portion of the interior of the boiler with
an exceedingly thin film of oil. While this is thin at ordinary
temperatures, it is much thinner at 485 deg. F., which is the
approximate temperature of the boiler at 600 lb. pressure.
Scale will not stick to a surface coated with oil, so that
the interior of the boiler is absolutely protected from scale
as well as from rust. Very little scale-bearing water is introduced
into the system because of the efficient condenser, but in several
years' operation enough scale would be formed to render a boiler
useless, even though none of it adhered to the tubes. The second
function of the oil in the water is to combat this condition,
which it does with thoroughness and dispatch. As soon as a particle
of scale is thrown out of solution it is thoroughly coated with
oil, which renders it incapable of sticking to any other particle.
This scale therefore remains in suspension, and owing to the violent
ebullition and constant flow toward the steam outlet is carried
along and out with the steam, finally reaching the water-tank.
This action appears to be exceedingly thorough, and in several
years' use no accumulation of scale can be detected in any portion
of the boiler. It appears that the scale problem can be solved
when such particles of foreign matter are kept small enough so
that they will be readily carried over with the steam.
The steam generator, Fig 1, which
has been worked out to fulfill these interrelated conditions,
is a flash-generator in theory, yet has the appearance of a water-tube
boiler and has a water-level in the evaporating zone. The close
and regular heating-surfaces give heat-transfer conditions resembling
those of a fire-tube boiler, and yet the progressive water-flow,
counter to the flow of the gases, with no circulatory flow, is
characteristic of the flash type. The water enters the bottom
of an economizer-zone and flows to the top under the action of
the pumps and gravity; the hottest water collects at the top.
From there the water overflows through a connecting pipe into
an evaporating zone, where it is converted into steam. The water-level
is maintained about half-way up the generator by an automatic
by-pass valve; this is so arranged that when the regulator tube
is filled with steam the by-pass valve is closed by the expansion
of the tube, forcing the water from the pumps to lift the check-valve.
The water can then enter the generator. As the water-level rises,
the regulator tube is filled with water from an exposed pipe leading
from the water manifold. This water is not in circulation in the
generator, and therefore remains quite cool. The regulator tube
then contracts and opens the by-pass valve, allowing the water
to return to the tank.
The generator tubes are vertical, swaged at the ends to half
their diameter, and welded into horizontal headers, top and bottom.
Each section thus formed is connected to manifolds, top and bottom,
for the exit of steam and the entrance of water. This construction
is absolutely without danger of explosion and is also cheap to
manufacture. Any damaged section can be replaced, or isolated
pending replacement, in a few minutes. The casing of this generator
consists of a ½-in. asbestos board, ¼-in. of mineral
wool and a planished-iron jacket.
STARTING STEAM CARS
Perhaps the greatest disadvantage in operating steam-cars was
that known as "firing-up," or getting the burner started
to raise steam. Steam-cars almost without exception have used
a Bunsen burner of the vaporizing type, which required pre-heating
to vaporize the fuel. This was necessary to insure that enough
mixture passed into the combustion space to ignite readily and
to continue burning. After combustion was well under way the fire
kept the vaporizer heated. When standing, a supplementary burner
was lighted to maintain the vaporizer heat; this ignited the main
burner when the car was to be used again.
About three years ago we first tried to eliminate the time
and labor required to start combustion. It was suggested that
a carbureter and spark-plug be useda blower driven by an
electric motor to furnish the requisite air, the idea being to
use these with a regular Bunsen burner. This was found to work
fairly well with gasoline, except that undesirable precipitation
of the fuel took place. It also seemed necessary to provide means
by which kerosene could be used for starting, without recourse
to gasoline.
We finally discovered that kerosene could be ignited by an
electric-spark with absolute certainty and regularity, if these
conditions are observed: First, the kerosene must be separated
mechanically, so that the individual particles are sufficiently
small to insure a rise in temperature past the point of ignition
during the time in which they absorb heat from the spark; second,
the spark must occur near the atomizing nozzle, at which point
the fog is so dense that one group of kerosene particles igniting,
invariably ignite the rest. Third, the velocity must be so low
that the particles can absorb sufficient heat from the spark to
exceed the ignition temperature. Fourth, the mixture must be much
richer at the point where ignition is to occur than is that for
most efficient combustion. The combustion should occur in a refractory
chamber so arranged that it attains an extremely high temperature;
complete combustion of a large amount of fuel can then be obtained
in a small space.
Thus, in a complete apparatus we have an electric motor, direct-connected
to a multivane blower, and a graduated kerosene pump. The kerosene
pump draws a measured quantity of fuel from the supply tank and
forces it through the atomizing nozzle; the resultant fog is ignited
by a spark-plug. A measured amount of air is forced in by the
multivane blower, which whirls the rich ignited mixture down through
an inlet tube against the bottom of the refractory combustion
chamber, where the fuel is consumed. To stop the combustion it
is only necessary to break the blower-motor circuit. This is done
automatically by a regulator set to operate at a pre-determined
steam pressure.
With the old-fashioned Bunsen burner, which has been used on
all previous steam-cars, it is necessary first to heat the vaporizer.
This is done with a drip-cup or a painter's blow torch, although
on modern steam-cars acetylene gas is used. The fuel valve is
then opened slightly, allowing very little fuel to flow until
the burner has become well heated, after which the fuel valve
can be left open. The starting of the fire takes about six minutes
and requires the care of the operator until it is going well.
After the fire is started, steam is made quickly. On some types
of boilers enough pressure can be raised to start the car in about
a minute and a half after the fire is under way. It is therefore
apparent that if practically the entire time formerly used in
starting the fire can be saved, it is a reasonably simple matter
to build a powerplant that can be started in a short time, with
no labor or attention required.
The engine of a steam vehicle should
last for many years of hard service. It has proved to be a relatively
simple matter to provide ample dimensions of the working parts
so that the mechanism is safe for continued operation under maximum
conditions of load. In order to have efficient working it is necessary
to provide for high expansion. This can be obtained with a compound
engine, but not satisfactorily, as the ratio of cylinder volumes
has to be carefully determined in relation to the probable loads,
speeds and steam-chest pressures. These conditions vary so widely
that the single expansion engine, Fig. 2, is necessary.
To provide the high expansion desirable, with a simple noiseless
valve gear and one valve per cylinder, it is imperative to use
the uniflow principle. In the uniflow engine the valve takes care
of the steam inlet only, the exhaust passing out through ports
at the end of the stroke when these are uncovered by the piston.
It is thus possible to secure cut-off at 5 per cent of the stroke.
Since the thermal conditions in the uniflow cylinder are practically
ideal, it is unnecessary to use superheated steam. This means
that little cylinder lubrication is required, and the troubles
formerly caused by superheated steam are absent.
The engine directly geared to the axle, with a 47 to 48 ratio,
can produce enough torque to slip the driving wheels on dry ground.
The slow engine speed thus possible makes elaborate lubrication
systems superfluous. The general arrangement of the principal
parts of a steam-car is shown in Fig. 3.
ADVANTAGES OF A PERFECTED STEAM POWERPLANT
1. Torque range of 100 per cent with a maximum torque available
at zero speed; change-gear mechanisms and clutch therefore unnecessary.
Mean effective pressure (and equivalent drawbar pull) always under
control of the operator; variable by throttle from zero to maximum,
a maximum limited only by the resistance between the driving wheels
and road.
2. Utmost mechanical simplicity, with not over twenty-five
moving parts in the entire car, and only fifteen in the engine.
3. Smooth and quiet operation, owing to low engine speed and
to location of engine on axle.
4. Low running cost; kerosene or crude oil used for fuel.
5. Low manufacturing cost owing to simplicity of construction
and lack of fussy work in production.
6. Entire absence of lubrication troubles; no contamination
of crankcase oil by kerosene, gasoline, water, road-dust and carbon.
DISCUSSION
E. G. THOMAS:This paper recalls a conversation with Mr.
Doble, in which he contended that multicylinder engines are unnecessary
when if steam is used a two-cylinder engine is sufficient. We
then rode in his car at speeds varying from 1 to 60 m.p.h. It
was a most pleasing sensation. There was absolutely no noise.
The car attained any speed desired at any time.
MR. UTICH :What does the seven-passenger car weigh?
ABNER DOBLE:A seven-passenger car of 128-in. wheelbase,
56-in. tread front, 57-in. tread rear, equipped with a rather
heavy body and 33 by 5-in. wheels weighs 3100 lb., with tank filled
ready for the road.
CHAIRMAN ARTHUR J. SCAIFE:What is the greatest horsepower
obtainable with this type of powerplant?
ABNER DOBLE:The highest normal horsepower that we have
used so far is 25, but a 25 hp. steam powerplant at the standard
pressure of 600 lb. per sq. in. will exert about 132 hp. for about
eight minutes.
S. L. BLACKBURN:What is the maximum pressure capacity
of the boiler?
ABNER DOBLE:The boiler is designed for a working pressure
of 600 lb. The safety valve is set for 1000 lb. The boilers are
all tested to 5000 lb. They will rupture at about 8500 to 9000
lb. At this pressure the tubing ruptures at a place remote from
the welds. My own car has been in service since December, 1913.
The safety valve has never blown. This means that the maximum
pressure has never reached 1000 lb.
THERMAL EFFICIENCY
WALTER C. BAKER:Why is an efficiency twice that of a
gasoline car claimed?
ABNER DOBLE:Everything depends upon what you mean by
"efficiency." We know that 18 per cent thermal efficiency
is obtainable from a gasoline engine running at full load. We
also know that cars do not run at full rated load much more than
1 per cent of the time. .When running at 20 or 25 m.p.h. about
5 hp. is required to drive the car. Under such light load the
ordinary engine will have a thermal efficiency of about 4.5 to
5.0 per cent. The highest thermal efficiency we know of to-day
with the steam powerplant is about 21.8 per cent at its full rated
load. This is obtained by using a combustion system in which the
air is preheated, at the risk of burning out the grate bars. The
Doble steam generator has no grate bars, but uses a refractory
material that we developed. It will stand about 3400 deg. F. before
it fuses. The temperature attained in our fire box is about 2600
deg. F. The air is preheated to 200 deg. before it enters the
carbureter, by utilizing about one-third the heat that would otherwise
go out of the stack. The boiler efficiency without the economizer
is about 82 per cent. This is equivalent to standard practice
in boilers. With our boiler we can increase the efficiency about
4 per cent by the economizer and by using a regenerator, which
can be placed on the end of the stack, we can raise the boiler
efficiency to about 92 per cent. The best net thermal efficiency
that we have been able to secure from our powerplant is about
16 per cent under full load. With the 5 hp. load imposed when
a car is driven at 25 m.p.h., we realize 14 per cent net thermal
efficiency. My car, which was built three years ago, and is crude
in some ways, has been driven almost 40,000 miles. It will run
15 miles to the gallon of kerosene under favorable conditions,
and will average about 11.5 miles per gallon, although I drive
through traffic and mud a part of the time. The old type of steam
car never ran more than 7 miles per gallon.
H. H. NEWSOM :What piston speed is used in the engine?
ABNER DOBLE:We have found that the most efficient piston
speed is 375 ft. per min., which corresponds to a car speed of
about 37 m.p.h. 1 have driven my car 80 m.p.h. The corresponding
piston speed is 800 ft. per min., not counting the slip, which
would be about 12 per cent at that point, making a maximum piston
speed of about 900 ft. per min. I have never run an engine at
any higher speed than that in a car.
H. H. NEWSOM :What is the temperature of the steam?
ABNER DOBLE:The theoretical temperature of saturated
steam corresponding to a pressure of 600 lb. is 490 deg. F., but
we find sometimes that on ordinary loads, there will be 100 deg.
superheat in excess of that. Under full loads it will be down
to 490 deg. F., owing to the fact that we will then probably have
3 to 5 per cent of moisture in the steam.
TYPE OF COMBUSTION SYSTEM
MR. WAITE:What sort of a combustion system is used?
ABNER DOBLE:An efficient blower furnishes the requisite
amount of air, and mixes with it enough kerosene to make a very
rich vapor. The kerosene is atomized and the vapor ignited by
an electric spark before the air required for complete combustion
is added. The spark-plug is connected in parallel with the blower-motor
circuit. The ignited mixture flows through the inlet tube and
into the combustion chamber, where it burns completely before
the hot products of combustion pass through the boiler.
MR. SCHWARTZENBERG:What about the fire hazard?
ABNER DOBLE:It is negligible with kerosene as fuel.
WALTER C. BAKER:Is the exhaust clean when using kerosene?
ABNER DOBLE:Yes. All carbon is. consumed at 1800 deg.
F. The combustionchamber temperature under normal working conditions
is about 2450 deg. The feed is set so that the fuel is entirely
consumed. The exhaust will smoke sometimes in starting, until
a temperature of 1800 deg. F. is reached in the combustion chamber.
MR. SCHWARTZENBERG:Is the heat objectionable when driving
in summer weather?
ABNER DOBLE:The generator is insulated with a special
material that does not reach a temperature of much over 150 deg.
F. We use a dashboard that comes down to the frame, and then the
frame is covered with a floor. A space of 2 in. is allowed between
that floor and the floor-boards proper. We use a 1-in. cocoa mat
on top of the floor-boards. The result is a much cooler car than
one of the regular gasoline type.
CHAIRMAN ARTHUR J. SCAIFE:How flexible is the powerplant?
If the throttle is opened or closed suddenly, what is the variation
in pressure?
ABNER DOBLE:If the throttle valve is suddenly opened
wide with the car at a standstill, the pressure will drop from
600 to 450 lb. by the time the car reaches a speed of 60 m.p.h.
WALTER C. BAKER:How many seconds does it take to start?
ABNER DOBLE:Five and one-half seconds from a standstill
to 30 m.p.h.
E. L. CLARK:Fig. 3 shows the engine built right onto
the back axle. What is the unsprung . weight?
ABNER DOBLE:The unsprung weight added to the axle on
the older car was 100 lb. The new engine will add about 10 lb.
more, but we have saved about 15 lb. in the differential, as we
use no differential cage. The piston, piston-rod and cross-head
weigh about 8 lb. on each side of the engine. The latter runs
at 600 r.p.m. when the car is traveling 60 m.p.h.
Over 200 steam-driven omnibuses have been running for a long
time in England. Last year they changed the fuel from kerosene
to coke. The latter is fed by automatic stokers driven from the
engine. The grate rocks so many times a mile, and all the driver
has to do is shove in a little more coke every 10 miles or so.
Coke sufficient for about 50 miles is carried. They also use coke-burning
steam lorries.
A. M. DEAN:What is the temperature of the engine when
running at 25 or 30 m.p.h.?
A13NER DOBLE:The steam temperature at the intake when
running at 25 m.p.h. is just about 390 deg. F. The temperature
at the exhaust, in every case, is 212 deg. F., or within 2 or
3 deg. of that, because at the exhaust the steam contains about
15 per cent water.
S. L. BLACKBURN:What is the piston displacement of the
engine?
ABNER DOBLE:It is 314 cu. in. per revolution.
MR. DUNKIN:What is the bore and stroke of the engine?
ABNER DOBLE:It has a 5-in. bore and 4-in. stroke.
REVERSING ENGINE
E. L. CLARK:How is the engine reversed?
ABNER DOBLE:The "Joy" valve gear used was invented
a long time ago by David Joy in England. It is the same gear that
the White company used on its engines. The engine is reversed
simply by changing the timing of the valve; that is accomplished
by tipping the rock shaft to an inclination opposite to that used
in running forward.
H. H. NEWSOM:Does the Joy valve gear have a link motion?
ABNER DOBLE:No, it does not. It is called a radial valve-gear,
and is driven from the connecting-rod, as shown in Fig. 2. The
end of the anchor link is nearly horizontal. The valve link is
attached to what we call the "correcting" link, because
without it the valve would not have a correct motion.
H. H. NEWSOM:Is the control manually operated?
ABNER DOBLE:The control is by a pedal.
H. H. NEWSOM:Is it advanced as the speed increases?
ABNER DOBLE:No; to start the car the pedal is moved to
the first notch. That gives cut-off at three-quarter stroke. At
higher speed, fuel can be saved by moving the pedal to the next
notch.
W. D. APPEL:What is the maximum cut-off when the valve
gear is in the extreme position?
ABNER DOBLE:The maximum cut-off is 21/2 in. on a 4-in.
stroke. There are two other positions; the first for ordinary
running and for extreme acceleration is one-quarter stroke, and
the second for economical running, or for extremely high speed
after acceleration has cut-off at one-eighth stroke.
W. D. APPEL:With the cut-off set at one-eighth stroke,
would it be possible for the engine to stop an dead center so
that it could not be readily started?
ABNER DOBLE:Unless the cut-off is later than mid-stroke,
this can occur. In order to start under this condition, it is
necessary to use the reverse pedal first.
PRODUCTION COSTS
MR. SCHWARTZENBERG:With a properly equipped plant, turning
out three hundred cars a day, and with metal at normal prices,
what would be the cost of manufacture as compared to a $2,000
gas car?
ABNER DOBLE:A car to give the same power performance
as a Cadillac, for example, and with the same finish and quality
of workmanship, will cost $198 less per car. In general, the saving
will amount to 8 or 10 per cent of the list price of the car.
S. L. BLACKBURN:Can the car be built in any class? Say
for example in the $700 class?
ABNER DOBLE:Yes. But the performance will be better and
less care is necessary in finishing and fitting pistons and cylinders.
C. E. WILSON:Are the braking possibilities the same as
in gasoline cars?
ABNER DOBLE:Yes; by using the reverse pedal, it is possible
to stop almost instantly. Beside this, two sets of brakes are
provided as required by law. The center of gravity of the car
is low and nearer the rear than in gasoline cars, hence the car
holds the road better and the wheels do not slide so much 'as
they would otherwise. This makes the braking action more effective.
CHAIRMAN ARTHUR J. SCAIFE:How is the engine lubricated?
ABNER DOBLE:By the time the steam enters the cylinders,
it contains about 3 per cent moisture, which increases to about
8 per cent as the expansion takes place. This moisture does the
lubricating. Little internal lubrication is required, for the
piston speed is low at ordinary driving speeds. The cylinder surface
is cast iron, which is easy to lubricate. We use oil to prevent
corrosion and to help lubrication. The last gallon of oil I used
in my car was sufficient for 12,200 miles operation. The oil used
is primarily to clean the scale from the boiler.
GEORGE W. SMITH:What is the weight of the powerplant?
ABNER DOBLE:The new engine will weigh about 240 lb. The
old engine weighed 220 lb. The generator will weigh about 520
lb.; the water tank about 250 lb. The radiator will weigh 15 lb.
more than a gasoline-car radiator. The engine will develop 70
hp. continuously.
H. H. NEWSOM :Locomotives have traveled 50,000 miles
without any oil in the cylinder. Cast iron will get along with
little or no lubrication.
E. L. CLARK:Is there any possibility of knocking off
the cylinder head because of water in the cylinder when starting?
ABNER DOBLE:We use ordinary slide valves, placed under
the cylinders. Water that condenses in the cylinder drains into
the steam chest, because the valves fall away from their seats.
The car can stand for days and the throttle then be opened suddenly
without injuring the engine.
E. H. SHERBONDY:How is the water from the condenser handled?
Do you carry it back to the main supply tank and then into the
boiler?
ABNER DOBLE:The water from the condenser goes through
a pipe into the bottom of the water tank. From there it is forced
into the boiler by the boiler feed pump.
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