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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 offthe 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

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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 atank-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 wasopposite 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 waterheated to the steam temperature, which admitted of great acceleration. It was also

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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 severalyears' 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 regularheating-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

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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 ofwater. 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 -in.

asbestos board, -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 duringthe 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 amultivane blower, and a graduated kerosene pump. The kerosene pump draws a

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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 tooperate 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 entiretime 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 theworking parts so that the mechanism is safe for continued operation under

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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 thuspossible 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

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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 enginerunning 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 apart 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?

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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 completecombustion 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 notreach 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 aspeed of 60 m.p.h.

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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. Cokesufficient 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?

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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.

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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 wouldotherwise. 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.