Medical Society of the State of North Carolina. An.

Cyclopedia of automobile engineering; a general reference work on the construction, operation, and care of gasoline, steam, and electric automobiles, instruction in driving, commercial vehicles, motorcycles, motor boats aerial vehicles, self-propelled railway cars, etc online

. (page 22 of 27)
Online LibraryMedical Society of the State of North Carolina. AnCyclopedia of automobile engineering; a general reference work on the construction, operation, and care of gasoline, steam, and electric automobiles, instruction in driving, commercial vehicles, motorcycles, motor boats aerial vehicles, self-propelled railway cars, etc → online text (page 22 of 27)
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adapt the engine to the new fuel, this excess can be increased to fully
20 per cent. Different designs of gasoline and kerosene engines are
not equally well adapted for burning alcohol, though all will do so
with a fair degree of success.

The storage of alcohol and its use in the motor is attended with
much less danger than that of gasoline, and the exhaust from the
alcohol motor is not as apt to be quite so offensive as that from a
gasoline motor, though an excess of lubricant and imperfect com-
bustion will create an odor when the engine is not properly handled.
This is now an important factor in city traflBc, as pointed out in con-
nection with taxicab operation, and is daily becoming more so as the
number of vehicles increases.

No more skill is required to operate an alcohol motor than one
designed to run on gasoline, and the combustion chamber of the former
does not show the same tendency to soot up, nor does it, with proper
operation, show any effects of corrosion. By reason of greater clean-



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186 COMMERCIAL VEHICLES

liness in handling the fuel, increased safety of storage, and less
offensiveness in the exhaust, alcohol engines will sooner or later begin
to displace the gasoline motor, particularly when the production of
alcohol reaches a scale where its use will be on practically the same
economic le\'el. It has been thought that in this field, it would be
impossible to conveniently increase the compression of the motor
because of starting difficulties, but as the compression release employed
for starting on many gasoline motors is equally applicable to the
alcohol motor, this should not prove a deterrent.

In many localities, it is unlikely that alcohol power will be cheaper,
or as cheap as gasoline power for some time to come, but in isolated
districts such as those to which the motor road train is particularly
adaptable, the possibility of distilling the alcohol fuel right on
the ground would be a decided advantage, both practically and
economically. The raw materials ordinarily employed for this pur-
pose are sugar-mill waste (whether cane or beet), cornstalks, any
vegetable refuse or similar materials of a very inexpensive nature,
it having been demonstrated that it is possible to distill aclohol on
a commercial scale from the pine sawdust of the southern lumber
mills.

Producer Qas. So far, only the possibilities of employing a form
of liquid fuel have been considered, owing to its high value for the
purpose per unit of volume, as well as the ease with which it may be
stored and carried on the vehicle. Lack of these advantages would
appear to make the employment of any form of solid fuel out of the
question on an automobile. In fact, coal or coke, as a substitute for
alcohol, gasoline, or similar liquid fuels would hardly appear to
promise much for the commercial vehicle, whether from the stand-
point of economy or convenience. Experience with stationary plants
of all sizes has conclusively demonstrated, however, that these two
fuels when converted into a combustible gas and used in the internal-
combustion engine, are far more economical than any liquid fuel,
no matter how cheap, or than the same weight of fuel burned under
a boiler and converted into power through the medium of the most
advanced type of steam engine.

Hitherto, the size and weight of the necessary apparatus for
converting the solid fuel into the gaseous state has rendered its adapta-
tion to the automobile impractical. Four years ago, however, the



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COMMERCIAL VEHICLES 187

problem appeared to have been very satisfactorily solved in Great
Britain by the design of a gas-producer which was brought down to
such a degree of compactness as to make the entire plant quite suit-
able for installation in a commercial vehicle of the medium and heavy
types. The modifications necessary to adapt such a plant to the
confined space, as well as the arrangements required to render its
operation easy, will be plain from the description*.

Of course, none of the essentials, such as the fuel hopper, air
blower, water-feed pump, gas cooler, washer, and water tank have
been omitted. The plant is as complete as any used in the largest
stationary installations and the method of operation is the same.
As employed in the service in question, the producer was installed
on a double-decked omnibus equipped with a 40-horse-power, six-
cylinder, vertical, four-cycle motor, identical in all respects with
those employed with gasoline as fuel, except that the carbureter had
been removed and the inlet manifold connected directly with the
gas bag attached to the outlet of the producer. The latter is mounted
directly in front of the dash of the car and is so compact in design
as not to add greatly to its length. The producer conrfsts of a com-
paratively light malleable-iron casting while the supply of fuel b
carried in a sheet-metal tank, or hopper, fitted with large handholes,
or openings for rapid refilling with coal or coke.

The producer is fitted with a special grate bottom, an ashpan,
and cleaning cover, and above the grate on the side of the producer
body, a breach is fitted with a large lid for the purpose of cleaning and
lighting the fire. The top of the producer is open to the fuel hopper,
the fuel feeding automatically from the latter by gravity as fast as it
is consumed. An outlet for the gas in the form of a vertical tube
passes up through the bottom, terminating near the top, while an
open end is provided, surrounding which is a pendant tube of large
diameter, fixed to the top of the inner side of the hopper, this tube
being perforated at its lower end. To maintain the draught of air
necessary, a small centrifugal blower is installed and arranged to
be driven directly from the motor through a ratchet device similar
to that used on the starting handle of a gasoline motor, thus permitting
it to be rotated by hand when the motor is not running. A similar
device is also used on this crank handle, so that when the motor is
running, the handle is idle.



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188 COMMERCIAL VEfflCLES

In this producer, air is conveyed from the blower to the under side
of the grate through light copper tubing, which is used to cut down
weight. A spring-controlled relief valve is employed on this tubing
to keep the air pressure uniform, while the water supply is maintained
by a small, single-acting, ram type of pump, which is also driven by
the motor. The cooler is composed of gilled tubes placed vertically,
to permit any dirt or grit to fall into a well or sump placed at the
lowest part of the apparatus, and in which there is always a supply
of water to catch it. As it is necessary to clean and purify producer
gas before it can be used in a motor, a washer is always employed.
This is formed of a tube fitted with a screen and a set of baffle plates
and is maintained partly full of water at all times. The object of
the latter is to relieve the gas of all fine dust and grit that it carries in
suspension, and to accomplish this the gas is passed directly through
the water. From the washer, it passes to a gas bag, which is fed by
pressure from the producer, through the cooler and washer to the
control valve, this valve being automatically operated by the flexible
cover of the gas bag. As the engine draws in a charge, the bag
naturally contracts, causing the cover to open the control valve and
permitting the entrance of a fresh supply of gas from the producer.
The throttle is operated in the usual manner, an auxiliary air valve
being fitted to enable the driver to vary the strength of the nuxture
in accordance with the demands made upon the motor. It might
appear from the description that such a plant would necessarily be
cumbersome and weighty, but such is not the case. Longitudinally
it occupies less than one-fourth the space required for the six-cylinder
motor, while vertically, it extends at its lower end to about the level
of the axles and at its upper end not quite as high as the dash;
the fact that the weight of the complete producer and its auxiliaries
does not exceed 250 pounds, effectually disposes of the weight question.

Exhaqstive tests were carried out to demonstrate the practical
working of the plant, as well as its cost of operation as compared
with fuels such as gasoline and kerosene. Two producers were built,
one small enough to feed the single-cylinder, 3^horse-power motor
of a small runabout, which serves to show in what a very limited com-
pass the complete apparatus may be accommodated, while the other
was fitted to a car having a four-cylinder, vertical, 30-horse-power
motor. For actual service, a producer was mounted on the 40-horse-



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COMMERCIAL VEHICLES 189

power, six-cylinder bus mentioned. Coke was used as a fuel and
tests showed that to run the latter vehicle, 19J pounds of fuel and
two gallons of water were necessary per hour. Coke, of the grade
used for this purpose, costs about .3 of a cent per pound placed on
the car, making the cost of running a vehicle with an engine of this
size approximately six cents per hour, as compared with gasoline at
15 cents a gallon and kerosene at 10 cents, the consumption of liquid
fuel on the same car amounting to from two to four gallons per hour.
It will be evident that this results in an unusually favorable showing
for the producer.

The motor can be started within five to ten minutes from aU cold,
the operation merely consisting of getting the fire under way and
supplying air for a few minutes by means of the hand-crank attach-
ment to the blower. After this, the car runs the same as one using
liquid fuel. The driver has little additional work to perform than
where gasoline is employed, as the mixture is fed and controlled auto-
matically by the gas bag and its valve. During the tests in question,
speeds ranging from 3 miles to 40 miles an hour were attained, the
supply of gas being steady and under perfect automatic control at
all times.

While the foregoing will be of considerable interest as showing
the possibilities of solid fuel on the conmaercial vehicle, it is naturally
doubtful if any serious attempt will be made to develop it further while
the possibility exists of obtaining ample supplies of liquid fuel of one
sort or another at a cost so low as to give the commercial motor vehicle
its present inestimable superiority over horse traction. One of the
chief difficulties encountered at first in the use of producer gas in
stationary plants was the amount of fine dust and grit carried into the
cylinders by the gas, despite the washing process, and it is evident
that this condition would be aggravated where space and weight
limitations restrict ^the size and efficiency of the washer, the result
being a scoring out of the cylinder walls and a loss of motor efficiency.
On the whole, it seems quite probable that alcohol will prove the
legitimate successor of gasoline once the point is reached when the
cost of the former places it at an economic advantage.



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190 COMMERCIAL VEHICLES

TIRES

It may seem strange at first glance, that the matter of providing
the commercial vehicle with suitable tires should have presented
any problem for the designer to solve. Of all the materials that
might appear to be suitable for the tires of a business wagon, rubber
is the best adapted to the purpose for a number of reasons. This
is frequently but erroneously termed "hard rubber" as the rubber,
although usually solid, is not what is known as hard rubber, the latter
being a substance that has been vulcanized until it has assumed the
closeness of grain of very hard wood. Rubber is preferred for tires,
because of its ability to absorb vibration and because of its excellent
traction, the latter naturally being its chief advantage.

Steel. From this it will be apparent at once why steel tires
have not been employed — first, because they would not provide
sufficient traction, and second because the pounding, which they would
impose on every part of the mechanism would be ruinous. Steel tires
are employed on the Sampson road train, but it will be noted that
the driving wheels are equipped with cleats to give sufficient traction
and the speeds are low. In addition, the mechanisms of both the
tractor and the trailers are of the simplest form, designed to stand
the roughest kind of treatment. In view of the nature of the service
for which a motor road train is intended, and the character of the
country in which it is used, steel tires would doubtless form the only
practical solution of the problem.

Wood. Next to steel, wood appears to have advantages in this
field, which have not yet been fully realized. Its coefficient of fric-
tion with the ordinary road surface is far higher than that of steel
and its traction is accordingly much better. It also acts as a deadener
of vibration to some extent, though not as valuable for this purpose
as rubber. On the score of economy, however, it is vastly superior
to both steel and rubber.

So far as the writer is aware, the only instance in which wood
tires are now employed, is to be found in the Avery tractor, which
is really a 3-ton truck designed to meet practically all the require-
ments of farm use. In the wheels of the Aver}% hard wood plugs
are set on end around the periphery of the wheel, as may be noted
by referring to the illustration of this vehicle, Page 133. The device



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COMMERCIAL VEHICLES 191

seen outside the wood-tired wheels has been designed especially to
enable the vehicle to travel over soft ground, as in hauling plows,
and while it also comes into action when the car is acting as a tractor
on the road, it is not, strictly speaking, a tire. Wood has also been
experimented with in the shape of blocks set on end and fastened in
the felly of the wheel, but the fact that such a tire has never come into
use would seem to show that is was unable to meet the requirements.
The wood plug tires employed on the. Avery are said by the makers
of that machine, to prove very effective in the service for which they
have been designed.

Rubber. No diflSculty was experienced in the employment of
solid rubber tires on light and medium weight vehicles, and had the
conm[iercial car never outgrown the delivery wagon stage, there would
doubtless never have been any tire problem. As commercial vehicles
increased in capacity, however, the solid rubber tires grew in size to
correspond, and trouble was immediately encountered in the use of
anything larger than a six-inch tire in one piece on a driving wheel.
An eight-inch, one-piece, solid, rubber tire was manufactured for
use on the driving wheels of a heavy truck but proved an utter failure.
This was due to the fact that solid rubber is practically incompressible
— ^next to water, it is probably the least compressible substance known.

Bearing this in mind, the reasons for its failure as a large single
tire will easily be appreciated. Take a 5-ton truck as an example.
Loaded, the total weight on the tires would be at least 16,000 pounds,
depending on the weight of the vehicle itself. As ordinarily designed,
a heavy commercial vehicle carries about three-fifths of the entire
weight on the rear wheels, say 10,000 pounds in this case, which prob-
ably is very close to the reality. Such a truck, equipped with an
8-inch, one-piece, solid-rubber tire would doubtless have in contact
with the road surface at its driving wheels, an area of 8-inch by 2-inch
or a total of about 16 square inches for each wheel. As each dri\ing
wheel is carrying a load of approximately 5,000 pounds, this means
a pressure of nearly 310 pounds to the square inch at the point of
contact.

\Miile rubber is not compressible, it is elastic, which many
erroneously regard as the same thing. Due to this elasticity, the
rubber of the tire in contact with the ground, is forcibly squeezed out.
In other words, it is simply displaced owing to the great pressure.



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192 COMMERCIAL VEfflCLES

But as neither this, nor the remaining rubber in the tire can be com-
pressed to an appreciable degree, it must go somewhere. Its only
escape is from the rim of the wheel altogether and it either disrupts
the tire or pulls it off the rim. No form of mechanical fastening
that can be devised is suflScient to hold a large, one-piece rubber
tire on its wheel, and the idea of employing it in this form has had
to be abandoned. The action of rubber under great pressure
will illustrate the difference between elasticity and compressibility.
For example, the only difference between attempting to compress
rubber and a solid rock would be that the former would yield by dis-
placement, if free to do so, as in the case of a tire, which is only con-
fined laterally, while the latter would remain inert until the pressure
became suflScient to crush it.

This peculiarity of rubber was allowed for in two ways, first,
by splitting the rear tire into two units above a certain size, thus per-
mitting the wave of displaced rubber to bulge laterally to a greater
extent than where it was in one piece; and, second, by sectioning the

tire, or dividing it into blocks of
rubber, instead of a continuous
piece. By allowing just suflB-
• cient space between the blocks
to compensate for the amount
of rubber displaced by the
Fig. 108. Firestone Twin, Solid Tipe. pressure, these tires have
proven very effective in service. A continuous tire of the Firestone
dual or twin type is shown in cross-section in Fig. 108 and the following
weights are given by the manufacturers as representing the extreme
load per wheel that should be carried on solid rubber tires of this type :
For a 2-inch tire, 500 pounds per wheel; 2i-inch, 750 pounds;
S-mch, 950; 3i-inch, 1,375; 4-inch, 1,750; 5-inch, 2,000; 6-inch,
3,000; and 7-inch, 4,000 pounds weight per wheel. In the dual type
two 2i-inch tires have a capacity of 1,900 pounds, exceeding by 400
pounds that of two single tires of the same size. Two 3-inch, will
carry 2,500 pounds; two 3^, 3,500; and two four-inch — or a dual
four-inch as it is known — will bear 5,000 pounds per wheel. Fire-
stone tires of this kind are made with cross-bars of steel vulcanized
right into the rubber near the base of the tire and made an actual
part of it. The tire itself is immovably held in the channel by two



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COMMERCIAL VEHICLES 193

endless retaining wires which press firmly upon the shoulders formed
by the cross-bars. These dual tires have such an advantage over
the single tire, that the latter is now only employed on the lightest
vehicles.

The second and more successful solution cf the problem where
the very heavy vehicle is concerned, is shown in Fig. 109. This is the



Fig. 109. EeUy-Sprlngfleld Block Tire.

Kelly-Springfield block tire and in the form illustrated shows tires
appropriate for the front and rear wheels of 5-ton to 7-ton trucks.
Each block of rubber is independently fastened by being slipped
through an opening in a steel plate corresponding very closely to its
size. These 'blocks have a spreading base of strongly reinforced
material, so that when the steel rim is bolted in place they are very
firmly held. Four sections of steel rim are employed to each com-



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194 COMMERCIAL VEHICLES

plete wheel. The use of a tire composed of separate blocks not only
eliminates the tendency to creep on the rim or junip off altogether —
which marked the single-piece, large-sized tires — ^but it abo reduces
to a large extent, the internal or molecular action of the rubber, which
causes heating and is detrimental to tlie life of the tire. The space
between the blocks not only allows for the expansion or displacement
of the rubber, but also gives greater traction, acting somewhat after
the manner of a series of cleats, but without the disadvantages of the
latter. The block construction also makes the tire much cheaper
to maintain and repair, as where a section of a continuous solid tire
is accidentally cut or badly damaged, it involves an expensiver repair

during which the tire
must be out of service,
while with the block
construction; any one of
the units may be replac-
ed in a few minutes at
comparatively small ex-
pense. The metal frame
and the rubber blocks

are illustrated in Fig. 110.
Fig. no. Metal Tire Frame and Blocks. ^ ^j^^ ^j ^j^jg j^j^j ^f ^^^

average diameter is composed of from thirty to forty blocks, and for
carrying weights in excess of a certain load per wheel, are made in
dual form on the drivers, the blocks, in this case, being placed in stag-
gered relation, as shown by the illustration. Based upon wheels of
not less than 36 inches in diameter, the extreme carrying capacities
of tires of this tj^e are given by the makers as follows: For Scinch
tires, 1,200 pounds; 4-inch, 1,500 pounds; 5-inch, 2,000 pounds^
6-inch, 2,800 pounds; 7-inch, 3,500 pounds; and 8-inch, 4,500
pounds per wheel respectively. Typical equipment for 4-ton and
5-ton trucks would be 4-inch single front and 5-inch dual rear; for
6-ton and 7-ton trucks, 5-inch single front and 6-inch dual rear;
while for 10-ton trucks, 5-inch single front and 7-inch dual rear.
One of the wheels of a 10-ton Hewitt coal truck equipped with tires
of this type is shown in Fig. 111.



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COMMERCIAL VEHICLRS 195

— — ~ — — ^ r

MANAGBMENT

The discussion of the taxicab has revealed the fact that the
success of a commercial vehicle in service depends to no little extent
upon its operation. The designer has made everj' effort to reduce
its mechanism and control to such absolute terms of simplicity that
little or no discretion is left to the driver, but it is naturally out of
the question to eliminate the personal equation entirely. The electric



Pig 111. Wheel of Hewitt 10-Ton Truck with Kelly-Sprtagfleld Dual Block Tire,

vehicle means the closest approach to this ideal and therefore has
an advantage where the grade of labor to be employed is in
question.

Conditions where the gasoline-driven vehicle are concerned,
are quite different, and to this fact has been due, in no small measure,
much of the reluctance displayed by business men who were experi-
enced in other forms of motoring, in adopting the power wagon for



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196 COMMERCIAL VEHICLES

their commercial needs. The training of a sufficient number of men
to properly handle gasoline trucks has presented a real problem,
which has l)een rendered far more difficult by the lure of pleasure-car
service at rates of compensation beyond the standards permissible
in the commercial field. Thus, many drivers, once they had mastered
the handling of a truck, immediately deserted this field for the much
higher compensation of a chauffeur's position, and the process of
training had to be repeated, often to the detriment of the vehicle
itself. The labor problem is one, however, that will provide its own
solution in the course of time.

The investment represented by the average commercial vehicle,
whether a delivery wagon or a truck, is so much greater than that
called for by a horse-drawn unit of the same typ^, or even its equiva-
lent in horse-drawn equipment, that radically different methods of
operation are called for if the overhead expense is to be kept down
to a working minimum. In other words it does not pay to permit the
motor vehicle to stand idle at all, if it can be avoided. That this
is possible to a very large extent is manifested by an ingenious arrange-
ment devised by the Wanamaker delivering service in New York.
In common with other establishments of its kind, the Wanamaker
store maintains a delivery service extending over a wide radius in
and around New York. Near-by deliveries are made direct by the
wagons which return to the store for reloading, while outlying dis-
tricts are served by wagons which receive their loads from a distribu-
ting station conveniently located in that district These distributing
stations receive their supplies in large quantities from the store
in motor trucks, such as the 3-ton Packard truck, Fig. 112,
several of these being employed for the purpose. But as a body of
the size shown would take some time to reload or empty of compara-
tively small packages, false bodies, or crates, have been designed to
fit snugly inside the real body of the truck. These false bodies are


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Online LibraryMedical Society of the State of North Carolina. AnCyclopedia of automobile engineering; a general reference work on the construction, operation, and care of gasoline, steam, and electric automobiles, instruction in driving, commercial vehicles, motorcycles, motor boats aerial vehicles, self-propelled railway cars, etc → online text (page 22 of 27)