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 16 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 16 of 27)
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shows a six-cylinder motor of the Franklin air-cooled type.



Pig. 59. Section and Front View of Franklin Engine.

In the case of the truck, a different form of bonnet is employed, for
the motor is mounted directly beneath the footboard, as will be noted
from Fig. 58, which illustrates the complete Franklin chassis of the



Fig. 60. Suction Flywheel and Dissected Clutch of Franlclin Engine.

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96 COMMERCIAL VEHICLES

2,000-pound size. Further details of the motor construction are
shown in Fig. 59, the sectional view of which serves to illustrate the
auxiliary exhaust distinguishing the Franklin motor, while the con-
struction of the suction-blower flywheel, and the details of the multiple
disk clutch employed, are shown in Fig. 60. The same size motor
is employed on the 2,000-pound as on the 1,000-pound truck, and
the gear ratio on both is 0.83 to 1 . In fact, their specifications through-
out are practically identical, there being but 50 pounds difference
in the weight. The construction throughout is the same as that
of the Franklin pleasure cars, a laminated wood frame, tubular-front
and rear axles being used, the latter of the semi-floating type.
The springs are 40-inch, full-elliptic in front, with semi-elliptic and
coil springs in the rear. A sliding gear of the progressive type, giving
three forward speeds and reverse, constitutes this element of the
transmission, final drive being by propeller shaft. All brakes are of
the external, contracting type, one being placed in a drum on the
hub of each rear wheel, and one on the transmission drive shaft.
Instead of the usual bevel-gear drive, a worm and pinion are em-
ployed. The tire equipment consists of 37-inch by 5-inch Good-
rich quick-detachable pneumatics on the l,0()0-pound wagon, and
36-inch by 5i-inch tires of the same make and type on the larger
wagon.

Kiwx. As practice in the commercial field is not hampered by
prejudice or other unfounded bias as in the pleasure-car field,
but is based purely on results figured on initial cost and expense of
operation, the air-cooled motor is now much more in evidence in the
business wagon than it is in the car built merely for pleasure. Thus
no less than six different models of cars equipped with air-cooled
motors are listed by the makers of the Ejiox machines, who confine
themselves entirely to the water-cooled motor in pleasure-car design.
These range from the single-cylinder, 1,500-pound delivery wagon,
the motor dimensions of which are 5-inch bore by 8-inch stroke,
rated at 8 horse-power, up to the 3-ton truck, fitted with a four-
cylinder motor, having 4}-inch by 5i-inch cylinders and rated at 36
horse-power. Between these two extremes, there is the 2,500- and
3,000-pound wagon which has a two-cylinder, 5-inch by 7-inch, 20-
horse-power motor. The Knox motor is cooled by means of a large
number of successive series of corrugated pins which are tapped into



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COMMERCIAL VEHICLES 97

the outside face of the cylinder and are placed in staggered relation
to one another to deflect the currents of cool air passing over them.
Both the single-cylinder and two-cylinder cars are fitted with a
regulation planetary two-speed gear and chain drive, while the 4,000-
and 6,000-pound wagons having 36-horse-power, four-cylinder motors,
have a three-speed sliding gear of the selective type, Fig. 61. While
the latter naturally differ to a greater or less extent in detail from
many others of the same kind, their design may be regarded as
typical of those generally employed, so that the following description



Fig. 61. Knox Three-Speed Selective Transmissioii.

may be taken to cover the majority, with a few amendments, such as
the employment of annular ball-bearings, instead of the roller type
shown in the illustration. The main driving shaft may be seen
extending forward with a flange at its right-hand end for coupling to
the shaft from the clutch. Parallel with it are the operating rods
which carry yokes adapted to move the gears back and forth, accord-
ing to the position of the hand lever, which picks up one or the
other of these short operating rods, in accordance with which side of
it is moved, or, when in a sector, which slot of the latter it is in.
Thus the rod »nd its yoke farthest away from the main driving



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shaft, controls the first speed forward and reverse, the last-named
through an extra pinion underneath it, not plainly visible in the
illustration. The inner rod controls the second and third speeds
forward, and as shown, is in the second speed engagement. For
the third or high speed, usually known as the direct drive, the
two parts of the main driving shaft are locked together so that
the power of the motor is then transmitted directly from the
clutch to the bevel pinion and large gear without the intermission
of any other reduction. This large bevel also incorporates the
differential, which is mounted on the countershaft. At its outer
ends, this countershaft carries sprockets of small size, driving
by means of side chains to larger sprockets on the rear wheels,
these constituting a further reduction in the speed between the
motor and the drivers. On the high gear, the ratio is 6.75 to 1,
which, at 1,500 r. p. m. of the motor, equals 222 turns of the 36-inch
wheels with which the car is equipped, and is equivalent to a maxi-
mum speed of 22.6 miles per hour. The gear ratio of the second
speed is 1L81 to 1, and at the same motor speed, it turns the rear
wheels 127 times per minute, which is equal to 12.2 miles per hour.
The first, or low gear is 27 to 1, or 5.8 miles per hour, while on the
reverse, it is further decreased to 34.6 to 1, or 3.2 miles per hour.
A substantial lock is provided to prevent attempting to engage two
speeds, while a strong spring tends to throw the shifting lever into
the neutral position whenever it passes that point The complete
gearset and its case weighs 600 pounds.

Frayer-Miller, The Frayer-Miller is a further type employing
an air-cooled motor, and, in fact, was the first of its kind built in this
country to incorporate a blower for cooling the engine. This blower,
which is of the vane, or centrifugal tj'pe, takes the place of the fan
ordinarily employed on water-cooled motors and is driven by gears
from the crank shaft in much the same way, but, as its capacity has to be
much greater, the construction throughout is very much more substan-
tial. The blower delivers a large volume of air to a manifold which is
led up and along the top of the cylinders, opening into the upper ends
of hght air-jackets which surround the heads and \^orking length of
the cylinders. The latter are fitted with radiating flanges past which
the air is forced, issuing at the open ends of the bottom of the jackets.
Contrary to the usual practice, the talves are placed in a vertical



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plane and face one another in a special valve chamber mounted on
the cylinder head, thus getting the direct benefit of the cooling cur-
rent of air. As motor trucks and delivery wagons are run at slow
speeds and with frequent stops as compared with a pleasure car,
the blower system, represented by the Frayer-Miller and the Frank-
lin, is an advantage as it makes the cooling of the motor entirely in-
dependent of the speed of the car. In the truck types, the Frayer-
Miller is listed in IJ- to 2-ton and 3-ton sizes. Except for slight
differences of dimension, the specifications are practically identical
in both cases. The motor has four 4^inch by 5j-inch cylinders
and has a nominal rating of 28 to 30 horse-power. A selective sliding
type of gearset, providing four forward speeds and one reverse an(|
having its shafts mounted on annular ball-bearings, is employed.
This is connected by a short propeller shaft having two universals
to a countershaft, from which the final drive is taken to the rear wheels
by side chains in the conventional manner. The axles are solid
forgings of square section, 36-inch wood artillery wheels being used
on both trucks, with 4-inch single, solid-rubber tires front and 3J-
inch dual type on the rear of the larger machine, and 4-inch front and
5-inch single rear on the lighter type. The front springs are semi-
elliptic, with a three-member semi-platform suspension at the rear.
Both the foot brake and the emergency operate in drums on the driv-
ing wheels. The wheel base is 118 inches on the 2-ton and 128
inches on the 3-ton truck with a 66-inch tread, this permitting of a
loading space measuring 12 feet long by 56 inches wide in the cleai;.
Rapid. By referring to "Gasoline Types of Delivery Wagons,"
Page 53, it will be noted that chassis of the smaller size just described
are also listed as delivery wagons. This is the case with the Frayer-
Miller, the makers of which list the smaller of the above chassis, with
but slightly reduced dimensions, for delivery-wagon service. This is
likewise the case with the Rapid, which, for delivery work, is of
unusually substantial construction. In the case of the Rapid, the fol-
lowing differences in dimension suflSce to sum up the points of va-
riance between the one-ton delivery chassis, and the li-ton to 2-ton
light truck. The two-cylinder, horizontal, opposed motor has a 5J-
inch bore by 5-incli stroke with an output of 30 horse-power, as com-
pared with 24 horse-power for the smaller. 2-inch axles are employed
with 32-inch wheels front and 34-inch wheels rear, the total weight



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100 COMMERCIAL VEHICLES

of the chassis being 2,676 pounds, giving a comparatively high load
efficiency, even on a l^-ton basis.

But the difference between the requirements of heavy-duty trucks
— ^in which class may be included those of 3-ton capacity and upward
— and those of lighter weight is proportionately as great as the differ-
ence between the requirements of the pleasure car and the delivery
wagon intended for constant service. The ratio of increase in the
stresses imposed on the vehicle by an increase in the dead-load capacity
was frequently not given sufficient consideration in the design of
earlier trucks. It was often erroneously assumed that it was not
even necessary to increase power and dimensions in quite the same
proportion as the load increased. While this is true to a great extent,
and] particularly at the present time, it was not many years ago that
neither materials nor design were up to the requirements. For this
reason, some builders very prudendy adhered to the manufacture of the
lighter-capacity chassis for several years before attempting heavy-
duty trucks, the experience gained in the former field being utilized to
great advantage in the latter. The most common of early errors was
naturally that of attempting to use practically the same chassis for
commercial service as was used for the pleasure car. Under the
greatly increased strain of commercial service, clutches, transmis-
sions, and axles that did excellently on the pleasure car, here proved
an unremitting source of trouble, which did much to discredit some
of the first attempts.

A study of the conditions obtaining in the heavy-truck field, as
compared, with the requirements of lighter vehicles, is responsible
for the striking difference shown in the design of the Rapid 3-ton
and 5-ton trucks when placed beside those of the same cars for loads
up to 2 tons. ^ Instead of the two-cylinder, horizontal motor, a four-
cylinder, vertical motor, Fig. 62, with cylinders of 4j-inch bore by
5i-inch stroke, and giving 45 horse-power, is employed. By noting the
different ratings and cylinder dimensions of the various truck motors
described, it will be found that there is quite as much divergence in
this respect in the commercial field, as in that of the pleasure car.
Ample provision for lubrication — ^the prime necessity of the commercial
car motor — is made on the Rapid by installing a gear-driven force-
feed oiler with a capacity of 10 pints, a return pump taking care of
the surplus oil in the crank case. As there are few things about the



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mechanism of a truck so essential to its operation as adequate pro-
vision for continuous lubrication, the equipment for this should be one
of the first things looked to in examining a machine for its fitness for
heavy duty. . Next to this come the ignition and the cooling equip-
ment, as upon these two depend in very large measure the reliability
of the car. ■ The Rapid trucks are fitted with a Bosch high-tension
magneto — ^which constitutes an independent and self-contained sys-
tem of great dependability — and a reserve system comprised of a
four-unit vibrator coil and timer supplied by a set of storage cells.
Two sets of spark plugs are employed, thus making each system



FiR. 62. Rapid 45-H. P., Four-Cylinder, Vertical Motor.

entirely independent of the other. Tliis is an excellent feature, as
in the severe service which heavy trucks are called upon to perform,
every precaution must be taken to insure absolute reliability, and
while a high-tension magneto of standard make has proven to possess
the highest measure of reliability, it is essential that the possibility
of failure should be guarded against, as this might occur just at a time
when' a breakdown might mean the delay of a valuable load of mer^
chandise in transit. The battery system is also a great aid in starting



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102 COMMERCUL VEHICLES

the heavy motors usually employed on trucks, as the motor will often
take up its cycle simply by switching on the current, or with but little
cranking, although the magneto has now been developed to a point
which makes starting very easy, and thousands of cars carry no other
ignition equipment.

The Rapid motor is cooled by means of a large radiator, mounted
directly in front of the dash, the water being circulated by means of a
gear-driven centrifugal pump. This type of pump has the advantage
of permitting the water to circulate through it on the thermo-siphon
principle in case it breaks down, which is not the case with the gear
pump. The foregoing will make clear the reasons for the preference
accorded the types of equipment in question on the best makes of
trucks, the accessories in question now being regarded as standard,
though in the case of the oiler and pump, there are naturally modi-
fications of design to be found. So far as the remainder of its con-
stniction is concerned, the Rapid motor is designed along conven-
tional and generally approved lines.

This likewise applies to the construction of the chassis as a whole,
Fig. 03, every effort havihg been devoted to making it as substantial
as passible. A heavy girder type of frame is employed with unusually
large springs. The gearset is of the selective sliding type giving
three forward speeds and is incorporated in the same housing with the
differential on the countershaft. Heavy gears of wide face are used,
tlie shafts being mounted on Timken roller bearings. The gear
ratio is 7 J to 1 on the direct drive, giving a maximum speed of 10 miles
an hour. The clutch is a multiple-disk tj'pe, running in a bath of
oil, while the final drive is by means of heavy side chains, a feature
of the drive being the use of a Hedgeland equalizing axle in place
of the usual differential. This consists of a solid, one piece axle,
with an ingenious screw clutch device for driving the wheels, which
permits the outer one to run free when rounding comers. The front
axle is of 2i-inch by 3J-inch rectangular section, while the rear is a
3\-inch round steel section. Steering is accomplished by means of a
differential-screw type of gear. The wheel base is 138 inches, giving
a loading space of 12 feet in length. The weight of the complete
chassis is 6,000 pounds.

The suspension of the Rapid trucks is of the conventional semi-
elliptic front and half-platform rear springs, but is characterized by the



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COMMERCIAL VEHICLES 103

use of an auxiliary spring over the rear axle, to supplement the regular
springs ifrhen the truck is loaded beyond its normal rating. Trucks
of this type are intended for the service of brewers, ice, coal, and lum-
ber dealers, iron works, flour and sugar mills, and similar employment
involving the transportation of heavy loads.

'^The vehicle just described is rated as having 3-ton to 5-ton load
capacity, the same makers listing a heavier tj'pe designed to carry



Fig. el Rapid 5-Ton Chassis.

5 tons to 7i tons. Its specifications are the same with the exceptipn of
differences in dimension. A 60-horse-power motor is employed, the
frame being of 6-inch rolled steel channels, with proportionally
heavier axles and springs. The wheel base is 160 inches, giving a
loading space of 14 feet, while the weight of the chassis is 7,500 pounds.
American. The American trucks, which are listed in 1-, li- to
2-, 3-, and 5-ton sizes, are characterized by the use of a governed
motor, a sliding gearset in the smaller sizes, a wood frame, and a s|xjcial
type of planetary, with disk clutches on the 3-ton and 5-ton types.



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104 COMMERCIAL VEHICLES

The governor employed on the motor is of the centrifugal tvpe, a(?ting
directly on the throttle, and is a feature of considerable advantage in
commercial work, as it not alone prevents racing of the motor be-
tween gear changes — which is detrimental — but may also be set so
that the driver cannot exceed a certain speed. The 1 J- to 2-ton size
is fitted with a 35- to 40-horse-power motor, while a 55-horse-power
motor is installed on the 3-ton size, and a G5-horse-power on the 5-
ton size. Drive is by countershaft and double chain in the usual
form, in every case, an I-beam axle being used forward and a solid
square axlj in the rear. The suspension is of the conventional.



Fig. 64. American 5-Ton Truck with Wood Frame. ,

straight, semi-elliptic type forward and platform, three-point, spring
member in the rear. A view of one of the American chassis is shown
in Fig. 64.

Manhattan. The Manhattan trucks are of considerable interest,
as being among the first heavy types to be placed on the market in this
country, their successful operation in sizes ranging from 2 tons to 5
tons, during the past six years, affording ample evidence of the bene-
fits to be derived from a special study of the commercial problem,
which led their makers to employ the most substantial type of con-
struction right from the outset. The comparison of weights of chassis
for a given load shows that they are considerably heavier than some
of the others, so that their theoretical load efficiency would be corre-
spondingly less^ but the extra weight would appear to be justified by



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the record that these cars have made in sen ice. The motor is a four-
cyHnder, vertical tj'pe, of SJ-ir^ch bore by 6-inch stroke, but wiih
characteristic conservatism, the makers refrain from giving it a power
rating. Its output is probably 50 to 65 horse-power at a speed of
900 to 1,200 r. p. m.

The frame is of a heavy girder type and is carried slightly beyond
the forward face of the radiator in bow form, providing a bumper
which serves as protection for the radiator. This is a small detail



Fig. 65. Mack Transmission Used on Manhattan Trucks.

but is of considerable value in commercial sen'ice as bumps are not
infrequent and the radiator is the first thing to suffer. A leaky radi-
ator is not alone a source of considerable annoyance, but also of danger
to the motor, whi^ a honeycomb type of radiator is diflScult and ex-
pensive to repair. One of the features of the Manhattan trucks is the
employment of an individual-clutch change-speed gear, Fig. 65.
WTiile this apparently does not differ from the ordinary sliding type,
Fig. 61, it will be noted upon closer examination that the gears are
not designed to slide, but remain constantly in mesh. \Vhen out of
engagement, they are idle on the shaft, being locked by positive



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clutches controlled by the usual shifting lever operating in a standard
form of H-gate.

The gears, of large diameter and wide face, are carried on sub-
stantial shafts supported on Hess-Bright ball bearings. The dif-
ferential is of the bevel type and is enclosed in the same housing as
the gearset, this housing being supported at its after end by the
coimtershaft. From the latter, the drive is taken to the rear wheels
by heavy side chains. The countershaft also carries two large drums
of wide face, to which contracting bands are applied as brakes, the
stresses of braking thus being balanced by the differential as well as by
the usual equalizing gear. Internal-expanding emergency brakes
are fitted on the driving wheels. The first service in which the
Manhattan cars were generally employed was that of sight-seeing cars,
station buses, and the like, having a capacity ranging from 12 to 22
passengers. A large number of these cars, fitted with various types
of closed and open bodies are now in service. The ccmstruction
throughout has been standardized by the makers, the same motor
and gearset being used on all sizes from the 12-passenger, sight-seeing
car up to the 5-ton truck, the difference naturally being in the manner
of utilizing the power by varying the gear ratio between the motor
and driving wheels. The small buses and sight-seeing wagons con-
sequently are capable of speeds up to 25 'miles an hour, while the
heavy trucks run from 10 to 12 miles an hour loaded, and up to 15
or 10 miles empty. Owing to the gear ratios necessary to give these
low speeds of travel, especially on the first and second gear changes,
it would be necessary to race the motor unduly to exceed the speed-s
in question. For commercial service, the Manhattan chassis are
built with capacities of 2, 3, 4, and 5 tons.

Packard, The Packard 3-ton truck, built by the manufacturers
of the pleasure cars of the same name, affords an excellent example
of the progress that has been made in the development of a truck
designed to meet the most severe business requirements. It is the
result of several years' study of the problem and was only placed on the
market after a thorough trying out of the vehicle from every point of
view. The motor is of the four-cylindei^, vertical, water-cooled, four-
cycle type and is characterized by the same features of design which .
distinguish the motor employed on the pleasure car. As is the case
on the latter, the motor is carried on the forward end of the chassis



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108 COMMERCIAL VEHICLES

under the same type of bonnet, Fig. 66. The cylinders have a 4i-
inch bore and a 5i-inch stroke, the motor being designed to develop
24 horse-power at an unusually moderate speed. This makes it
capable of giving an output largely in excess of this by simply in-
creasing the speed of the motor, which, due to its low normal r. p. m.
rate has a wider range of acceleration without racing than is
possible with a higher initial rate. An unusually flexible motor thus
results, and the importance of this feature may be appreciated when
the low speeds of travel to which the commercial vehicle is necessarily
restricted are borne in mind. In other words, the discrepancy be-
tween the motor speed and that of the car is greatly reduced, and the
necessity for employing a high gear ratio correspondingly lessened.

Cooling is accomplished by means of a cellular radiator, the
water being circulated by a centrifugal pump of large capacity. The
radiator itself is carried on a trunnion type of mounting which pre-
vents it being affected by any torsional stresses set up by the twisting
of the frame. An Eisemann high-tension magneto is employed for the
ignition, with a set of storage cells for resen^e current. The clutch is
what is known as a dry-plate type, in which a floating disk having both
of its surfaces covered to a large extent with cork inserts, is clamped
between plain metal disks secured to the flj^heel and the trans-
mission shaft respectively. Changes of speed are effected by means
of a sliding gear of the same type as is employed on the Packard
pleasure cars, final drive taking the form that has become standard
practice in American heavy-truck design, viz, double side chains. To
overcome the whipping and jerking effect on the chains occasioned


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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 16 of 27)