United States. Army. Ordnance Dept.

Handbook of artillery : including mobile, anti-aircraft and trench matériel online

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on the same propeller shaft are operated by the same lever. Having
a separate lever for each propeller shaft the steering clutches and
planetaries can be operated separately or simultaneously, as desired,
and in this way the vehicle is steered.


When both steering levers are in the forward position, the steering
clutches are engaged, and power is transmitted to both tracks at the
direct speed. By placing the right steering lever in the central or
neutral position, the right steering clutch is disengaged and power is
transmitted to the left track only and the vehicle can be made to turn
sharply to the right by applying the right steering clutch brake.

Placing the right steering clutch lever in the rear position sets the
planetary brake and reduces the speed of the right so that the
vehicle turns slowly to the right. In a similar manner the vehicle
can be turned to the left by the use of the left steering lever. Apply-
ing both planetaries at the same time furnishes a reduced uniform
speed to both tracks and a low gear ratio for a hard pull. With both


steering levers in neutral, or with the master clutch disengaged, both
brakes may be set simultaneously by the use of the hand lever located
between the two foot brake pedals. The speed and direction of the
direct drive is controlled by the selective transmission gear-shift lever,
which can only be operated when the master clutch is disengaged,
thereby breaking the power between the engine and the transmission.

The steel deck plates directly over the transmission case, planetary
brakes, and steering clutches are removable to provide ready access
for repairs and adjustments. Doors are provided in the sides of the
armor plate engine hood for the same purpose.

The equalizer arrangement is pivoted at the front end of the main
frame and operates so that one track, when passing over a log or


obstruction, forces th.3 track on the opposite side down into firm,
bearing with the ground, thus preventing the caterpillar tipping
sideways, or the front end riding up and running down with a jar
when the center of gravity passes over the obstruction. The forward
end of the caterpillar is covered with steel plates forming a protecting
nose when forcing its way through brush, trees, and other field

The rear deck plates under the gun breech are hinged so that they
may be folded back out of the way to enable the gun crew to load and
handle the gun from the ground.

A traverse of the gun relative to the caterpillar of 5 to the right
and 5 to the left is provided, which is sufficient for corrections and
accurate pointing. Any necessary traverse beyond this limit is
obtained by traversing the caterpillar vehicle under its own power by
the use of the steering levers. Under ordinary ground conditions an
all around traverse can be obtained in this way. The to 35 range
elevation of the standard wheeled carriage is retained in this mount.

A structural steel deck, with necessary guard railing is secured to
side plates of main frame, and extending over the entire length of the
tracks, thereby preventing accidents to the personnel during travel-
big, and may be conveniently used for mounting of the sight, tool
and spare part chests, etc., when deemed necessary.

This self-propelled caterpillar type unit has successfully demon-
strated its advantages, for, due to its mobility, it may readily be
transported from place to place under unfavorable ground and
weather conditions and is able to open fire immediately upon its
arrival in a position. The advantage of this type of machine having
artillery mounted directly on a vehicle with caterpillar treads for
military purposes lies in its ability, due to very low unit ground
pressure, to negotiate soft and uneven surfaces, imposible to the
usual type of power vehicle, except under the most extreme diffi-

Anti-aircraft guns are receiving careful attention with the view
of further development of easily maneuvered and quickly handled
pieces. They are mounted on self-propelled vehicles, as trucks or
caterpillars, or on some easily drawn vehicle such as an auto trailer.
They must of course be designed for all around and high angle fire.
Used as they are against swiftly moving aircraft, special guns of
high velocity and sights specially adapted to this work must be

Several changes are apparent in the trend of design for new field-
pieces of the wheeled type.

The desirability of wider traverse and higher angles of elevation
has led to the development of the split trail carriage for both guns

and howitzers. Many of the newer guns permit of as high elevation
as that of the howitzers.

Another development is that of interchangeable guns and howitzers
for the same carriage. For example, one type of carriage being de-
veloped is that for mounting a 75 millimeter gun or a 105 millimeter

The hydro-spring type of recoil mechanism seems to be almost
entirely superseded in the latest designs by the hydropneumatic
recoil mechanism.

The tendency in latest practice is to relieve the carriage from road
shocks as much as possible by the use of spring suspension and
rubber- tired wheels.

The desirability of small light fieldpieces which can be taken to
the front by the infantry has led to the infantry accompanying gun
and howitzer. Some of the latest experimental guns of this type are
2. 24-inch pieces so light that they are easily moved by man power.

In general, it will be seen from the above that future artillery
will more nearly approach the ideal, to the degree that the principles
of high power and swift transportation are incorporated in the design.


18322820 25




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DEC 18 1924

ft* Jd 19V


10 192S

'JUl 1 1 1960





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Online LibraryUnited States. Army. Ordnance DeptHandbook of artillery : including mobile, anti-aircraft and trench matériel → online text (page 19 of 19)