If a transmission part is to be repaired, make sure
only good repairs are made. Makeshift or temporary
repairs should not be permitted, except in an emergency.
The principal purpose of repairs is to salvage
components that would otherwise be scrapped. The
decision as to whether apart is to be repaired rests upon
three factors; First, the practicality of the repair, (That
is, will the repair of the part return it to a near new
condition?); second, the cost of the repair job as
compared to the cost of a replacement; and third, the
availability of the replacement part. If replacement parts
are unavailable or in short supply, make every effort to
salvage as many parts as possible.
Small holes or cracks in the transmission case,
shifter shaft housing, or clutch housing maybe repaired
by welding or brazing, provided they do not extend into
the bearing bores or mounting surfaces. These pieces are
gray (cast) iron, and special techniques are required to
weld these materials satisfactorily; normally, ordinary
welding methods and materials are not suitable.
To assemble a transmission, use a reverse procedure
from that of disassembly. Check the manufacturers
manual for proper clearances and the wear limits of the
All parts, whether new or used, should be lightly
coated with lubricating oil. This is done immediately
after inspection or repair. Oiling the parts gives them a
necessary rust-preventative coating and facilitates the
Train your personnel to have all the necessary parts
on hand before the assembly operation begins. This
guarantees that the transmission can be completely
assembled without interruptions.
As a CM1, it will be your responsibility to test the
transmission after it is assembled. If all parts are
correctly assembled, the transmission gears will all
rotate freely without evidence of binding. Use a suitable
wrench to rotate the input shaft at least ten full
revolutions. Shift the transmission into all the speed
ranges. If the transmission is noisy, extremely loose, or
binds, it must be disassembled and further corrective
Transfer cases (fig. 11-9) are placed in the power
trains of vehicles to allow them to operate in mud, snow,
sand, and other unusual terrains. To do this, you have to
have driving power available at the front wheels as well
as the rear wheels so the vehicle will not get stuck.
Therefore, certain wheeled vehicles include a second
gearbox, called the transfer case. Its purpose is to take
the output power from the transmission and divide it so
Figure 11-9.Example of a transfer case assembly (5-ton truck, military).