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Chapter 11 Troubleshooting Transmissions, Transfer Cases, and Differentials | Up
Construction Mechanic Advanced - Construction methods and practices | Next
Table 11-1.—Troubleshooting Transmissions (5-ton military) |
in figure 11-2. Consequently, it is not possible to discuss
all makes and models that you may encounter in the
Navy. The information contained in this section is
general; for problems and procedures on any particular
transmission, consult the manufacturer’s manual.
It is seldom that the transmission of a vehicle is
manufactured by the same company that manufactured
the vehicle. Some manufacturer who specialized in
building automotive parts generally makes the
transmission and sells it to the vehicle manager. A
nameplate attached to the side of the transmission case
will have the manufacturer’s name and the model
number of the transmission. The Spicer Company, for
instance, uses a four digit number for a model number,
such as 8051. The third digit of the number indicates the
number of forward speeds available in that particular
transmission. Therefore, the model 8051 is a five-speed
transmission.
If a transmission does not have a nameplate, refer
to the vehicle manufacturer’s manual for identification.
TROUBLESHOOTING TRANSMISSIONS
It is important that transmissions troubleshooting be
done by trained, experienced mechanics. Many times an
operator will report transmission noise on the Operator’s
Trouble Report, when, in fact, the noise maybe coming
from some other component of the power train of the
vehicle.
Noises that appear to come from the transmission
but actually originate at some other point are many and
varied; for example, unbalanced propeller shaft,
defective wheel bearings, or damaged tires on a vehicle
may cause noises that are transmitted to the transmis-
sion. These noises have no particular or characteristic
sounds that would indicate their origin; therefore, they
are difficult to identify.
Torsional vibration is one of the most frequent
causes of noises that appears to be in the transmission,
but actually originates outside of it. Included among
these possible outside torsional vibrations are the
following:
1. Propeller shaft (drive shaft) out of balance
2. Worn universal joints
3. Drive shaft center bearings loose
4. Worn and pitted teeth on axle pinion and ring
gear
5. Wheels out of balance
Figure 11-2.—Typical example of a heavy-duty truck transmission.
11-2
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