TM-9-2320-272-24-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4
JUNE 1998
TM-9-2320-272-24-1 - Page 54 of 1015
TM 9-2320-272-24-1
1-21. POWER SYSTEM OPERATION (Contd)
g. Powertrain System Operation.
The powertrain system is the same on all models in this manual except the extra-long wheelbase models,
which have an additional propeller shaft and center bearing. This system transmits engine power to the
axles to put the vehicle in motion. Major components of the powertrain system are:
Key Item and Function
1
2
3
ENGINE
- Provides power needed for powertrain component operation.
TRANSMISSION
-Adapts engine power to meet different driving conditions.
CENTER BEARING
- Provides support for propeller shaft to decrease vibration and wear on
universal joints (M927/A1/A2, M928/A1/A2, and M934/A1/A2 series only).
TRANSFER CASE
- Distributes power evenly to front and rear axles.
UNIVERSAL JOINTS
- Connections between two propeller shafts that permit one to drive the
other even though they may be at different angles.
DIFFERENTIALS
- Distribute power to left and right axle shafts.
AXLES
- Transmit power from differentials to rotate wheels.
PROPELLER SHAFTS
- Serve as driving shafts that connect transmission to transfer case and
transfer case to differentials.
4
5
6
7
8
1-44
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