The right output houses a combining planetary and brake pack
assembly, and the left output houses the hydrostatic steer reduction
gear train, a combining planetary, and a brake clutch pack assembly.
b. The Torque Converter and Lockup Clutch. The torque converter
(fig. 1-6) attaches directly to the engine. It is a three element,
polyphase converter that transmits the power from the engine to
It has a hydraulically operated automatic
converter lockup clutch to improve speed range coverage and
automatically applies the lockup clutch.
When lockup occurs, the
engine driven pump locks with the turbine element of the converter.
c. The Input Gear Train.
The input gear train (fig. 1-6)
receives power from the torque converter.
The gear train transfers
the power to the beveled input gear (fig. 1-7) in the center section.
The bevel gears change the direction of the power to the transverse
plane of the transmission.
In other words, the beveled gears cause
the power to turn 90ƒ.
d. The Range Planetary Range Pack.
The range planetary pack
(fig. 1-7) consists of five hydraulically applied clutches and three
planetary gear sets that provide the four forward and two reverse
For this transmission to provide any of the forward and
reverse ranges, it engages two clutches at a time in various
combinations, with range shifts accomplished by changing a single
The gearing arrangement is basically the same as that used in
other X-series military transmissions and Detroit Diesel
Allison commercial transmissions.
e. The Hydrostatic Steer Unit. The hydrostatic steer unit (fig.
1-7) consists of a hydrostatic pump and motor.
They control the
differential steer system by providing positive steer ratio control
of the vehicle tracks under all conditions.
This feature is
particularly valuable at high speeds and on slippery terrain.
must noted that this feature is not available with force control
The hydrostatic pump receives its input from the same source as the
range pack. The output of the hydrostatic steer unit goes through a
reduction gregarine and connects to the combining planetary sun
gears. This arrangement allows the output of the unit to drive the
sun gears at equal speed but in opposite directions.