Specifications

Service Training
Page 4.2
Section 2
4.2.1 HYDROSTATIC TRANSMISSION
The transmission is composed of separate components consisting of a high pressure axial variable-
displacement pump with integrated control elements and 2 high pressure axial variable-displacement
motors. Each hydraulic motor is bolted to a 2-stage planetary hub reduction gear via an intermediate
housing that contains the disc brake so forming a compact drive unit for each traction wheel.
A flange-mounted tandem pump is connected to the shaft of the variable-displacement pump. The first
pump supplies boost pressure for the working hydraulics while the second one delivers the pressure for
the power steering system. A gear pump serving as delivery pump is driven via an auxiliary power take-
off on the engine.
With the proven double-pedal control, a travel control unit is used to select the travel directions, the control
pressures for regulating the variable-displacement pump (primary control) and the variable-displacement
motors (secondary control) as well as for adjusting the speed of the engine. The disc brakes can be operated
even when the engine is running by depressing the brake pedal located between the accelerator pedals.
A speed limiter prevents any overloading of the engine by the transmission. An engine stall during additional
loads by the working and steering hydraulics is prevented by the anti-stall device.
When reversing the direction of travel, a lock-out logic ensures that the engine speed does not rise until
the truck starts moving in the new direction.