Drive System - Wacker Neuson RD 12A Repair Manual

Drive System

5 Drive System
Background The hydraulic system is powered by two pumps (exciter and drive) mounted in tandem—
connected along their shafts through a solid-mounted coupling—and driven directly by the
engine crankshaft through a flex coupling.
Drive Pump The drive pump is a variable displacement, axial piston pump and includes an integral
charge pump.
Flow through the drive pump is controlled by varying its displacement through the move-
ment of the control lever coupled to the pump's control shaft. This allows a full range of
operating speeds in both forward and reverse.
The drive pump includes pressure test ports for the drive system.
The drive pump also includes the towing valve which, when open, allows oil flow to
bypass the drive motors.
Drive Motors There are two drive motors—one mounted to each drum.
The drive motors are plumbed in series.
System filters The hydraulic tank is equipped with a strainer at the fill port to trap large objects or parti-
and strainers
cles which may accidentally fall into the tank while adding hydraulic fluid.
Additional system protection is provided by a suction filter mounted in-line with the
exciter pump inlet.
The hydraulic system is protected by a return-line filter which removes dirt particles
down to 10 microns and includes a flow bypass for cold weather start-up.
Troubleshoot- When troubleshooting drive system problems, do so in the following sequence:
ing sequence
1. Check the tow (bypass) valve.
2. Check the function of the drive control cable.
3. Pressure test the drive pump and relief valve.
4. Check the drive motors for binding.
5. Check the oil flow through the drive motors.
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RD 12/RD 12A