Inspect Manual Displacement Control
Disconnect the external control linkage from the control
handle and check for neutral operating with control
handle. Releasing control handle should allow the pump
to return to neutral. If operation is satisfactory with
external control linkage disconnected, the problem is not
in the hydrostatic transmission.
If operation is not satisfactory with external control
linkage disconnected from control handle, the control
may be misadjusted.
Adjustment procedures are
contained in this manual.
Before proceeding with control
adjustment the following inspection
Remove the cap screws holding the control in place,
and swing it away from housing and remove. Inspect
visible linkages, torsion spring, and O-rings. Inspect for
missing, plugged, or improper orifice.
Inspect System Relief Valves
When the problem occurs in one direction only,
interchange the relief valve cartridges to see if the
problem changes to the other direction. If so, one relief
valve cartridge is either malfunctioning or does not have
the proper setting. The first two (2) digits of the
pressure setting are stamped on the end of the
cartridge. Compare to machine specification.
The relief valves are factory set and
should not be disassembled further.
Inspect Shuttle Valve
Remove the two (2) hex plugs and the shuttle valve
parts. Inspect for broken or damaged parts and proper
orientation. Washers must go between spool and
springs. Inspect to see if spool moves smoothly in its
The spool and manifold are matched
and cannot be replaced separately.