Theory of Operation
The reduced pilot oil (28) control signal from the front
The function of pump regulators is to control the flow
or rear pump control valve is sensed by the piston (7)
of pilot oil to and from the servo piston large end (4) in
through hoses from control valve to a port at the top of
response to reduced pilot oil control signals from the
its respective regulator.
front and rear pump control valves (3) and supply oil
pressure signals from the front and rear pumps (22
The pump supply oil (29 and 30) from front and rear
and 20). Pump displacement (flow) is changed by
pumps is sensed through drilled passages in the pump
sending pilot oil to or releasing pilot oil from the servo
housing to the pump pressure inlets (12) in each
piston large end.
Pilot oil from the pilot pump (18) flows through drilled
The control signal from the speed sensing solenoid
passages in the pump housing to the small end of
valve is sensed through a hose to the speed sense
servo pistons and to the pilot oil inlet (8) at each
signal port (13) at the rear pump regulator and then by
regulator. Pilot oil pressure is maintained at the small
a steel line to the front pump regulator.
end of servo pistons and at the inlet of both regulators.