•
The manual displacement control is a high gain control: With only small movement of the control
handle (input signal), the servo valve moves to full open position porting maximum flow to the servo
cylinder. This is a high response system with low input force.
•
The integral override mechanism allows rapid changes in input signal without damaging the control
mechanism.
•
Precision parts provide repeatable, accurate displacement settings with a given input signal.
•
The double-acting servo piston is coupled to a spring centering mechanism. The servo control valve is
spring centered such that with no input signal the servo valve is open centered and thus no fluid is
ported to the servo cylinder.
Benefits:
•
- Pump returns to neutral after prime mover shuts down.
•
- Pump returns to neutral if external control linkage fails at the control handle or if there is a loss of
charge pressure.
Manual displacement control schematic
External control handle requirements
•
Torque required to move handle to maximum displacement is 0.68 to 0.9 N•m [6 to 8 lbf•in].
•
Torque required to hold handle at given displacement is 0.34 to 0.57 N•m [3 to 5 lbf•in].
•
Torque required to overcome the override mechanism is 1.1 to 2.3 N•m [10 to 20 lbf•in] with the
maximum torque required for full forward to full reverse movement.
•
Maximum allowable input torque is 17 N•m [150 lbf•in].
Pump displacement vs. control lever rotation
Technical Information
Series 90 Axial Piston Pumps
Control Options
520L0603 • Rev 0804 • March 2016 35
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