Pump output flow direction vs. control handle rotation
Input shaft rotation CW CCW
Handle rotation A B A B
Port A flow (M1) Out In In Out
Port B flow (M2) In Out Out In
Servo cylinder (side) M5 (2) M4 (1) M5 (2) M4 (1)
Refer toInstallation Drawings on page 50 for handle connection requirements
MDC with Neutral Start Switch (NSS)
The neutral start switch (NSS) stops the prime mover from starting unless the pump is in neutral. When
the control is not in neutral position, the switch is disengaged, and the prime mover will not start. When
the control is in neutral position, the switch is engaged, allowing the prime mover to start.
MDC with neutral start switch
Non Feedback Proportional Electric Control (NFPE)
The Non Feedback Proportional Electric (NFPE) control is an electrical automotive control in which an
electrical input signal activates one of two proportional solenoids that port charge pressure to either side
of the pump servo cylinder. The NFPE control has no mechanical feedback mechanism.
The pump displacement is proportional to the solenoid signal current, but it also depends upon pump
input speed and system pressure. This characteristic also provides a power limiting function by reducing
the pump swashplate angle as system pressure increases.
Control response
Series 90 controls are available with optional control passage orifices to assist in matching the rate of
swashplate response to the application requirements (e.g. in the event of electrical failure). Software
ramp or rate limiting should be used to control vehicle response in normal operation. The time required
for the pump output flow to change from zero to full flow (acceleration) or full flow to zero (deceleration)
is a net function of spool porting, orifices, charge pressure, valve plates and other vehicle dynamics. A
swashplate response table is available for each frame indicating available swashplate response times.
Testing a prototype system to verify the software and orifice selection provide the desired response.
Series 90 pumps have many orificing combinations, however, software is the best means of controling
the swashplate response in normal operating conditions. Mechanical servo orifices should be used only
for fail-safe return to neutral in the event of an electrical failure.
Technical Information
Series 90 Axial Piston Pumps
Control Options
520L0603 • Rev 0804 • March 2016 37
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