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Service Manual
Operation
Electric displacement control (EDC)
Automotive control (FBA II B)
3-Position (FNR) electric control
Series 90 Pumps
The electric displacement control uses a Pressure Control Pilot (PCP) valve to modulate pressure balance
across the spring-centered four-way servo valve. The PCP valve converts a DC electrical input signal to a
hydraulic signal. The servo valve ports hydraulic pressure to either side of a dual-acting servo piston. The
servo piston rotates the swashplate through an angular rotation of ±17°, varying the pump's dis-
placement. The angular position of the swashplate is proportional to the EDC input.
The automotive control allows the operator to drive a vehicle similar to an automobile with an automatic
transmission. The automotive control includes a three-position electric control to provide direction
control.
This control utilizes a 12 or 24 Vdc electrically operated spool valve to port pressure to either side of the
pump servo piston. Energizing one of the solenoids causes the pump to go to its maximum displacement
in the corresponding direction. All functions of the three-position (FNR) electric control are preset at the
factory
520L0818 • Rev 0101 • August 2015
15
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