Electric displacement control (EDC)The electric displacement control uses a Pressure Control Pilot (PCP) valve to modulate pressure balanceacross the spring-centered four-way servo valve. The PCP valve converts a DC electrical input signal to ahydraulic signal. The servo valve ports hydraulic pressure to either side of a dual-acting servo piston. Theservo 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.Automotive control (FBA II B)The automotive control allows the operator to drive a vehicle similar to an automobile with an automatictransmission. The automotive control includes a three-position electric control to provide directioncontrol.3-Position (FNR) electric controlThis control utilizes a 12 or 24 Vdc electrically operated spool valve to port pressure to either side of thepump servo piston. Energizing one of the solenoids causes the pump to go to its maximum displacementin the corresponding direction. All functions of the three-position (FNR) electric control are preset at thefactoryService Manual Series 90 PumpsOperation520L0818 • Rev 0101 • August 2015 15
