COMPONENT OPERATION / Pump Device Increasing Flow Rate (Regulator Operation with Flow Rate Control Pressure Decreasing) 1. When fan pump control solenoid valve (17) is ac- tivated, flow rate control pressure Pi in proportion to the movement of fan pump control solenoid valve (17) is routed to pilot piston (22) through spool (16). When pilot pressure Pi decreases, pilot piston (22) moves to the left until pilot piston (22) balances with spring (20). 2. Pilot piston (22) moves lever 1 (18) through pin (21). Lever 1 (18) rotates clockwise about pin (19) fixed to the axial plug. 3. Pin (7), which is attached to feedback lever (13), is inserted into hole (23) of lever 1(18).
Therefore, feedback lever (13) rotates counterclockwise about pin (14) by the turning of lever 1 (18) and moves spool (2) to the left. 4. When spool (2) moves, the large chamber in servo piston (15) is connected to the hydraulic oil tank though spool (2). As own pump delivery pressure P3 acts on the small chamber, servo piston (15) moves to the left. 5. As the pump displacement angle increases ac- cording to the movement of servo piston (15), pump delivery flow rate increases. 6. When servo piston (15) moves, feedback lever (13) moves through pin (14). As neither pilot pis- ton (22) nor lever 1 (18) moves, feedback lever (13) rotates clockwise about pin (7) and moves spool (2) to the right.
When the notches on sleeve (3) and spool (2) are closed completely, the large chamber in servo piston (15) is not connected and servo piston (15) stops moving. 7. With the above operation, pump delivery flow rate decreases according to increasing amount of flow rate control pressure Pi. NOTE: Refer to the pilot circuit in Hydraulic Sys- tem group / SYSTEM. Q (Flow Rate) Pi (Flow Rate Control Pressure) 16 Pr To Fan Motor Pi 17 22 3 2 13 P3 Pilot Pump 15 14 Fan Pump T1J1-03-01-023 T3-1-20