COMPONENT OPERATION / Pump Device Decreasing Flow Rate (Regulator Operation with Flow Rate Control Pressure Decreasing) 1. When flow rate control pressure Pi from pump control solenoid valve (4) decreases, spool (2) is returned to the left until spool (2) balances with spring (7). 2. Pressure oil acting on pilot piston (3) is returned to the hydraulic oil tank via through pump control solenoid valve (4). 3. As spool (2) moves to the left, own pump delivery pressure P1 is routed into the large chamber in servo piston (11) through check valve (6), sleeve (1) and spool (2).
Although own pump delivery pressure P1 is also routed into the small chamber in servo piston (11), servo piston (11) moves to the right due to the difference in pressure receiving areas. 4. As servo piston (11) moves to the right, feedback lever (10) rotates counterclockwise around pin (9). 5. As the top end of feedback lever (10) is connected to sleeve (1) by pin (8), sleeve (1) moves to the left. Servo piston (11) continues to move until the notches on sleeve (1) and spool (3) are closed completely. 6. With the above operation, the pump displacement angle is reduced and pump delivery flow rate decreases.
Decreasing amount of pump delivery flow rate is proportional to that of flow rate control pressure Pi. 5 To Pilot Valve Psv 4 6 Pi 3 7 8 2 9 10 1 P1 T1J1-03-01-005 11 Pilot Pump Main Pump T3-1-10