COMPONENT OPERATION / Pump Device Increasing Flow Rate 1. When own pump delivery pressure P3 decreases from D to C, compensating piston (1) and com- pensating rod (11) are returned to the left until compensating piston (1) balances with outer spring (10) and inner spring (9). 2. Compensating rod (11) moves lever 2 (4) through pin (12). Lever 2 (4) rotates clockwise about pin (5) fixed to the housing. 3. Pin (4), which is attached to feedback lever (7), is inserted into the hole of lever 2(13). Therefore, feedback lever (13) rotates counterclockwise about pin (14) by the turning of lever 2 (4) to move spool (2) to the left. 4.
When spool (2) moves, the large chamber in servo piston (15) is connected to the hydraulic oil tank through spool (2). As own pump delivery pressure P3 acts on the small chamber, servo piston (15) moves to the left. 5. The pump displacement angle increases accord- ing to the movement of servo piston (15) and pump delivery flow rate increases. 6. When servo piston (15) moves, feedback lever (13) moves through pin (14). As neither com- pensating rod (11) nor lever 2 (4) moves, feed- back lever (13) rotates clockwise about pin (7) and moves spool (2) to the right.
The notches on spool (2) and sleeve (3) are closed completely and the large chamber in servo piston (15) is not connected to the hydraulic oil tank, so that the movement of servo piston (15) stops moving. 7. With the above operation, pump delivery flow rate increases from B to A. (Flow Rate) B A C D (Delivery Pressure) Pr To Fan Motor 3 13 11 2 1 P3 9, 10 15 14 T1J1-03-01-017 Pilot Pump Fan Pump T3-1-26