COMPONENT OPERATION / Pump Device Control by Own Pump Delivery Pressure 8. The notches on spool (2) and sleeve (3) are closed completely and own pump delivery pres- sure P3 does not act on the large chamber in servo piston (15), so that the movement of servo piston (15) stops moving. 9. With the above operation, pump delivery flow rate is decreased from A to B, and load of the pump is reduced. NOTE: This control is performed in case speed increases beyond the rated speed when starting. Decreasing Flow Rate 1.
When own pump delivery pressure P3 increases from C to D, compensating piston (1) moves compensating rod (11) to the right until compen- sating 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 counterclockwise about pin (5) fixed to the housing. 3. Pin (7), which is attached to feedback lever (13), is inserted into hole (8) of lever 2 (4). Therefore, feedback lever (13) rotates clockwise about pin (14) by the turning of lever 2 (4) and moves spool (2) to the right. 4. When spool (2) moves, own pump delivery pres- sure P3 acts on the large chamber in servo pis- ton (15) through spool (2).
Although own pump delivery pressure P3 acts on the small chamber, servo piston (15) moves to the right due to the difference in pressure receiving area. 5. The pump displacement angle reduces according to the movement of servo piston (15) and the pump delivery flow rate decreases. 6. As own pump delivery pressure P3 acts on com- pensating piston (1), although piston (15) moves, compensating rod (11) and lever 2 (4) do not move. 7. 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 counterclockwise about pin (7) and move spool (2) to the left.
(Flow Rate) B A C D (Delivery Pressure) Pr To Fan Motor 22 3 2 13 1 P3 9, 10 15 14 Pilot Pump Fan Pump T1J1-03-01-015 T3-1-24