FLANGE 1018679 - Caterpillar

Steering Pump in the Upstroking Position
Illustration 3 g01191713
Schematic of the steering pump (Drive-through feature)
(1) Load sensing port from steering control valve
(2) Pressure Compensator
(3) Flow compensator
(4) Port for the discharge pressure
(5) Port for the discharge pressure gauge
(6) Boost pressure port
(7) Destroke piston
(8) Weep holes
(9) Steering pump
(10) Suction port
(11) Upstroke piston
(12) Port for the actuator pressure
(13) Drain port
(14) Case drain ports
(15) Spring
(16) Spring
(17) Oil passage
(18) Oil passage
(19) Hydraulic tankUpstroking is an increase of pump displacement due to an increased load. When the system requires more flow, signal oil from the steering control valve flows through port (1).The signal oil pressure combines with the force of spring (15). This causes flow compensator spool (3) to move to the left. When the spool moves left, the spool blocks the flow of pump oil through passage (20).While flow compensator spool (3) is to the left, the oil in the chamber of destroke piston (7) can flow into passage (17). The oil flows past the cavity of spring (16), past flow compensator spool (3), and through passage (18). The oil then flows back to hydraulic tank (19).Oil from the steering pump flows through passage (21) and into the chamber of upstroke piston (11). The combined force of the spring in upstroke piston (11) and of the oil in upstroke piston (11) moves the swashplate toward the maximum angle that causes the pump to upstroke.Destroking
Illustration 4 g01191822
Schematic of the steering pump
(1) Load sensing port from steering control valve
(2) Pressure Compensator
(3) Flow compensator
(4) Port for the discharge pressure gauge
(5) Discharge port
(6) Port for boost pressure
(7) Destroke piston
(8) Weep holes
(9) Steering pump
(10) Suction port
(11) Upstroke piston
(12) Port for Actuator pressure
(13) Drain port
(14) Case drain ports
(15) Spring
(16) Spring
(17) Passage
(18) Oil passage
(19) Hydraulic tank
(20) Passage
(21) Oil passage
(22) Passage
(23) PassageDestroking is a reduction in pressure when pump output decreases. Destroking occurs when the signal oil pressure through line (1) decreases from lower loads. While the steering control valve is in the NEUTRAL position, and the spool is in the centered position blocking the flow of pump oil to the actuators. The pump pressure increases in order to overcome the flow compensators and the spool will shift to the right. When the pump oil pressure in passage (20) is greater than the force of signal oil pressure and of spring (15), flow compensator spool (3) will move to the right and oil pressure in passage (22) flows past spool (3). The oil then flows through passages (23) and (17). The oil then flows into the chamber of destroke piston (7).Destroke piston (7) is larger than upstroke piston (11). Because of this difference in size, the oil pressure that is acting against the destroke piston exerts a greater amount of force than the combined forces that are acting against the upstroke piston.The oil pressure that is acting against the destroke piston (7) overcomes the combined force of the oil and of the spring in the upstroke piston (11). This causes destroke piston (7) to move to the left.As destroke piston (7) moves to the