MANIFOLD GP-CONTROL 3669955 - Caterpillar

Illustration 1 g00316628
Secondary Steering Pump (1) Large pump section (2) Small pump section (3) Outlet to steering control valve (4) Plug (5) Plug (6) Seat (7) Passage (8) Inlet from tank (9) Passage to pump outlet (10) Check valve (11) Passage (12) Spool (13) Passage (14) SpringThe secondary steering pump operates only when the machine moves forward. When the machine moves forward, oil is pulled in through inlet (13) by the pump gears in small pump section (2) and large pump section (1) .Oil from small pump section (2) passes through outlet (3) to the steering control valve.Output oil from large pump section (1) is controlled by valve spool (9) . When sufficient engine RPM is maintained, pilot pressure from the steering pump enters through passage (10) . Valve spool (9) overcomes the force of spring (7) . Valve spool (9) moves in passage (8) . This causes oil flow from the large pump section (1) to flow around valve spool (9) . Then, the oil flows through passage (14) back to the inlet side of the large pump section (1) . This means that only oil flow from the small pump section flows to the steering control valve.When the machine is moving and the engine RPM decreases below a sufficient speed or the engine stops, the pilot pressure from steering pump (31) will decrease. The force of spring (7) positions valve spool (9) in passage (8) . Oil flow from large pump (1) is directed through check valve (11) and passage (12) . The output of both large section (1) and small section (2) then flows through outlet (3) to the steering control valve.If the machine moves backward, the secondary steering pump will not send oil to the steering control valve. When the machine moves backward and the main steering pump fails, the machine cannot be turned.