CLAMP-BAND 3377325 - Caterpillar

Illustration 1 g01164001
Hydraulic schematic for the steering system (1) Steering cylinders (2) Steering control valve (3) Secondary steering pump (4) Steering lockout valve (5) Steering metering pump (6) Steering oil filters (7) Secondary steering diverter valve (8) Steering system pressure tap (9) Steering neutralizer valve for a left turn (10) Hydraulic tank breather (11) Steering neutralizer valve for a right turn (12) Check valve (13) Primary steering flow switch (14) Line to the hoist pilot circuit (15) Implement and steering solenoid valve (16) Line to the parking brake circuit (17) Brake and pilot pump (18) Steering pump (19) Screen (20) Hydraulic tank (21) Pilot oil pressure reducing valve (22) Pilot oil filters (23) Line from parking brake control valveThe pilot circuit controls the movement of the stem in steering control valve (2) .With the engine running, oil is drawn from hydraulic tank (20) by brake and pilot pump (17). Brake and pilot pump (17) supplies oil through check valve (12) to pilot oil pressure reducing valve (21). Pilot oil pressure reducing valve (21) maintains the pilot system at a constant pressure. Pilot oil pressure reducing valve (21) relieves excess pilot system pressure through a line to the hydraulic tank.Oil from pilot pressure reducing valve (21) flows through pilot oil filters (22) to implement and steering solenoid valve (15). When de-energized, implement and steering solenoid valve (15) stops pilot oil from flowing to steering lockout valve (4) and steering metering pump (5) .When energized, implement and steering solenoid valve (15) directs pilot oil flow to steering lockout valve (4) and steering metering pump (5) .Steering metering pump (5) is a small hydraulic pump that is used as a metering valve and as a directional control valve. When the operator turns the steering wheel, a spool and a sleeve rotate inside the metering pump. The oil flows to steering lockout valve (4). Steering lockout valve (4) stops oil flow from steering metering pump (5) to steering neutralizer valve (9) and steering neutralizer valve (11) when implement and steering solenoid valve (15) is de-energized.When implement and steering solenoid valve (15) is energized, steering lockout valve (4) allows the oil from steering metering pump (5) to flow to steering neutralizer valve (9) or steering neutralizer valve (11). The oil from steering neutralizer valve (9) and steering neutralizer (11) can flow to either end of the stem in steering control valve (2), causing the stem to move. When the stem moves, high pressure oil from steering pump (18) can flow to steering cylinders (1).