SUPPORT GP-ENGINE 4N1823 - Caterpillar

Illustration 1 g01395706
Hydraulic schematic for the steering system (1) Left steering cylinder (2) Right steering cylinder (3) Brake release cylinder (4) Steering release diverter valve (5) Steering control valve (6) Check valve (7) Pressure tap for the brake release system (8) Brake release sequence valve (9) Line to parking brakes (10) Line relief and make-up valve (11) Line relief and make-up valve (12) Spool (13) Steering pilot control valve (14) Connection for recovery hook type brake release system (15) Shuttle valve (16) Steering relief valve (17) Check valve (18) Steering system pressure tap (19) Implement and steering neutralizer valve (20) Parking brake oil pressure switch - electronic transmission control (21) Secondary steering diverter valve (if equipped) (22) Parking brake oil pressure switch - remote control light (23) Orifice (24) Hydraulic oil cooler (25) Primary steering flow switch (if equipped) (26) Check valve (27) Parking brake control valve (28) Line to parking brakes (29) Pressure tap for the parking brake and the pilot system (30) Left neutralizer valve (31) Pressure tap for the steering pilot system (32) Right neutralizer valve (33) Steering pilot pressure reducing valve (34) Check valve (35) Line from the implement lift circuit (36) Selector and pressure control valve (37) Secondary steering pump (if equipped) (38) Hydraulic tank (39) Pilot oil pressure reducing valve (40) Portable hydraulic pump quick connect coupler (41) Line to brake accumulator charging valve (42) Breaker relief valve (43) Portable hydraulic pump quick connect coupler (44) Brake and pilot pump (45) Steering pump (46) Implement pump (47) Hydraulic oil filters (48) Check valveThe pilot circuit controls the movement of spool (12) in steering control valve (5) .With the engine running, oil flows from hydraulic tank (38) to brake and pilot pump (44). The pump is a vane type pump.Pressure oil then flows through check valve (48) to pilot oil pressure reducing valve (39). Part of the oil also flows to the brake accumulator charging valve through line (41) .From pilot oil pressure reducing valve (39), oil flows through check valve (26) to selector and pressure control valve (36) and implement and steering neutralizer valve (19) .While the brake and pilot pump is supplying oil to the pilot system, selector and pressure control valve (36) will block the flow of alternate oil into the steering pilot system.If brake and pilot pump (44) fails, or oil is not available, then selector and pressure control valve (36) will allow alternate pilot oil to flow into the steering pilot system from the lift cylinders. If oil is not available from the lift cylinders, selector and pressure control valve (36) will allow alternate pilot oil to flow into the steering pilot system from steering control valve (5) .Pilot oil flows through implement and steering neutralizer valve (19) to the hydraulic pilot circuit and through steering pilot pressure reducing valve (33) to steering pilot control valve (13). Implement and steering neutralizer valve (19) diverts oil flow to hydraulic tank (38) when the operator station door is open.When the STIC