MODIFICATION 2962480 - Caterpillar

Illustration 1 g03703922
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) Hydraulic oil level sensor (22) Pilot oil pressure reducing valve (23) Pilot oil filters (24) Line from parking brake control valveThe main components of the steering high-pressure circuit are hydraulic tank (20), steering pump (18), steering control valve (2), and steering cylinders (1). These components work together to provide the force needed to turn the machine.With the engine running, oil flows from hydraulic tank (20) to steering pump (18). Steering pump (18) is the center section of a three-section, gear type pump. The steering section of the pump provides pressure oil for the steering high-pressure circuit.The steering pump sends oil through the check valve in secondary steering diverter valve (7) to steering control valve (2). Check valves in secondary steering diverter valve (7) control the flow of the oil. When steering pump (18) is supplying enough oil to steer the machine, the check valves allow the oil to flow into and through the secondary steering diverter valve to steering control valve (2) .When steering pump (18) is not supplying enough oil to steer the machine, and the machine is moving in either the forward or reverse direction, check valves in secondary steering diverter valve allow extra oil from secondary steering pump (3) to flow through the diverter valve to steering control valve (2) .If the pilot oil from the steering metering pump has moved the valve spool in steering control valve (2) to either the right or left turn position, the oil from the steering pump will flow to steering cylinders (1). The pressure of this oil in the steering cylinders causes the machine to turn.When the machine is in the straight ahead travel position, the oil in steering control valve (2) cannot flow past the control valve spool. This oil flows out of the steering control valve through steering oil filters (6) and back to hydraulic tank (20) through screen (19).