HOUSING 4394806 - Caterpillar

Illustration 1 g00819486
Steering System Schematic (1) Selector valve (2) Check valve (3) Pressure line (4) Diverter valve (5) Relief valve (6) Secondary steering pump (7) Pressure reducing valve (8) Check valve (9) Check valve (10) Pilot control valve (11) Hydraulic oil tank (A) Line to warning switch (B) Brake return line (C) Implement supply line (D) Return line from implement (E) Return line from brake valve
Illustration 2 g00819543
Secondary Steering System Components (1) Selector valve. (6) Secondary steering pump. (11) Hydraulic oil tank. (12) Warning switch.
Illustration 3 g00819535
Steering Control Valve (4) Diverter valve. (5) Relief valve.The secondary steering system supplies steering oil if the primary steering pump fails. The secondary steering system can also supply pilot oil if the pilot oil pump fails.The secondary steering pump is a ground driven pump. Secondary steering is only available when the machine is moving. The secondary steering pump is located on the front of the output transfer gear housing. The secondary steering pump is a gear pump.During normal operation, oil from the steering pump flows through line (3). This high pressure oil keeps diverter valve (4) shifted downward. Oil from the secondary steering pump is then sent through the diverter valve to the hydraulic oil tank. Check valve (2) keeps the oil from the steering pump from flowing into the diverter valve.Selector valve (1) is used in order to alert the operator that the primary steering system has failed and secondary steering is being used. Warning switch (12) is used in order to alert the operator that the primary steering system has failed.High pressure oil is no longer sent through line (3) if the steering pump fails. The spring in diverter valve (4) will shift the diverter valve upward. Oil from the secondary steering pump (6) will then be allowed to flow through check valve (2). Check valve (8) prevents oil from the secondary steering pump from flowing back to the steering pump. Oil from the secondary steering pump then flows to the spool in the steering control valve. The secondary steering pump can also supply supplemental pilot oil for the steering system. Pressure reducing valve (7) lowers the oil pressure to approximately 1650 kPa (240 psi). The reduced pilot oil is then sent to pilot control valve (10) .Relief valve (5) is provided in order to prevent the oil pressure in the secondary steering system from reaching excessive pressures. Relief valve (5) is set to approximately 17300 kPa (2510 psi).