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| Illustration 1 | g00524182 |
(1) Check valve for the primary steering system (2) Check valve for the secondary steering system (3) Supply hose from the secondary steering system (4) Backup relief valve for the secondary steering (5) Return hose from the steering metering pump (7) Supply hose to the steering metering pump (8) Backup relief valve for the primary steering (9) Pressure reducing valve (10) Return port to the steering hydraulic tank (11) Supply port from the steering piston pump (12) Low oil pressure switch for the steering pump | |
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| Illustration 2 | g01253212 |
(3) Supply hose from the secondary steering system (4) Backup relief valve for the secondary steering (5) Return hose from the steering metering pump (6) Steering check and relief valve (7) Supply hose to the steering metering pump (8) Backup relief valve for the primary steering (10) Return port to the steering hydraulic tank (12) Low oil pressure switch for the steering pump | |
The steering check and relief valve (6) is located on the frame behind the right front suspension cylinder. Secondary steering check and relief valve (6) acts as a manifold for the primary steering system and the secondary steering system. Pressure oil from the steering piston pump or the electric drive pump for the secondary steering and the brake release flows to the steering check and relief valve. The steering check and relief valve sends pressure oil to the steering metering pump or to the steering hydraulic tank.
Pressure oil from the steering piston pump flows through the supply port (11). The pressure oil opens primary steering check valve (1) and flows through supply hose (7) to the steering metering pump. Backup relief valve (8) for the primary steering will open if the pressure of the oil that is flowing from the steering piston pump is more than the pressure setting of the relief valve. The backup relief valve for the primary steering protects the steering system if the high pressure cutoff valve in the pressure and flow compensator valve fails. Pressure oil will then flow to the steering hydraulic tank through the return port (10) to the steering hydraulic tank. The pressure oil from the steering piston pump also flows to pressure reducing valve (9). Pressure reducing valve (9) protects low oil pressure switch (12) for the steering pump from high pressure oil. High pressure oil will damage low oil pressure switch (12) for the steering pump. Low oil pressure switch (12) for the steering pump will sense the pressure from the steering piston pump when the pressure of the oil is below the setting of pressure reducing valve (9). Pressure reducing valve (9) will shift if the pressure of the oil is greater than the pressure setting of the pressure reducing valve. Pressure reducing valve (9) will modulate in order to allow the steering pump oil pressure switch to sense the pressure setting of the pressure reducing valve.
The electric drive pump for the secondary steering and the brake release also sends pressure oil to the steering check and relief valve. The electric drive pump for the secondary steering and the brake release operates when steering pump oil pressure switch (12) senses low pressure or when the secondary steering and brake release control is pressed in the cab. Pressure oil from the electric drive pump for the secondary steering and the brake release enters the steering check and relief valve through supply hose (3). The pressure oil opens secondary steering check valve (2). The pressure oil flows from secondary steering check valve (2) to primary steering check valve (1). The pressure oil flows from primary steering check valve (1) through supply hose (7) to the steering metering pump. If the pressure of the oil from the electric drive pump for the secondary steering and the brake release is greater than the pressure setting of backup relief valve (4) for the secondary steering, then the relief valve will open. The backup relief valve for the secondary steering protects the secondary steering system if the main relief valve for the secondary steering in the electric drive pump for the secondary steering and the brake release fails. The pressure oil will flow to the steering hydraulic tank through return port (10) to the steering hydraulic tank.
Oil from the steering metering pump returns to steering check and relief valve (6) through return hose (5) from the steering metering pump. This oil flows out of return port (10) to the steering hydraulic tank.