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| Illustration 1 | g06333375 |
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View of the steering control manifold (1) Control manifold (steering) (2) Relief valve (steering) (3) Accumulator drain solenoid (4) Flow control valve (fully closed) | |
Control manifold (1) is mounted on the inside left-hand frame rail and is located above the hydraulic filters. Control manifold (1) directs oil flow to the steering flow amplifier, brake manifold, steering accumulators, and the pilot signal pressure reducing valve for the hoist system.
Control Manifold (Steering) Ports
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| Illustration 2 | g06413948 |
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Port locations for control manifold (steering) (1) Control manifold (steering) (2) Relief valve (steering) (3) Accumulator drain solenoid (4) Flow control valve (closed - not used) (5) Port to tank (6) Pilot Supply to Hoist (7) Port to brake supply (8) Port to steering accumulator pressure gauge (9) Test port (10) Low steering pressure switch (11) Port from Priority Valve and Manifold (12) Ports to steering accumulators | |
Control Manifold (Steering) Hold Position
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| Illustration 3 | g06334449 |
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Control manifold (steering) (1) Control manifold (steering) (2) Port from Priority Valve and Manifold (3) Low steering pressure switch (4) Flow control valve (5) Relief valve (6) Port to tank (7) To steering accumulator (8) To steering accumulator (9) Port to accumulator pressure gauge (10) Accumulator drain solenoid (11) Port to steering control valve (12) Port to brake supply (13) Port to Hoist Pilot pressure reducing valve | |
When the engine is started, oil for the steering system is drawn from the hydraulic tank by the steering pump. Oil is sent through the steering oil filter to the priority valve that is inside the solenoid "Priority Valve and Manifold". The "Priority Valve and Manifold" gives priority to the steering system. The valve will remain closed until the pressure in the steering system reaches normal operating priority pressure. Once the steering system requirements are satisfied, the relief valve will open and shift the valve. Oil is directed to the final drive lube and the drive train cooling fan motor. The "Priority Valve and Manifold" provides flow to the drive train fan circuit and the final drive lube circuit.
Oil from the "Priority Valve and Manifold" flows through an orifice and check valve to control manifold (steering) (1). Inside control manifold (steering) (1), oil flows to relief valve (5) and through a check valve to the brake system. Oil then flows to accumulator drain solenoid (10), to steering accumulator ports (7) and (8), and to the steering control valve. After the oil pressure increases to a predetermined pressure in the accumulators, the steering pump will de-stroke. When a steering demand occurs, the accumulators supply the necessary oil flow for steering, and pressure in the accumulators decreases. The steering pump will automatically upstroke to maintain the oil pressure in the accumulators.
Note:
Accumulator drain solenoid (10) contains a manual override. When the Key start switch is turned OFF, the solenoid is energized and oil is directed from the steering accumulators to the tank. The manual override is spring loaded to the closed position. The manual override provides a method to release pressure in the steering accumulators manually. Relief valve (5) limits pressure in the steering system. Low steering pressure switch (3) monitors the steering system supply pressure and causes a cab dash low steering pressure indicator to illuminate if pressure is too low.