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| Illustration 1 | g00627949 |
Steering, Suspension, and Hoist Systems (1) Steering metering pump (2) Pilot oil supply from the brake system (3) Hoist control valve (4) Hoist cylinders (5) Tailgate cylinder (if equipped) (6) Counterbalance valve (if equipped) (7) Drain valve (8) Suspension cylinders (9) Suspension accumulator (10) Shut off valve (11) Hoist pump (12) Check valve (13) Secondary steering pump (14) Tank (15) Steering pump (16) Shuttle valve (17) Check valve (18) Signalling and reducing valve (19) Check and combiner valve (20) Lowering control valve (21) Steering cylinders (22) Tank | |
Tank (22) contains oil for the steering system and tank (14) contains oil for the hoist and brake systems. Return line filters are located inside the tanks.
Primary steering pump (15) is a variable displacement piston pump. The steering pump is driven directly by the engine. The output of the steering pump passes through signalling and reducing valve (18). The output of the steering pump is controlled by load sensing pressure.
The secondary steering pump (13) is a gear type pump. The pump is driven by an electric motor and the pump is controlled by the Electronic Control Module (ECM). The ECM activates the secondary steering pump if the pressure switch shows a low primary steering pressure. The pressure switch is operated by the primary steering pressure.
The outlet of the steering pump and the outlet of the secondary steering pump are connected to check and combiner valve (19). Check and combiner valve (19) supplies steering metering pump (1). Test points for primary steering pressure and secondary pressure are installed in the check and combiner valve.
Hoist pump (11) is a gear type pump. The pump is mounted on the torque converter and the pump is operated whenever the engine is running.
Hoist control valve (3) operates hoist cylinders (4) and tailgate cylinder (5) (if equipped). The hoist control valve is a spool valve. The hoist control valve is operated by pilot pressure. The hoist control valve is electrically controlled. Pilot pressure is supplied from the brake system.
If the dump body is fully raised and the engine cannot be started, the dump body can be lowered with oil from the secondary steering pump. A cartridge valve in the hoist control valve is opened in order to connect the head end ports of the hoist cylinders to the tank. Lowering control valve (20) is opened manually by pulling down on the valve handle. This connects the secondary steering pump to the rod ends of the hoist cylinders.
Drain valve (7) and shut off valve (10) connect the hoist control valve to the suspension system and the tank. The shut off valves can be used in order to change the ride height of the front suspension.
Suspension cylinders (8) are connected to accumulator (9) which acts as a suspension spring. The suspension can be fully lowered by stopping the engine and opening both shut off valves. This allows oil from the suspension cylinders and the accumulator to drain to the tank. The suspension can be raised by fully lowering the dump body and opening shut off valve (10). Start the engine and hold the hoist control in the lower position. This will allow oil from the hoist pump to fill the front suspension cylinders.