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| Illustration 1 | g03494637 |
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(1) Main Control Valve
(2) Hoist Cylinders (3) Hoist Control Valve (4) Piston Pump (Brake, Hoist, and Fan) (5) Piston Pump (Steering and Hoist) (6) Pressure Switch (7) Pilot Control Actuator (8) Valve Spool (9) Pilot Control Actuator (10) Shuttle Valve (11) Orifice (12) Pressure Reducing Valve (13) Check Valve (14) Diverter Valve (15) Diverter Valve (16) Check Valve (17) Diverter Valve (18) Screen (19) Orifice (20) Check Valve (21) Check Valve (22) Orifice (23) Screen (24) Shuttle Valve (25) Shuttle Valve (26) Relief valve | |
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| Illustration 2 | g03494358 |
The tank contains oil for the following machine systems: Steering system, hoist system, brake system and fan drive system. Return line filters are located inside the tank.
Piston pump (5) is a variable displacement pump. The piston pump, which is driven by the engine, supplies oil to the steering system and the hoist system. The output of the piston pump is controlled by load sensing pressure.
Piston pump (4) is a variable displacement pump. The piston pump, which is driven by the engine, supplies oil to the braking system, the fan drive system, and the hoist system. The output of the piston pump is controlled by load sensing pressure.
Both piston pumps are connected to main control valve (1) and the main control valve controls the oil flow to all of the machine systems that are mentioned above. The main control valve ensures that the steering system receives priority flow from piston pump (5). The main control valve also ensures that the braking system receives priority flow from piston pump (4).
The steering system is operated by the steering wheel which is connected to the metering pump. The metering pump delivers oil to the steering cylinders in order to articulate the machine.
The braking system is operated by the brake pedal which is connected to the brake control valve . The brake control valve allows pressure from the accumulator to be transmitted to service brakes for the front axle. The brake control valve allows pressure from accumulator to be transmitted to the service brakes or to the service brakes for the rear frame depending on the configuration of the rear service brakes.
The parking brake is disengaged by pressure within parking brake accumulator when the machine is running. The parking brake is engaged by spring force when the engine is shut off or when the parking brake control is moved to the ENGAGED position by the operator.
The hoist system is operated by the hoist control in the cab. The hoist control is electrically connected to hoist control valve (3) which controls the flow of oil between the main control valve and hoist cylinders (2). The hoist control valve is operated by pilot pressure from the main control valve. The magnitude of this pilot pressure is electronically controlled.
The secondary steering system is supplied by the electric drive pump which is connected to the battery. The electric drive pump is activated if the pressure switch senses low pressure in the steering system or if a switch in the cab is pressed.