Pilot pressure oil that is created by the pilot pressure reducing valve and is used by the operator controls to command the movement of nine primary valve spools in the main control valve. The nine primary valve spools, in turn, control the flow of the high-pressure oil to the implement cylinders and motors.
The main control valve determines the direction and speed of the implement cylinders and motors in proportion to the movement of the operator joysticks and travel lever/pedals. The nine primary valve spools control the following components:
- Right front travel motor (FORWARD and REVERSE)
- Left front travel motor (FORWARD and REVERSE)
- Left rear travel motor (FORWARD and REVERSE)
- Right rear travel motor (FORWARD and REVERSE)
- Right front stabilizer cylinder (RAISE and LOWER)
- Left front stabilizer cylinder (RAISE and LOWER)
- Left rear stabilizer cylinder (RAISE and LOWER)
- Right rear stabilizer cylinder (RAISE and LOWER)
- Steering cylinders (EXTEND and RETRACT)
The upper main control valve is situated in the hydraulic circuit between the main hydraulic pumps and the implement cylinders, the grapple cylinders and the cab riser cylinders. The main hydraulic pumps supply high pressure hydraulic oil to the upper main control valve.
Pilot pressure oil that is created by the pilot pressure reducing valve and is used by the operator controls to command the movement of eight primary valve spools in the main control valve. The nine primary valve spools, in turn, control the flow of the high-pressure oil to the implement cylinders and motors.
The main control valve determines the direction and speed of the implement cylinders and motors in proportion to the movement of the operator joysticks. The eight primary valve spools control the following components:
- Right boom cylinder (RAISE and LOWER)
- Grapple cylinder (OPEN and CLOSE)
- Stick cylinder (IN and OUT)
- Left boom cylinder (RAISE and LOWER)
- Grapple rotate (LEFT and RIGHT)
- Cab riser cylinders (FORE and AFT)
- Cab riser cylinders (RAISE and LOWER)
- Stick cylinder (IN and OUT)
The hydraulic system contains the following pumps: two main pumps that supply oil to both main control valves, a generator pump, a swing pump and hydraulic oil cooler pump.
The hydraulic return system has two back pressure manifolds that allow for a specific pressure to be maintained in the system when the engine is shut down.
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| Illustration 1 | g03400482 |
Top view of machine (1) Lower control valve (2) Upper control valve | |
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| Illustration 2 | g03400484 |
Right side view of machine (1) Lower control valve (2) Upper control valve | |
The hydraulic system contains the following pumps: two main pumps that supply oil to both main control valves, a generator pump, a swing pump and hydraulic oil cooler pump.
The hydraulic system has two main control valves. The lower main control valve operates the travel motors and the stabilizers. The upper main control valve controls the following: cab riser cylinders, boom cylinders, grapple and stick cylinders.
The hydraulic return system has two back pressure manifolds that prevent cavitation in the system by maintaining a certain amount of pressure.