Primary Hydraulic Power System Static Description (A.10.A - C.30.A.20) - New Holland CX720 Repair Manual

DISTRIBUTION SYSTEMS - PRIMARY HYDRAULIC POWER SYSTEM
PRIMARY HYDRAULIC POWER SYSTEM - Static description (A.10.A
- C.30.A.20)
The high pressure circuit operates all of the work hydraulics and steering. The circuit is fed by a closed centre load
sensing variable displacement pump (4). Oil is drawn by the pump, from the main reservoir, shared with the hydro-
static system, through the inline pressure filter to the mainframe valve block.
The oil enters the main frame valve block at the priority valve slice and there the oil is split, dependant on demand, to
the steering valve, which has priority, or to the other hydraulic functions.
The unloading tube control, drum variator control and header height control are served by the main frame stack.
The straw elevator and header reverser, lateral flotation control, reel vertical and horizontal adjustment and reel speed
control are served by the straw elevator stack valve. The straw elevator stack valve is an extension of the main
frame stack valve and is connected with pressure (31a), return (31b), and load sensing lines (31c), via quick release
couplings.
The last section of the straw elevator stack valve is a flush valve. This valve allows a very small oil flow through the
stack valves, when no services are being operated, allowing warm oil to bring the stack valve assembly gradually up
to temperature.
The circuit return oil flows through to the return side filter back to the pump or to the reservoir.
The high pressure circuit is linked with the hydrostatic circuit. The hydrostatic pump (3) feeds the hydrostatic circuit.
The charge return and case drain oil flows through to the thermostat and cooler back to the reservoir or high pressure
circuit.
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