Secondary Hydraulic Power System Static Description (A.12.A - C.30.A.20) - New Holland CX720 Repair Manual

DISTRIBUTION SYSTEMS - SECONDARY HYDRAULIC POWER SYSTEM
SECONDARY HYDRAULIC POWER SYSTEM - Static description
(A.12.A - C.30.A.20)
Low Pressure Circuit
The low pressure circuit (25 bar [363 psi]) operates the main, unload and feeder engagement clutches, parking brake
and optional chaff blower.
The circuit is fed by a gear pump (5) mounted on the high pressure closed centre load sensing (CCLS) variable
displacement pump, used for the high pressure system.
The low pressure circuit uses the main gearbox oil for its reservoir. The oil is drawn from the gearbox and pumped
through the chaff motor valve block, when fitted and onto the pressure filter, to the low pressure valve block, which is
located on the left hand side of the combine at the rear end of the engine.
There the oil is directed, via solenoid valves, to the clutches and handbrake.
The low pressure is regulated by a relief valve located on valve block. Excess oil from the relief valve passes through
the cooler and is then directed to the lubrication circuits for the main and unloading clutches. The lube pressure is
regulated by a check valve set at 2.75 bar (40 psi). Excess oil from the lube check valve is returned to reservoir.
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