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HYDRAULIC CIRCUIT
CASE TRAINING CENTER
AUGUST 2000
Swing Priority Variable Throttle Circuit
Swing pilot pressure is supplied to Pi2 port via shuttle valve and changes over the cut valve, and then,
connects the pilot port of the swing priority variable throttle to the drain passage. This secures swing force
for enforced digging operation with raised swing pressure even when the arm and swing are operated at
the same time.
Additionally, when trenching, boom up pilot pressure is supplied from Pi1 port and the supply of hydraulic
oil to the arm (1) is secured through moving the swing variable throttle to the right via the cut valve to open
the parallel circuit and the smooth trenching operation can be achieved even if the central bypass oil
passage is shut off by the boom (2) spool.
When swing and arm in or boom up is operated at the same time, the parallel oil passage remains
restricted, and the swing pressure is designed to be retained.
Priority is placed on swing before the cut valve.
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