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HYDRAULIC CIRCUIT
CASE TRAINING CENTER
AUGUST 2000
Arm In Load Holding Valve Circuit
When arm in is operated, pilot pressure is supplied at 5b51 and arm (1) spool is changed over. At the same
time, pilot pressure, which is supplied from Ps2, acts on the poppet of the load holding valve, and the
poppet is opened.
Then, the hydraulic oil in the spring chamber of the load holding check valve is returned to the tank line via
the load holding valve poppet. The pressure in the spring chamber of the load holding valve check
decreases and the check is released. The hydraulic oil at the rod of the arm cylinder is returned to the tank
line, the arm cylinder extends and the arm is in.
Arm In Forced Recycle Circuit
The return passage for the rod is throttled at the forced recycle release valve and recycle forcibly the
returned oil to the bottom side.
When the load pressure is high at the bottom side, the forced recycle valve is changed over to the left and
the opening of the tank passage becomes larger and no recycle occurs.
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