Motors: expansible chamber type – With motive fluid valve – Inlet fluid supplemented by controlled fluid pressurized in...
Patent
1997-03-24
1998-10-27
Nguyen, Hoang
Motors: expansible chamber type
With motive fluid valve
Inlet fluid supplemented by controlled fluid pressurized in...
91420, 91437, 60460, F15B 1108
Patent
active
058264868
ABSTRACT:
Cylinder drift resulting from internal leakage of a recycling circuit, which recycles oil returned from the arm cylinder of a hydraulic shovel to the hydraulic supplying end, is reduced by an hydraulic circuit which includes a recycle valve attached directly to a control valve. When working fluid is returned from a rod chamber of arm cylinder into the control valve, the recycle valve recycles a part of the working fluid through a recycle selector valve to the hydraulic supplying end. A pilot operated check valve is disposed in the oil channel that connects the rod chamber and recycle selector valve together. When extending arm cylinder of the hydraulic shovel, pilot pressure from control valve shifts a pilot selector valve in such a direction as to open pilot operated check valve. When control valve is at the neutral position, pilot selector valve is shifted back to the return position and closes pilot operated check valve so that return oil of arm cylinder is prevented from working on recycle selector valve. Thus, internal leakage of recycle selector valve is prevented.
REFERENCES:
patent: 4216706 (1980-08-01), Brundidge
patent: 4509405 (1985-04-01), Bates
patent: 4531449 (1985-07-01), Reith
patent: 4624445 (1986-11-01), Putnam
patent: 4727792 (1988-03-01), Haussler
patent: 4732076 (1988-03-01), Ewald
Nguyen Hoang
Shin Caterpillar Mitsubishi Ltd.
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