Power plants – Pressure fluid source and motor – With control means for structure storing work driving energy
Patent
1974-12-30
1976-05-18
Geoghegan, Edgar W.
Power plants
Pressure fluid source and motor
With control means for structure storing work driving energy
60414, 60418, 60484, 60DIG2, 91420, F15B 102, F15B 1116
Patent
active
039568911
ABSTRACT:
A closed center hydraulic system is provided for a lift truck which includes an accumulator, a motor driven pump for supplying fluid under pressure to the accumulator, a plurality of closed center proportional electrohydraulic control valves for a plurality of hydraulically operated devices on the truck such as the lift jack, the mast tilt jack and the hydraulic powered steering mechanism. The pressure to the steering control valve is reduced by a pressure reducing valve and the pressure fluid supply circuit from the accumulator to the lift and tilt circuits is controlled by a blocking valve which is opened when the manual control member for either the lift or tilt control valve is moved from neutral to an operating position. Initial movement of either manual control member causes the blocking valve to open and further movement meters flow, thus permitting the operator to regulate lift and tilt speeds. A return line interconnects the lift jack and reservoir in bypassing relation to the lift control valve and a pilot operated bypass valve in the return line has its pilot line connected to one of the lift control valve delivery ports. An energy recovery system is disclosed in the return line from the lift jack.
REFERENCES:
patent: 2674092 (1954-04-01), Gardiner
patent: 2841960 (1958-07-01), Holan et al.
patent: 2984985 (1961-05-01), MacMillin
patent: 3071926 (1963-01-01), Olson et al.
Allis-Chalmers Corporation
Geoghegan Edgar W.
Schwab Charles L.
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