Importance

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Abstract

The invention contemplates hydraulic-lift mechanism which employs a power integrator in the connection between a charged hydraulic accumulator and the actuator for a vertically positionable load; the power integrator, additionally, has a prime-mover connection, and the pressurized charge of the accumulator is advisedly set to fully accommodate a preselected level of average load upon the actuator. The hydraulic circuit importantly includes check valves, with a pilot-operated check valve interposed between the power integrator and the accumulator and another pilot-operated check valve interposed between the power integrator and the load actuator. The pilot-operated check valves cooperate with other check valves to assure automatic transfer of hydraulic fluid under pressure from the accumulator to the load actuator, and vice versa, as may be determined by selected control of or via the power integrator. The system of check valves also cooperates with pump action to assure that adequate fluid is drawn from a sump and is deliverable for pilot-operated functions; stated in other words, with minimum reliance upon the sump, the system provides maximum conservation of energy in effecting such transfer of pressurized fluid, from and to the accumulator, as may be involved in any controlled lift or descent of any load, within the capacity of the system.

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First Claim