Electro-hydraulic quick drop circuit

Details Electro-hydraulic quick drop circuit Electro-hydraulic quick drop circuit

1992-12-14

1993-07-13

Look, Edward K.

Motors: expansible chamber type

With motive fluid valve

Inlet fluid supplemented by controlled fluid pressurized in...

91446, 91448, 91461, F15B 1108

Patent

active

052263487

ABSTRACT:
Quick drop valves are useful in directing fluid expelled from a contracting chamber of a hydraulic actuator to its expanding chamber under gravity load conditions. The present electro-hydraulic quick drop circuit improves the efficiency of the quick drop valve by energizing a solenoid valve to direct load generated pressure from the rod end chamber of the hydraulic actuators to an end of a quick drop valve for moving the quick drop valve to the quick drop position when a control valve is at or between a preselected intermediate operating position and its fully open position. The quick drop valve is moved to the quick drop position immediately upon the control valve reaching the preselected operating position so that the fluid expelled from the rod end chamber is directed to the head end chamber almost immediately after the blade begins to freefall. Also the quick drop valve totally blocks the rod end chambers from the control valve so that all the fluid expelled from the rod end chambers is directed to the head end chambers at the quick drop position of the quick drop valve.

REFERENCES:
patent: 3438307 (1969-04-01), Ahlenius
patent: 3568707 (1971-03-01), Shore
patent: 3965587 (1976-06-01), Johns, Jr.
patent: 4397221 (1983-08-01), Friesen et al.
patent: 4694647 (1987-09-01), Yoshida
patent: 4770083 (1988-09-01), Johnson
patent: 4955282 (1990-09-01), Ranson
patent: 5014734 (1991-05-01), Smith
patent: 5081904 (1992-01-01), Horn et al.

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