Hydraulic elevator and a control method thereof
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United States of America Patent
Stats
-
Feb 8, 1994
Grant Date -
N/A
app pub date -
Feb 28, 1992
filing date -
Feb 28, 1991
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A hydraulic elevator comprises a car, a hydraulic jack to drive the car, a hydraulic pump, and control means for controlling a flow rate of fluid flowing to or from the hydraulic jack thereby to control movement of the car. The control means comprises a main valve constructed so as to allow fluid the flow from the pump into the hydraulic jack when a pressure of the fluid is higher than a predetermined value thereby to effect upward running of the car, and to check a fluid flow from the hydraulic jack when the pressure of the fluid from the pump is less than the predetermined value, and valve control means including a plurality of pilot valves for controlling, when the pressure of the fluid from the pump is less than the value, the main valve to open and close, and wherein the valve control means controls the closing operation of the main valve along at least two different patterns.
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