Hydraulic cylinder extension control
AssigneeClark Equipment Company
InventorsWillard L. Chichester, Donald A. Holtkamp
Life of this patent
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Abstract
A hydraulic circuit for operator pre-selection in one exemplary embodiment of the extension of a lift truck upright which utilizes a fixed displacement hydraulic motor operating to adjust either a rotary switch or a potentiometer which is connected to a valve for interrupting the flow to the lift cylinder of the upright at the pre-selected height. The adjusted position of an operator's lift height selector is coordinated with the rotary switch or potentiometer or to effect the selected extension of the upright.
Claims13
In a lift truck having an extensible hydraulic lift cylinder for elevating extensible lift upright means to pre-slected elevations and hydraulic pump and valve means for actuating and controlling elevation of the upright means, means operative to pre-select and control automatically the distance of extension of the upright means including means for measuring the hydraulic fluid volume flowing to the lift cylinder during extension thereof, operator control means for selecting the desired extension of the upright means, means operative to interrupt the flow of hydraulic fluid to the lift cylinder at said desired upright extension irrespective of cylinder pressure, and circuit means operatively connected to said operator control means, to said fluid volume measuring means and to said interrupter means.
A control system for an extensible hydraulic cylinder means having hydraulic pump and valve means for actuating and controlling the extension of the cylinder means, comprising means operative to pre-select and control automatically the distance of extension of the cylinder means including means for measuring the hydraulic fluid volume flowing to the cylinder means during extension thereof, operator control means for selecting the desired extension of the cylinder means, means operative to interrupt the flow of hydraulic fluid to the cylinder means at said desired extension irrespective of cylinder pressure, and circuit means operatively connected to said operator control means, to said fluid volume measuring means and to said interrupter means.
Dependencies are inferred from the claim text.