The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 29, 1992
Filed:
Mar. 07, 1991
Clayton A Melrose, Oakes, ND (US);
Town & Country Research & Development, Inc., Marion, ND (US);
Abstract
A four-way hydraulic control valve automatically reverses flow of hydraulic fluid to a double acting hydraulic cylinder or to a reversible hydraulic motor when a substantial resistance to fluid flow is encountered, such as when the cylinder or a machine being operated by the cylinder or motor reaches a mechanical limit of its motion. The valve has a reciprocating spool in a valve body with two internal control valves, one at each end, and with appropriate internal pressure shunts for directing high pressure fluid into the control valves and drain fluid restrictions to shuttle the spool back and forth in response to an increase in pressure resulting from a substantial resistance to fluid flow.