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:
Jul. 11, 1978
Filed:
Sep. 01, 1976
Joseph Edward Dezelan, Western Springs, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
A pilot-operated, spring-centered, directional control valve includes a valve body having a bore, chambers at opposite ends of the bore, a valve spool slidably disposed within the bore, a hollow piston slidably disposed within each of the chambers and biased by springs inwardly toward the spool, and a secondary piston slidably disposed within one of the primary pistons so that pilot pressure directed into the outward ends of the chambers acts on the end of the spool or the end of the secondary piston to selectively operate the valve. The various components of the valve have differing effective cross-sectional areas upon which pilot pressure acts. The control valve is advantageously employed in a hydraulic system controlling front wheel drive in a vehicle.