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:
Jan. 03, 1978
Filed:
Mar. 16, 1977
Lowell R Hall, Elwood, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
A fluid control valve includes a valve body having a pump inlet port and a drain outlet port and is of a construction sufficient for connecting the pump inlet port to a relatively high pressure pump and the drain outlet port to a substantially atmospheric pressure reservoir. A valve spool has a metering slot leading from the peripheral surface of a first land to a peripheral surface of a second land, the metering slot including a substantially cylindrical pocket recessed into the second land, and a groove formed in the first land and a reduced diameter portion positioned between the lands. The groove connects the peripheral surface of the first land with the cylindrical pocket and has an arcuate surface portion leading from the peripheral surface of the first land and an elongated bottom surface positioned substantially parallel to the longitudinal axis of the spool and tangent to the arcuate surface portion. The spool is movable along its longitudinal axis between a first position at which flow from the pump inlet port to the drain outlet port is metered outwardly relative to the spool through the cylindrical pocket and a second position at which fluid flow from the pump inlet port to the drain outlet port is metered inwardly through the groove. The metering slot is of a construction sufficient for directing the fluid metered inwardly through the groove into the cylindrical pocket to generate a force acting on the spool tending to close the metering slot.