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:
Mar. 18, 1997
Filed:
Dec. 13, 1995
Steven C Bray, Peoria, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
A two-stage electrohydraulic pressure control valve modulatably controls engagement of a spring applied, pressure released brake when electrical power directed thereto is suddenly lost. The control valve includes a shutdown valve mechanism between a pilot stage and a main stage to controllably reduce the fluid pressure in an accumulator storage chamber in three distinct stages. The first stage is the immediate blocking of fluid flow from the storage chamber by a flow control valve when fluid passing therethrough in one direction exceeds a predetermined flow rate. The second stage is reducing the fluid pressure in the storage chamber to a predetermined level by a relief valve when the flow control valve is in its flow blocking position. The third stage is accomplished by restricting fluid flow from the storage chamber at a predetermined flow rate through an orifice so that the main stage modulatably controls the reduction of fluid pressure in the brake chamber.