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:
Jun. 07, 1988
Filed:
Oct. 14, 1987
John M Graham, San Mateo, CA (US);
Other;
Abstract
A vehicle brake system includes a check valve having an input port coupled to a fluid pump outlet and an output port coupled to hydraulically deactuated spring brakes through brake lines. A pilot check valve has a pilot port, an inlet port coupled to the input port of the check valve and a return port coupled to the fluid reservoir. The pilot port is coupled to the output port of the check valve so the pilot check valve opens only when the output port is pressurized. This allows hydraulic fluid to flow from the pump, through the pilot check valve and to the reservoir. To set the brakes when stopped or in emergency situations the operator actuates a valve which dumps the fluid in the brake lines into the reservoir. A second pilot check valve has its pilot port connected to a brake pedal actuated master cyinder, its inlet connected to the brake line and its outlet connected to the reservoir. Pressing on the brake pedal connects the brake line to the reservoir through a variable restriction so to allow the spring brakes to be applied in the modulated manner of service brakes.