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:
Nov. 27, 1990
Filed:
Nov. 01, 1989
John M Graham, San Mateo, CA (US);
Other;
Abstract
A dual pressure vehicle air brake system (60, 61, 100, 101) made according to the invention includes first and second sources (62, 64) of pressurized air at, for example, 175 psi and 100 psi, respectively. A combination brake actuator (6) includes a conventional service brake chamber (8) adapted to accommodate the lower, second air pressure while the spring brake chamber (10) is made to accommodate the higher, first pressure. The use of the higher first pressure allows a stiffer actuator spring to be used and be fully deflected by the first pressure without substantially changing actuator piston areas and other elements of conventional combination brake actuators. A conventional modulated spring brake control valve (78) is used to supply air at the first pressure to the spring brake chamber. The service brake chamber is supplied with air at the second pressure through the outlet of a conventional service brake application valve (68). Compounding of brake forces, which could occur if both the service and spring brakes were applied simultaneously, may be reduced or eliminated using a conventional two-way check valve (50 ) or a novel shut off valve (102).