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:
Aug. 07, 1990
Filed:
Jun. 26, 1989
John R Coleman, Dayton, OH (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A master cylinder having pistons sliding through high pressure lip seals during operation. When the pistons are at rest during release, the seals are in an open position relative to the pistons sufficient to permit the passage of fluid therepast for compensation. The open positions are attained by providing piston portions of smaller diameter than the high pressure seals. These piston portions may be at least parts of piston beveled edge surfaces, or such edge surfaces in conjunction with notches or grooves which are of smaller diameter than the high pressure lip seals. The notches or grooves may extend circumferentially completely around the pistons, or may be arcuately extending circumferentially spaced notches or grooves.