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. 28, 1995
Filed:
Feb. 25, 1994
Douglas M Durant, Waterloo, IA (US);
Deere & Company, Moline, IL (US);
Abstract
Left and right two stage brake valves communicate fluid pressure to left and right brake mechanisms. Each brake valve has an inlet for receiving pressurized brake fluid from a pump, a reservoir port, a stepped bore and a stepped piston member comprising a larger diameter prefill piston and a smaller diameter high pressure piston. The stepped piston is movable away from a rest position to transfer fluid to the brake mechanism. The stepped bore and the stepped piston form a high volume prefill chamber and a high pressure chamber. The high pressure piston has a groove communicated with the brake mechanism, and the groove communicates with the inlet when the high pressure piston has moved a certain distance to transfer fluid from the high pressure chamber to the brake mechanism. The prefill piston has a sealing land and a second land on either side of a sealing ring which is slidable in the stepped bore. The sealing land sealingly engages the sealing ring when the prefill piston moves to transfer fluid from the prefill chamber to the brake mechanism. The sealing land is spaced apart from the sealing ring by a distance which is greater than the distance between the groove and the inlet when the stepped piston is in its rest position.