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. 23, 1982
Filed:
Nov. 16, 1979
Orcenith D McWilliams, Morris, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
A hydraulic system (9) includes a hydraulic motor (10), a main control valve (17) for controlling said motor (10), a make-up valve (78,79) operatively associated with said main control valve (17) and a vent line (93,94,95,99) for selectively venting said make-up valve (78,79). In such hydraulic systems, and in particular, in prior art hydraulic systems used to raise and lower a load, there is always the possibility that should hydraulic pressure not be maintained in the vent line the make-up valve could come open and the load could unexpectedly move. Such a situation could occur with, for example, air trapped in said vent line and the simultaneous failure of a pump of the system. The present invention solves this problem by providing pressure maintaining arrangement (200) in fluid communication with said vent line (93,94,95,99). The pressure maintaining arrangement (200) insures that any air trapped in the vent line (93,94,95,99) will be compressed to maintain the pressure in the vent line (93,94,95,99) at a predetermined level. Thus, should the hydraulic pump (13,26) be inoperative, a load will not unexpectedly move due to the compression of air trapped in said vent line (93,94,95,99).