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. 03, 1981
Filed:
Oct. 29, 1979
Lawrance F Berg, Lockport, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
PCT No. PCT/US79/00920 Sec. 371 Date Oct. 29, 1979 Sec. 102(e) Date Oct. 29, 1979 PCT Filed Oct. 29, 1979 A steering system (36) for vehicles (10) in which a device (90) is provided for circulating fluid through the system when operating in a cold environment. The system includes a hand metering unit (58) which is connected to opposite ends of a pilot operated steering valve (42) through a pair of pilot lines (60,62). A pressure reducing valve (94) maintains a continuous flow of fluid to the pilot lines (60,62) at a first predetermined pressure level. A pressure responsive valve (94) positioned between the hand metering unit (58) and a reservoir (40) intermittently passes pilot control fluid, returned to the hand metering unit (58) from the pilot actuation of the steering valve (42), to the reservoir (40) in response to the pressure of such returned fluid reaching a second slightly higher predetermined pressure level such as occurs when the fluid in the system is cold. This passing of cold fluid to the reservoir and the subsequent replacement of such fluid establishes circulation of fluid through the pilot control system and overcomes the problems of increased operator input force and increased system response time caused by cold fluid in the pilot control system.