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:
May. 04, 1982
Filed:
Mar. 04, 1980
Donald L Bianchetta, Coal City, IL (US);
Sammy J Rhodes, Aurora, IL (US);
Caterpillar Tractor Co., Peoria, IL (US);
Abstract
An improvement is disclosed in a hydraulic system (10) having a variable displacement pump (12) and being capable of delivering pressurized fluid from the pump (12) to selectively engage at least three work circuits (18) with a first (20) of the circuits (18) being normally operable up to a first pressure and a second (22) of the circuits (18) being normally operable up to a second and lower pressure. The improvement comprises circuitry (80, 92, 94, 98, 108, 120, 122, 124, 126) for selectively operating a third (24) of the circuits (18) at one of the first or second pressures or at an upstaged pressure which exceeds the first pressure and circuitry (128) for reducing the displacement of the pump (12) in response to the third circuit (24) being operated at the upstaged pressure. Such upstaged pressure is available in a controlled manner for working against particularly heavy loads. Thus, a third and higher operating level is added to a system which already operates at at least two pressure levels.