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:
Apr. 03, 1990
Filed:
Dec. 03, 1987
William L Callahan, Lafayette, IN (US);
Bruce C Noah, W. Lafayette, IN (US);
Jonathan B Kulp, Terre Hill, PA (US);
TRW Inc., Lyndhurst, OH (US);
Abstract
An apparatus is disclosed for controlling at least two driven wheels of a vehicle. The apparatus includes two hydraulic motors, each motor drivably connected to an associated drive wheel. A load sense piston pump provides a source of pressurized fluid for operating the hydraulic motors. Associated with each hydraulic motor is an electrically controllable load sense flow control valve assembly, an electrically controllable directional control valve, and a set of counterbalance valves. A microcomputer controls operation of the electrically controllable load sense flow control valve assemblies and the electrically controllable directional control valves in response to electrical signals indicative of rotary position of a steering wheel, position of an operator controlled speed and direction input device, and the speed of the vehicle engine. Steering ratio can be selected by the operator. Vehicle speed is controlled so as to prevent pump cavitation and engine stalling.