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:
Jun. 18, 1996
Filed:
Mar. 31, 1995
C Nickolas Goloff, Secor, IL (US);
Caterpillar Inc., Peoria, IL (US);
Abstract
Many known all wheel steer arrangements suffer from the problem that the front and rear wheels getting out of synchronization due to leakage and/or inadvertent passing of fluid across the control valve arrangement therein. In the subject invention, a hydraulic system has front and rear pairs of steerable wheels respectively interconnected by first and second fluid cylinder arrangements. A steering control arrangement operatively controls the front and rear pairs of steerable wheels between a mode in which only the front pair of wheels are steered, a second mode in which both the front and rear pairs of wheels are simultaneously steered but in opposite directions, and a third mode in which the rear wheels are steered independently of the front pair of wheels. First, second and third poppet valve arrangements 50, 70, 82 are utilized to provide control for the various modes of operation and to provide separation of the fluid between the first and second cylinder arrangements used to steer the respective front and rear wheel assemblies. Back to back poppet valves are used in each of the first, second and third poppet valve arrangements to insure that when the respective poppet valve arrangements are in their closed flow blocking position, that no fluid flow is allowed to pass thereacross.