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:
Sep. 26, 1978
Filed:
Feb. 23, 1977
Otis A Johnston, League City, TX (US);
Western Geophysical Company of America, Houston, TX (US);
Abstract
A two-axle, four-wheel-drive vehicle has separate hydraulic drive systems to drive the front and rear pairs of traction wheels. Each drive system includes a hydraulic motor that is powered by its own variable displacement pump. The torque developed by the motors, and the hydrostatic drive pressure, depend on the volume of fluid flow from the pumps. Under certain conditions, the hydrostatic drive pressure to the two motors becomes unbalanced. A torque equalizer valve is interconnected between the two hydraulic drive systems. When the equalizer valve senses a hydrostatic drive pressure difference between the two drive systems, it readjusts the displacement of the pump having the higher pressure by lowering the hydrostatic pilot pressure to restore the balance of hydrostatic drive pressures.