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:
Oct. 01, 1991
Filed:
Mar. 16, 1990
Kazuhiko Fujii, Hiroshima, JP;
Kabushiki Kaisha Kobe Seiko Sho, Kobe, JP;
Abstract
Described herein is a hydraulic pump control circuit for travelling construction machine, the circuit being of the type including various hydraulic actuators divided into two groups to be driven by first and second pumps, respectively, left and right vehicle drive motors provided in the respective groups, and a change-over valve located on the discharge side of the first and second pumps and switchable to a position for supplying the oil pressure from the second pump in parallel to the left and right vehicle drive motors. According to the invention, the control circuit is provided with a pilot proportioning valve located between a discharge flow rate control regulator for the second pump and a pilot pressure source, and means for applying the pilot pressures acting on left and right vehicle drive valves to pilot ports of the pilot proportioning valve, the proportioning valve being operated by the sum of the pilot pressures applied to the pilot ports to produce a control pressure for the second pump regulator.