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.

Date of Patent:
Feb. 03, 1981

Filed:

Sep. 24, 1979
Applicant:
Inventors:

Kazuo Uehara, Tokyo, JP;

Hideaki Tohma, Yokohama, JP;

Yoshito Sato, Hirakata, JP;

Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F04B / ;
U.S. Cl.
CPC ...
417216 ; 60447 ; 60486 ;
Abstract

A hydraulic control system for variable displacement pumps, comprising at least two variable displacement pumps, a prime mover for driving the variable displacement pumps, a fixed displacement pilot pump driven by the common prime mover, a pressure compensating valve comprising a two-stage proportional pressure reducing valve and a negative proportional pressure reducing valve, the pressure compensating valve being connected to the variable displacement pumps and the fixed displacement pilot pump, and at least two servo boosters each being mechanically connected to the respective variable displacement pumps for controlling the displacement therefrom, the servo boosters being connected to the fixed displacement pilot pump and the pressure compensating valve and controlled thereby.


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