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:
Jun. 30, 1992

Filed:

Apr. 25, 1991
Applicant:
Inventors:

Kazuyoshi Arii, Sakai, JP;

Shiro Watanabe, Sakai, JP;

Kazuhiko Tsuji, Sakai, JP;

Assignee:

Kubota Corporation, Osaka, JP;

Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
F16D / ; F15B / ;
U.S. Cl.
CPC ...
60484 ; 91521 ; 91530 ; 13759615 ; 137635 ;
Abstract

A control change system for a hydraulic working vehicle having a plurality of hydraulic actuators operable by control levers each shiftable to a plurality of control positions. This system includes a plurality of pilot-operated control valves for controlling pressure oil supply to the hydraulic actuators, respectively, pilot pressure generating valves for generating a pilot pressure in accordance with the control positions of the control levers, and a pilot pressure switching unit for receiving the pilot pressure from the pilot pressure generating valves and outputting the pilot pressure selectively to the control valves. The pilot pressure switching unit includes a plurality of spools slidable to change communicating passages between a pilot pressure input section and a pilot pressure output section of the switching unit.


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