Patent Number: 6,253,658

Title: Hydraulic control system

Abstract: The invention provides a hydraulic control system capable of preventing an objective from crashing even if a load supporting passage is fractured or the like during a crane operation for moving down the objective with a hydraulic shovel. When a pilot pressure for switching a control valve 2 to a downward position b is less than a predetermined value, only first selector means switches, and when the pilot pressure exceeds the predetermined value, second selector means as well as the first selector means switches.

Inventors: Kimura; Jun (Kani-gun, JP)

Assignee: Kayaba Industry Co., Ltd.

International Classification: E02F 9/22 (20060101); F15B 11/00 (20060101); F15B 11/044 (20060101); F15B 20/00 (20060101); F15B 011/08 (); F15B 013/04 ()

Expiration Date: 07/03/2018