HYDRAULIC CIRCUIT OF WORKING MACHINE

摘要

The present invention relates to a hydraulic circuit for a working machine which prevents decrease in the working speed of a clamshell bucket upon expansion of an expansion arm, so that improvement of the operability can be achieved. A hydraulic circuit for a working machine, which is configured such that a clamshell bucket (5) is attached to a tip end of an expansion arm (4) and the expansion arm (4) and the clamshell bucket (5) are operated by pressure oil supplied from a common pressure source (7a, 7b), includes pressure reduction means (20, 21) for reducing an operating pressure for driving the expansion arm (4) to the expansion side based on an operating pressure for opening the clamshell bucket (5). By the configuration, the clamshell bucket (5) can be opened rapidly, and improvement of the operability is achieved. <IMAGE>