HYDRAULIC SYSTEM FOR IMPROVING FLATTING WORKABILITY IN AN EXCAVATOR

摘要

Disclosed is a hydraulic system for an excavator, which is structurally improved so as to easily perform flatting work on a plain or inclined ground. A boom control valve has a fourth position on one side thereof such that a boom cylinder can be freely lifted and lowered by blocking a channel through which hydraulic operating fluid is supplied from a pump and by allowing hydraulic operating fluid inlet and outlet ports of the boom cylinder system to communicate with each other.