Patent ID: 7478531

Claim:
A hydraulic circuit for a heavy construction equipment, comprising: a work control valve which controls a working apparatus cylinder by supplying or retrieving a hydraulic fluid of a first hydraulic pump through a work unit flow path; a confluence valve which is installed at a parallel flow path connected with a second hydraulic pump and combines a hydraulic fluid of the second hydraulic pump with the work unit flow path based on a positions switch; a swing control valve which is installed at the parallel flow path and controls a swing apparatus by supplying or retrieving a hydraulic fluid of the second hydraulic pump to a plurality of hydraulic swing motors which drive the swing apparatus; and a disconnection valve which is installed at a swing flow path connecting the swing control valve and at least one of the swing motors and is position-switched when the confluence valve is position-switched for thereby disconnecting the hydraulic fluid supplied to at least one of the swing motors and at the same time communicating an inlet and an outlet of the disconnected swing motor.