Patent ID: 6971302

Claim:
In a hydraulic circuit for an option apparatus of heavy equipment that includes a variable displacement hydraulic pump and a pilot pump, a work apparatus and an option apparatus connected with the hydraulic pump, a main control valve installed at a flow path between the hydraulic pump and the work apparatus and option apparatus for thereby controlling a flow direction of an working oil, a first electromagnetic proportion reducing valve for variably controlling a discharge flowrate of the hydraulic pump in response to an electric signal from a controller, and a remote control valve that controls a signal pressure capable of switching a spool of the main control valve, a hydraulic circuit for an option apparatus of heavy equipment using a boom confluence spool, comprising: a poppet valve installed at a flow path of a supply side of a spool for the option apparatus wherein said poppet valve is opened and closed; a boom confluence spool that is switched when a pilot signal pressure is supplied and controls the flowrate supplied to the option apparatus and work apparatus and is installed at a direct upstream of the spool of the option apparatus; a second electromagnetic proportion reducing valve that is installed at a flow path between the pilot pump and the boom confluence spool and outputs a secondary pressure in response to an electric signal from the controller and controls a stroke of the boom confluence spool; and a first spool that is installed at a downstream of the poppet valve and is switched when a pressure difference between upstream and downstream of the boom confluence spool is larger than a set value and has a function capable of decreasing an opening degree of the poppet valve.