Abstract: Disclosed is a flow rate control valve for a construction machine. A flow rate control valve for a construction machine comprises: a valve body having a pump channel for receiving operating oil from a hydraulic pump, a supply channel connected to the pump channel, and an actuator port connected to a hydraulic actuator; a spool installed inside the valve body to be switchable such that, when switched in response to application of signal pressure, the spool selectively causes the supply channel and the actuator port to communicate with each other; a tank channel installed inside the valve body and connected to an operating oil tank; and an orifice formed in the spool to have an inlet formed on an end and an outlet communicating with the tank channel, wherein, when the spool is initially actuated, a part of the signal pressure is discharged to the operating oil tank via the orifice.

Abstract: A hydraulic pipe fixing apparatus for a boom-swing type excavator is disclosed, which makes hydraulic hoses for attachments and hydraulic hoses for additional option devices be arranged in predetermined positions inside a boom supporter (4).

Abstract: Disclosed is a brake device for braking front and rear axles by working oil supplied to front and rear brake cylinders from a hydraulic pump according to the control of a brake pedal.

Abstract: Disclosed is a hydraulic system for a construction machine, which makes it possible to adjust the geometric position of a working device comprising a boom and an arm by means of a single manipulation lever, thereby enabling a leveling/flattening process to be conveniently performed. The hydraulic system includes: a working mode selection switch for selecting a leveling/flattening process; a boom driving switch valve for controlling the driving of a boom cylinder in response to a control signal from a first manipulation lever; an arm driving switch valve for controlling the driving of an arm cylinder in response to a control signal from a second manipulation lever; a shuttle valve including input parts that connect to both an electronic proportional control valve and to the first manipulation lever, respectively, and an output part connecting to the boom driving switch valve; and an electronic controller.