Abstract: Provided is a hydraulic circuit of construction equipment, including a boom cylinder for controlling ascending and descending movement of a boom, which includes a valve unit having a first control valve configured to control a large chamber of the boom cylinder to selectively communicate with a small chamber of the boom cylinder, a second control valve configured to control the large chamber to selectively communicate with an oil tank, a third control valve configured to control the large chamber to selectively communicate with an accumulator, and a fourth control valve configured to control a part of hydraulic oil flowing to the accumulator to selectively flow to an assist motor.

Abstract: Provided is a hydraulic circuit of construction equipment, including a boom cylinder for controlling ascending and descending movement of a boom, which includes a valve unit having a first control valve configured to control a large chamber of the boom cylinder to selectively communicate with a small chamber of the boom cylinder, a second control valve configured to control the large chamber to selectively communicate with an oil tank, a third control valve configured to control the large chamber to selectively communicate with an accumulator, and a fourth control valve configured to control a part of hydraulic oil flowing to the accumulator to selectively flow to an assist motor.

Abstract: A control valve is provided for construction equipment having a holding valve which prevents the natural lowering of an operation apparatus due to the dead weight of the operation apparatus when an actuator is in a neutral position. The control valve includes a valve body, a spool, a holding valve, a control valve, and a pilot pressure control valve. The control valve can save manufacturing cost as well as allow better use of space for construction equipment.

Abstract: Disclosed is a hydraulic circuit for construction equipment, having a floating function for ground leveling work, which can be implemented by a main control valve.

Abstract: A control valve is provided for construction equipment having a holding valve which prevents the natural lowering of an operation apparatus due to the dead weight of the operation apparatus when an actuator is in a neutral position.

Abstract: The present invention relates to a hydraulic control valve for construction machinery that is used to maintain secondary pilot pressure which is formed proportionally to the switching of a switching device so as to be equal to or below a setting pressure of a pilot pump.

Abstract: Disclosed is a hydraulic circuit for construction equipment, having a floating function for ground leveling work, which can be implemented by a main control valve.

Abstract: A flow control valve for a construction machine is disclosed, which enables a combined operation for simultaneously operating a working device, such as an arm, and a swing device to be easily performed by limiting a part of hydraulic fluid that is supplied to the working device side by a priority valve that is shifted simultaneously or releasing the limiting function through shifting of a spool of the priority valve to a neutral position by pilot signal pressure that is separately applied according to a type of work.

Abstract: A flow control valve for a construction machine is provided, which can constantly control a flow rate of hydraulic fluid supplied to a hydraulic actuator through a flow control spool in a spool. The flow control valve for a construction machine, having a valve body in which a supply passage communicating with a pump passage and actuator ports connected to a hydraulic actuator are formed, and a spool installed in the valve body to be shifted, includes a flow control spool shifted in the spool to variably control a cross-sectional area of a passage connected to the one actuator port if a flow rate of the hydraulic fluid that flows through the supply passage is higher than a set flow rate, a first passage formed on the spool to communicate with the supply passage and a second passage formed on the spool to communication with the one actuator port and having a cross-sectional area that is varied depending on the shifting of the flow control spool.

Abstract: The present invention relates to a hydraulic control valve for construction machinery that is used to maintain secondary pilot pressure which is formed proportionally to the switching of a switching device so as to be equal to or below a setting pressure of a pilot pump.

Abstract: A hydraulic control valve for a construction machine is disclosed, which can variably control the flow of hydraulic fluid that is supplied to a hydraulic cylinder to drive a working device. The hydraulic control valve for a construction machine includes a valve block in which an inlet port and an outlet port that communicates with the inlet port is formed, a check valve provided with a first throttling portion to permit the flow of the hydraulic fluid from the inlet port to the outlet port and to variably control the flow of the hydraulic fluid from the outlet port to the inlet port, and a spool provided with a second throttling portion to variably control the flow of the hydraulic fluid from the outlet port to the inlet port through the check valve that is opened when the second throttling portion is shifted by pilot signal pressure.

Abstract: A flow control valve for a construction machine is disclosed, which enables a combined operation for simultaneously operating a working device, such as an arm, and a swing device to be easily performed by limiting a part of hydraulic fluid that is supplied to the working device side by a priority valve that is shifted simultaneously or releasing the limiting function through shifting of a spool of the priority valve to a neutral position by pilot signal pressure that is separately applied according to a type of work.

Abstract: A flow control valve for a construction machine is provided, which can constantly control a flow rate of hydraulic fluid supplied to a hydraulic actuator through a flow control spool in a spool. The flow control valve for a construction machine, having a valve body in which a supply passage communicating with a pump passage and actuator ports connected to a hydraulic actuator are formed, and a spool installed in the valve body to be shifted, includes a flow control spool shifted in the spool to variably control a cross-sectional area of a passage connected to the one actuator port if a flow rate of the hydraulic fluid that flows through the supply passage is higher than a set flow rate, a first passage formed on the spool to communicate with the supply passage and a second passage formed on the spool to communication with the one actuator port and having a cross-sectional area that is varied depending on the shifting of the flow control spool.

Abstract: A hydraulic control valve is provided, which can prevent the occurrence of overload by relieving hydraulic fluid of a return line in which the overload occurs due to an inertial force of a rotator when a hydraulic motor that is operated by the hydraulic fluid supplied from a hydraulic pump stops halfway.

Abstract: A hydraulic control valve for a construction machine is disclosed, which can variably control the flow of hydraulic fluid that is supplied to a hydraulic cylinder to drive a working device. The hydraulic control valve for a construction machine includes a valve block in which an inlet port and an outlet port that communicates with the inlet port is formed, a check valve provided with a first throttling portion to permit the flow of the hydraulic fluid from the inlet port to the outlet port and to variably control the flow of the hydraulic fluid from the outlet port to the inlet port, and a spool provided with a second throttling portion to variably control the flow of the hydraulic fluid from the outlet port to the inlet port through the check valve that is opened when the second throttling portion is shifted by pilot signal pressure.

Abstract: A hydraulic control valve is provided, which can prevent the occurrence of overload by relieving hydraulic fluid of a return line in which the overload occurs due to an inertial force of a rotator when a hydraulic motor that is operated by the hydraulic fluid supplied from a hydraulic pump stops halfway.