Abstract: A spool valve includes a valve block; a first spool, which is mounted onto one side on the inside of the valve block so as to be moved forward and backward in the lengthwise direction and includes a first notch formed on the outer circumferential surface, for controlling the connection between a first pump flow path and a first cylinder flow path through the first notch which is aligned with the first pomp flow path and the first cylinder flow path formed on the inside of the valve block, when moved according to a change in stroke; and a second spool, which is mounted onto the other side on the inside of the valve block so as to be moved forward and backward in the lengthwise direction and includes a second notch formed on the outer circumferential surface, for controlling the connection between a second cylinder flow path and a first tank flow path through the second notch which is aligned with the second cylinder flow path and the first tank flow path formed on the inside of the valve block, when moved acco

Abstract: A flow control valve for a construction machine includes a boom valve block connected to a hydraulic pump; a boom spool coupled to the boom valve block so as to be slidably moved, and switched on by the supply of pilot signal pressure in order to carry out a boom-up or boom-down operation, thereby controlling the hydraulic oil supplied from the hydraulic pump to a boom cylinder; a boom-up flow control arrangement for supplying the hydraulic oil from the hydraulic pump to the large chamber of the boom cylinder through the boom spool, when switching on the boom spool in order to carry out the boom-up operation; and a boom-down flow control arrangement for returning a part of the hydraulic oil, which returns from the large chamber of the boom cylinder, to the hydraulic tank through the boom spool only at a predetermined pressure or higher, when the boom spool is switched on in order to carry out the boom-down operation, wherein the part of the hydraulic oil, which returns from the large chamber of the boom cylin

Abstract: A spool valve includes a valve block; a first spool, which is mounted onto one side on the inside of the valve block so as to be moved forward and backward in the lengthwise direction and includes a first notch formed on the outer circumferential surface, for controlling the connection between a first pump flow path and a first cylinder flow path through the first notch which is aligned with the first pomp flow path and the first cylinder flow path formed on the inside of the valve block, when moved according to a change in stroke; and a second spool, which is mounted onto the other side on the inside of the valve block so as to be moved forward and backward in the lengthwise direction and includes a second notch formed on the outer circumferential surface, for controlling the connection between a second cylinder flow path and a first tank flow path through the second notch which is aligned with the second cylinder flow path and the first tank flow path formed on the inside of the valve block, when moved acco

Abstract: A flow control valve for a construction machine includes a boom valve block connected lo a hydraulic pump; a boom spool coupled to the boom valve block so as to be slidably moved, and switched on by the supply of pilot signal pressure in order to carry out a boom-up or boom-down operation, thereby controlling the hydraulic oil supplied from the hydraulic pump to a boom cylinder; a boom-up flow control arrangement for supplying the hydraulic oil from the hydraulic pump to the large chamber of the boom cylinder through the boom spool, when switching on the boom spool in order to carry out the boom-up operation; and a boom-down flow control arrangement for returning a part of the hydraulic oil, which returns from the large chamber of the boom cylinder, to the hydraulic tank through the boom spool only at a predetermined pressure or higher, when the boom spool is switched on in order to carry out the boom-down operation, wherein the part of the hydraulic oil, which returns from the large chamber of the boom cylin

Abstract: A construction machine float valve is disclosed, which can remove a spool stick phenomenon that may occur during leveling and flattening work.

Abstract: The present invention relates to a holding valve that is used for a hydraulic circuit for controlling a working device actuator of construction equipment, and to a holding valve for construction equipment in which a double nut and a sleeve are removed such that an assembling efficiency is improved and the cost is reduced, and further, the abnormal assembling of a piston can be prevented.