Abstract: A control valve having a regeneration function, including a hollow valve body, a plurality of spaced ports provided at the valve body, the ports including a pump port, an actuator port, a regeneration port and a tank port, a hollow main spool movably disposed in the valve body, a regeneration spool movably disposed in the main spool and adapted to be moved by a flow of fluid delivered from a pump through the pump port, a fluid passage provided at the main spool and adapted to communicate the actuator port and the tank port together, the fluid passage being opened or closed by the movement of the regeneration spool, whereby as the regeneration spool is moved by the fluid flow delivered from the pump, a part, to be fed to the tank port, of a flow of fluid emerging from the actuator port is increased, while a part to be fed to the regeneration port is correspondingly decreased.

Abstract: In a hydraulic device including at least two actuators both adapted to be operated by a single pump, one of the actuators having priority over the other actuator, a control valve for the one actuator including a load hold check valve adapted to assign a variable priority function to the one actuator over the other actuator, the load hold check valve including a valve body provided with a pair of ports respectively communicating with the actuators and a parallel fluid passage communicating with the pump, the parallel fluid passage also communicating with a selected actuator port in an opened state thereof, a poppet disposed in the valve body and adapted to fully open the parallel fluid passage at a full stroke thereof and partially opening the parallel fluid passage at a limited stroke thereof, and a pressure setting spring adapted to always urge the poppet toward the initial position for closing the parallel fluid passage.

Abstract: An improved mono-block control valve having a side bypass passage substituting for a typical center bypass passage is disclosed. The side bypass passage simplifies the passage structure of the valve body into a two-dimensional structure, thereby remarkably reducing the valve body size and improving the space efficiency and cutting down the cost. The left and right return passes are connected together by a connection passage at every section of the valve body. Due to the connections passages, the control valve prevents passage resistance and pressure loss in the return passages and makes both the negative pressures in the right and left actuator ports and the negative pressures in the sections uniform. The control valve thus improves the operational stability and reliability.

Abstract: A holding check control valve including a main valve, an assistant valve, a check valve installed in an actuator fluid passage provided at the main valve and provided with a spring chamber, the check valve being adapted to be switched between an opened state for opening the actuator fluid passage and a closed state for closing the actuator fluid passage in response to a pressure difference between the actuator fluid passage and the spring chamber so that the return oil in the actuator fluid passage is returned via a return fluid line provided at the main valve at the opened state, a pair of spaced seat members fixedly disposed in the assistant valve, a hydraulic chamber defined between the seat members, the hydraulic chamber communicating with the spring chamber of the check valve, a plunger extending through the seat members, the plunger being slidable along the seat members between a position closing the hydraulic chamber and a position opening the hydraulic chamber, a pressure setting spring for exerting i