Abstract: A fluid pressure control device includes a neutral passage, a control valve provided in the neutral passage, a first supply passage, and a discharge passage, the control valve has, a switching valve configured to control a flow of a working fluid to the discharge passage from the first actuator in accordance with a pressure in a pilot chamber to which a part of the working fluid supplied from the first supply passage to the first actuator is led, and a throttle portion configured to throttle the flow of the working fluid supplied to the first actuator from the first supply passage, and the pressure on an upstream side of the throttle portion is led to the pilot chamber.

Abstract: A valve device includes a relief valve configured to be opened when a pressure in a fluid pressure circuit reaches a predetermined pressure and to relieve a working fluid, a tank passage connected to a tank, a main relief passage connecting the relief valve and the tank passage, and a sub relief passage branching from the main relief passage and connected to the tank passage separately from the main relief passage.

Abstract: A control valve includes a housing formed with first and second supply ports, first and second actuator ports, and a pilot port, and a spool accommodated slidably in the housing, and the spool is configured to allow the first supply port and the pilot port to communicate with each other both at the first communication position and the second communication position.

Abstract: A fluid pressure control device includes a switching valve, a main pilot passage and a sub pilot passage, the switching valve is configured to be switched to the open position when the working fluid is supplied to the pilot chamber, and to be switched to the throttled position with opening on the downstream side of the switching valve in the neutral passage, and the sub pilot passage is provided with a throttle portion and a check valve in parallel in the throttle portion.

Abstract: A fluid pressure control device includes a neutral passage, a control valve provided in the neutral passage, a first supply passage, and a discharge passage, the control valve has, a switching valve configured to control a flow of a working fluid to the discharge passage from the first actuator in accordance with a pressure in a pilot chamber to which a part of the working fluid supplied from the first supply passage to the first actuator is led, and a throttle portion configured to throttle the flow of the working fluid supplied to the first actuator from the first supply passage, and the pressure on an upstream side of the throttle portion is led to the pilot chamber.

Abstract: A fluid pressure control device includes a switching valve, a main pilot passage and a sub pilot passage, the switching valve is configured to be switched to the communication position when the working fluid is supplied to the pilot chamber, and to be switched to the shut-off position with opening on the downstream side of the switching valve in the neutral passage, and the switching valve has a throttle portion configured to throttle the flow of the working fluid in the neutral passage at the communication position.

Abstract: A valve device includes a relief valve configured to be opened when a pressure in a fluid pressure circuit reaches a predetermined pressure and to relieve a working fluid, a tank passage connected to a tank, a main relief passage connecting the relief valve and the tank passage, and a sub relief passage branching from the main relief passage and connected to the tank passage separately from the main relief passage.

Abstract: A fluid pressure control device includes a switching valve, a main pilot passage and a sub pilot passage, the switching valve is configured to be switched to the open position when the working fluid is supplied to the pilot chamber, and to be switched to the throttled position with opening on the downstream side of the switching valve in the neutral passage, and the sub pilot passage is provided with a throttle portion and a check valve in parallel in the throttle portion.

Abstract: A pilot type switching valve includes: a housing bore formed in a valve body, the housing bore having an opening end; a spool slidably housed in the housing bore, the spool being configured to allow or block a flow of the working fluid to a first relief valve; a pilot chamber to which pilot pressure biasing the spool in the valve opening direction is guided; and a spring configured to bias the spool in the valve closing direction. The spool has a bottom surface on which the pilot pressure acts in such a manner that the spool is biased in the valve opening direction, and the area of the bottom surface is smaller than the sectional area of the housing bore.

Abstract: A control valve includes a housing formed with first and second supply ports, first and second actuator ports, and a pilot port, and a spool accommodated slidably in the housing, and the spool is configured to allow the first supply port and the pilot port to communicate with each other both at the first communication position and the second communication position.

Abstract: A fluid pressure control device includes a switching valve that has a pilot chamber to which the working oil is supplied from the supply passage through the second control valve, and a first relief valve that is provided on the downstream side of the switching valve. The second control valve allows supply of the working oil to the pilot chamber in a case where a flow of the working oil to a tilt cylinder is allowed, and blocks the supply of the working oil to the pilot chamber in a case where the flow of the working oil to the tilt cylinder is blocked. The switching valve allows a flow of the working oil to the first relief valve in a case where the working oil is supplied to the pilot chamber, and blocks the flow of the working oil to the first relief valve in a case where the supply of the working oil to the pilot chamber is blocked.

Abstract: An electromagnetic pressure reducing valve includes a spool valve configured to allow or shut off communication between a pilot passage and a pilot pressure supply passage and a solenoid configured to give a thrust according to an intensity of a supplied electric current to the spool valve. The spool valve has a pressure receiving surface configured to generate a thrust in a direction opposite to the thrust by the solenoid by action of a pressure of a pilot pressure supply passage, and an area of the pressure receiving surface is set smaller than a cross sectional area of the spool valve.

Abstract: A compensator spool of a load sensing valve device includes a pressure chamber, a compensator throttle portion, a pressure introduction chamber, a pressure introduction port, a maximum load pressure introduction chamber, and a selector valve. A groove is formed around the pressure introduction port, and a groove moves relatively between a passage communicating with an actuator to reduce an opening area of the pressure introduction port when the compensator spool moves.

Abstract: A pilot type switching valve includes: a housing bore formed in a valve body, the housing bore having an opening end; a spool slidably housed in the housing bore, the spool being configured to allow or block a flow of the working fluid to a first relief valve; a pilot chamber to which pilot pressure biasing the spool in the valve opening direction is guided; and a spring configured to bias the spool in the valve closing direction. The spool has a bottom surface on which the pilot pressure acts in such a manner that the spool is biased in the valve opening direction, and the area of the bottom surface is smaller than the sectional area of the housing bore.

Abstract: A control valve device includes a valve body having an actuator port connected to an actuator and a relief passage configured to allow the actuator port to communicate with a return passage, a spool slidably assembled into the valve body and configured to allow the actuator port to selectively communicate with a supply side or a return side, a relief valve configured to open/close the relief passage to control pressure of the actuator port, and an on/off valve assembled into an assembling hole which is formed in the valve body. The on/off valve configured to allow the actuator port to communicate with the relief passage through the assembling hole at the time of valve open.

Abstract: A back-pressure control valve includes: a switching valve configured to open and close the connecting passage; and an emergency operation valve provided in the branch passage, the emergency operation valve being configured to open and close the branch passage by being operated manually. The emergency operation valve has a valve main body and a valve body. The valve body includes: the main body portion having the screw portion threaded into the valve main body; and the seat portion formed on the tip end of the main body portion, the seat portion being configured to open and close the branch passage by being seated on and separated from the valve seat provided in the accommodating hole.

Abstract: A compensator spool of a load sensing valve device has a pressure chamber, a compensator throttle portion, a pressure introduction chamber, a pressure introduction port, a maximum load pressure introduction chamber, and a selector valve. A groove is formed around the pressure introduction port, and a groove moves relatively to a passage communicating with an actuator so as to reduce an area of an opening of the pressure introduction port when the compensator spool moves.

Abstract: A pump discharge amount is divided in accordance with switch amounts of respective switch valves by leading load pressures of actuators to which compensator valves are connected to respective first pressure chambers of the compensator valves, leading a maximum load pressure selected by a selection unit to respective second pressure chambers of the compensator valves, and controlling respective openings of the compensator valves in accordance with respective pressure actions between the respective pressure chambers. A drain passage is provided to connect the first pressure chamber of the compensator valve to a tank, and a flow dividing ratio modification valve is provided to control a pressure in the first pressure chamber.

Abstract: A fluid pressure control device includes a switching valve that has a pilot chamber to which the working oil is supplied from the supply passage through the second control valve, and a first relief valve that is provided on the downstream side of the switching valve. The second control valve allows supply of the working oil to the pilot chamber in a case where a flow of the working oil to a tilt cylinder is allowed, and blocks the supply of the working oil to the pilot chamber in a case where the flow of the working oil to the tilt cylinder is blocked. The switching valve allows a flow of the working oil to the first relief valve in a case where the working oil is supplied to the pilot chamber, and blocks the flow of the working oil to the first relief valve in a case where the supply of the working oil to the pilot chamber is blocked.

Abstract: A switching valve includes a spool, a first cylinder port that communicates with the piston side chamber, a second cylinder port that communicates with the rod side chamber, a bridge passage having a first opening which is adjacent to the first cylinder port and a second opening which is adjacent to the second cylinder port, a regeneration passage formed in the spool to connect the second cylinder port communicating with the rod side chamber to the first cylinder port in accordance with a switching position of the spool, and a first communication port and a second communication port formed in the spool to communicate with the regeneration passage. The first communication port communicates with the second opening of the bridge passage, which is adjacent to the second cylinder port, and the second communication port communicates with the second cylinder port in accordance with the switching position of the spool.