Abstract: A blocking configuration of an oil pressure circuit hole includes a plug screwed together with an aperture end portion of the oil pressure circuit hole provided to a main body. The plug includes: a shaft portion; an external thread portion disposed on a leading end of the shaft portion; an O-ring mounted on an outer periphery of a base end portion of the shaft portion and pressed between the outer periphery of the shaft portion and an inner periphery of the oil pressure circuit hole to seal them; a flange portion having an external diameter larger than that of the shaft portion and disposed on a part of a base end side of a storage groove on which the O-ring is mounted; and a polygonal column-shaped head portion on which a tightening tool is mounted and disposed on a part of a base end side of the flange portion.

Abstract: A blocking configuration of an oil pressure circuit hole includes a plug screwed together with an aperture end portion of the oil pressure circuit hole provided to a main body. The plug includes: a shaft portion; an external thread portion disposed on a leading end of the shaft portion; an O-ring mounted on an outer periphery of a base end portion of the shaft portion and pressed between the outer periphery of the shaft portion and an inner periphery of the oil pressure circuit hole to seal them; a flange portion having an external diameter larger than that of the shaft portion and disposed on a part of a base end side of a storage groove on which the O-ring is mounted; and a polygonal column-shaped head portion on which a tightening tool is mounted and disposed on a part of a base end side of the flange portion.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. Communication between the lever electromagnetic control valve and the steering valve is allowed when only the lever electromagnetic control valve is operated.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, a pump that supplies operating fluid to the steering cylinder via the steering valve, and a return oil passage connected to a tank. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a throttle arranged in the return oil passage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a switching valve and a priority control valve switchable between a handle stage and a lever stage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, a pump that supplies operating fluid to the steering cylinder via the steering valve, and a return oil passage connected to a tank. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a throttle arranged in the return oil passage.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. Communication between the lever electromagnetic control valve and the steering valve is allowed when only the lever electromagnetic control valve is operated.

Abstract: A steering device for a wheel loader includes a handle for steering, a lever for steering, a steering cylinder, a steering valve that controls a direction of operating fluid to the steering cylinder, and a pump that supplies operating fluid to the steering cylinder via the steering valve. The steering device further includes a handle control valve that controls the supply direction of the operating fluid according the handle, a lever electromagnetic control valve that controls the supply direction of operating fluid according to the lever, and a handle prioritization valve that shuts off a pilot hydraulic pressure supplied from the lever electromagnetic control valve to the steering valve according to a pressure produced by operating fluid flowing through the handle control valve when the handle is operated. The handle prioritization valve includes a switching valve and a priority control valve switchable between a handle stage and a lever stage.

Abstract: A steering device for a wheel loader includes a rotatable handle, a tiltable lever, a steering cylinder, a steering valve, a pump, a handle control valve, a lever control valve, and a handle prioritization valve. The steering valve controls a supply direction of operating fluid to the steering cylinder with pilot hydraulic pressure. The pump supplies operating fluid to the steering cylinder via the steering valve. The handle and lever control valves supply pilot hydraulic pressure to control the supply direction to the steering valve according to handle rotation and lever tilt, respectively. The handle prioritization valve shuts off the pilot hydraulic pressure supplied from the lever control valve to the steering valve according to a differential pressure or an absolute pressure in a hydraulic circuit produced due to operating fluid flowing through the handle control valve when the handle is operated.

Abstract: An oil filter interposed in an oil passage and configured to perform filtering of oil by causing the oil to pass through a passage hole of a filter body formed by etching, wherein an oil passing section is etched to a half of plate thickness of the filter body on one surface of the filter body, and a plurality of the passage holes are formed by etching in a region where the oil passing section is formed on the other surface of the filter body.

Abstract: A hydraulic servo drive device includes: a pilot spool for switching supply and shutoff of oil; a servo piston slid in accordance with the pilot spool; a stroke sensor for detecting a displacement of the servo piston; a first hydraulic chamber in which oil for moving the servo piston is flowed; a first piston oil path for communicating a pump port to which oil is supplied from a pump with a first hydraulic chamber; and a discharge circulating oil path for communicating the first hydraulic chamber with a drain port.

Abstract: A steering device for a wheel loader includes a rotatable handle, a tiltable lever, a steering cylinder, a steering valve, a pump, a handle control valve, a lever control valve, and a handle prioritization valve. The steering valve controls a supply direction of operating fluid to the steering cylinder with pilot hydraulic pressure. The pump supplies operating fluid to the steering cylinder via the steering valve. The handle and lever control valves supply pilot hydraulic pressure to control the supply direction to the steering valve according to handle rotation and lever tilt, respectively. The handle prioritization valve shuts off the pilot hydraulic pressure supplied from the lever control valve to the steering valve according to a differential pressure or an absolute pressure in a hydraulic circuit produced due to operating fluid flowing through the handle control valve when the handle is operated.

Abstract: An electric lever device includes a detent mechanism 6 between the rotational center shaft 3 and the handgrip 2. The detent mechanism 6 includes a pressing unit 10 including a through hole 11 formed in an axis C1 direction of the operation lever 1, an extension coil spring 12 inserted into the through hole 11 and balls 13a and 13b provided on both ends of the extension coil spring 12 for generating pressing force in the axis C 1 direction, and a guide unit 20 for guiding movement in a circumferential direction of the axis C 1 and changing the pressing force by changing a guide width in the axis C1 direction to apply a load to the movement of the operation lever 1 together with pulling force of a twisted coil spring 30.

Abstract: An oil filter interposed in an oil passage and configured to perform filtering of oil by causing the oil to pass through a passage hole of a filter body formed by etching, wherein an oil passing section is etched to a half of plate thickness of the filter body on one surface of the filter body, and a plurality of the passage holes are formed by etching in a region where the oil passing section is formed on the other surface of the filter body.

Abstract: An electric lever device includes a detent mechanism 6 between the rotational center shaft 3 and the handgrip 2. The detent mechanism 6 includes a pressing unit 10 including a through hole 11 formed in an axis C1 direction of the operation lever 1, an extension coil spring 12 inserted into the through hole 11 and balls 13a and 13b provided on both ends of the extension coil spring 12 for generating pressing force in the axis C 1 direction, and a guide unit 20 for guiding movement in a circumferential direction of the axis C 1 and changing the pressing force by changing a guide width in the axis C1 direction to apply a load to the movement of the operation lever 1 together with pulling force of a twisted coil spring 30.

Abstract: In order to reduce hysteresis and other noise components included in the output signal characteristic of a differential pressure sensor, an elastic reaction member which operates together with a diaphragm provided in a chamber of the differential pressure sensor includes a contact portion which contacts the diaphragm, and a plurality of springs which are arranged symmetrically about the contact portion. Each of the springs is a plate shaped or linear shaped spring which is bent into the form of a letter C, U, J, or V, and has one of its ends fixed to a wall which defines the chamber, while its other end is connected to the contact portion. When the contact portion shifts together with the diaphragm, the deformations of the plurality of springs are mutually balanced, so that rotation and horizontal deviation of the contact portion with respect to the diaphragm is suppressed.

Abstract: A hydraulic servo drive device includes: a pilot spool for switching supply and shutoff of oil; a servo piston slid in accordance with the pilot spool; a stroke sensor for detecting a displacement of the servo piston; a first hydraulic chamber in which oil for moving the servo piston is flowed; a first piston oil path for communicating a pump port to which oil is supplied from a pump with a first hydraulic chamber; and a discharge circulating oil path for communicating the first hydraulic chamber with a drain port.

Abstract: In order to reduce hysteresis and other noise components included in the output signal characteristic of a differential pressure sensor, an elastic reaction member which operates together with a diaphragm provided in a chamber of the differential pressure sensor includes a contact portion which contacts the diaphragm, and a plurality of springs which are arranged symmetrically about the contact portion. Each of the springs is a plate shaped or linear shaped spring which is bent into the form of a letter C, U, J, or V, and has one of its ends fixed to a wall which defines the chamber, while its other end is connected to the contact portion. When the contact portion shifts together with the diaphragm, the deformations of the plurality of springs are mutually balanced, so that rotation and horizontal deviation of the contact portion with respect to the diaphragm is suppressed.

Abstract: A pressurized fluid feed system including a pressure compensating valve and directional control valve disposed between a hydraulic pump and a boom cylinder, and a pressure compensating valve and a directional control valve disposed between the hydraulic pump and a turning motor. Each pressure compensating valve comprise a check valve section and a pressure reduction valve section. The check valve section has an inlet port connected to the said hydraulic pump, an outlet port connected to the directional control valve, a spool for establishing and blocking communication between the inlet and outlet ports and a pressure chamber for applying pressure to the spool. The pressure reduction valve section has a first port connected to the said hydraulic pump, a second port connected to a reservoir, and a spool for establishing and blocking communication between the first and second ports.

Abstract: A directional control valve assembly having a pressure compensation valve in which there are provided a directional control valve in which a main spool is slidably inserted in a spool bore that is formed with a pump port, a first and a second load pressure detecting port, a first and a second actuator port, and a first and a second tank port; The pressure compensation valve that is connected with the pump port, includes: a pressure releasing zone which is adapted to the first and second load pressure detecting ports with the first and second tank ports when the spool lies its neutral position, and to block the first or second load pressure detecting port from the first or second tank port when the main spool lies at an intermediate site between the neutral position and a pressurized fluid supply position, and a passage having a counter flow preventing function for communicating the first or second actuator port and first and second load pressure detecting port with each other when the spool lies at an interme