Abstract: A bent-axis hydraulic pump motor includes: a cylinder block, a retainer plate; and a constant velocity joint, which includes an inner joint element; an outer joint element; and a plurality of balls interposed between block-side ball grooves and shaft-side ball grooves to transmit torque between the cylinder block and the retainer plate, so that all block-side groove planes, which include respective extending axial lines of the block-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a center shaft and all drive shaft-side groove planes, which include respective extending axial lines of the shaft-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a drive shaft such that loads applied to a cage in an axial direction from the balls are balanced.

Abstract: A bent-axis hydraulic pump motor includes: a cylinder block, a retainer plate; and a constant velocity joint, which includes an inner joint element; an outer joint element; and a plurality of balls interposed between block-side ball grooves and shaft-side ball grooves to transmit torque between the cylinder block and the retainer plate, so that all block-side groove planes, which include respective extending axial lines of the block-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a center shaft and all drive shaft-side groove planes, which include respective extending axial lines of the shaft-side ball grooves and the inclined rotation center, are inclined with respect to an axial center of a drive shaft such that loads applied to a cage in an axial direction from the balls are balanced.

Abstract: A center shaft of a bent axis type axial piston pump/motor includes an outer race, which is attached to a shaft attachment hole of a cylinder block, has a shaft portion accommodation hole at one end and has a spring accommodation hole at the other end, and an inner shaft, which includes a shaft supporting spherical head portion having a large outer shape dimension at a distal end of a shaft base portion and attached to the shaft portion accommodation hole of the outer race through the shaft base portion.

Abstract: A center shaft of a bent axis type axial piston pump/motor includes an outer race, which is attached to a shaft attachment hole of a cylinder block, has a shaft portion accommodation hole at one end and has a spring accommodation hole at the other end, and an inner shaft, which includes a shaft supporting spherical head portion having a large outer shape dimension at a distal end of a shaft base portion and attached to the shaft portion accommodation hole of the outer race through the shaft base portion.

Abstract: In a direct drive type hydraulic pump, the displacement of the hydraulic pump is forcedly changed to a desired displacement according to an instruction of a channel different from a usual instruction, thereby changing to a desired displacement quickly with good responsivity. When an emergency brake switch is turned on, an emergency brake signal is entered an emergency brake control valve. Thus, an emergency brake signal pressure is entered a piston through an emergency brake signal oil passage, and a piston is forcedly positioned in a neutral position. In other words, the piston can be forcedly positioned in the neutral position according to the emergency brake signal regardless of the entry of a usual brake signal. Therefore, the displacement of the hydraulic pump can be forcedly changed to the neutral position (minimum displacement).

Abstract: In a direct drive type hydraulic pump, the displacement of the hydraulic pump is forcedly changed to a desired displacement according to an instruction of a channel different from a usual instruction, thereby changing to a desired displacement quickly with good responsivity. When an emergency brake switch is turned on, an emergency brake signal is entered an emergency brake control valve. Thus, an emergency brake signal pressure is entered a piston through an emergency brake signal oil passage, and a piston is forcedly positioned in a neutral position. In other words, the piston can be forcedly positioned in the neutral position according to the emergency brake signal regardless of the entry of a usual brake signal. Therefore, the displacement of the hydraulic pump can be forcedly changed to the neutral position (minimum displacement).

Abstract: A travel drive apparatus for a hydraulic drive work vehicle of simple configuration, capable of preventing occurrence of cavitation which is predicted when a work vehicle is decelerated, descends a slope, or is changed from forward travel to reverse travel or from reverse travel to forward travel, and a control method thereof.

Abstract: A travel drive apparatus for a hydraulic drive work vehicle and control method therefor, the apparatus including: a travel hydraulic pump driven by the power of an engine; a hydraulic motor that receives discharged oil from the travel hydraulic pump and causes the vehicle to travel; a travel changeover valve that receives the discharged oil from the travel hydraulic pump, supplies the discharged oil to the hydraulic motor and discharges return oil from the hydraulic motor to a tank, in which the travel drive apparatus comprises; an accelerator for controlling an engine rotational speed; an operation unit for selecting vehicle forward travel, stop, and reverse travel; the travel changeover valve being adapted for receiving signals from the operation unit, switching the discharge oil supplied from the travel hydraulic pump to the hydraulic motor, and controlling vehicle forward travel, stop and reverse travel; a relief valve that regulates pressure for controlling the hydraulic motor when the vehicle has decele

Abstract: The present invention relates to a backpressure control circuit for a hydraulic drive device, which reduces the loss in drive power and which can suppress cavitation. Thus, the backpressure control circuit for hydraulic drive devices is a hydraulic drive circuit: for supplying to a hydraulic motor pressurized oil discharged from a hydraulic pump through a direction changeover valve, which is switched upon receipt of a pilot pressure; and for permitting at the time of braking by the hydraulic motor, a throttle valve to throttle return oil from the hydraulic motor and oil discharged from the hydraulic pump to generate a backpressure to supply pressurized oil to the hydraulic motor via a check valve for prevention of cavitation.

Abstract: In a counter balance valve, a valve body is provided with a valve bore having first and second pump-side ports, first and second motor-side ports and an auxiliary port. A spool is slidably fitted in the valve bore in a longitudinal direction thereof to establish and block communication between the respective ports. Left and right springs maintain the spool at a neutral position in which the respective ports are closed. A left pressure receiving chamber shifts the spool by a pressure oil supplied therein to a first travelling position at which the first pump-side port and the auxiliary port are communicated with each other and the second pump-side port and the second motor-side port are also communicated with each other.

Abstract: A damper for a hydraulic pilot valve having a valve body in which a plurality of pressure reducing valves, a rotational shaft, an operation member attached to the rotational shaft and a handling member rotating the rotational shaft are provided. The pressure reducing valves are operated through the operation member by rotating the rotational shaft by the handling member, and the damper is disposed in the valve body and is adapted to apply an operational resistance to the operation member due to a viscous resistance of a fluid having high viscosity.

Abstract: The present invention relates to a hydraulic circuit for a hydraulically driven working vehicle which allows the vehicle to travel at an almost constant speed during high-speed traveling, provides a great digging force during working, does not need a charging pressure for preventing cavitation, loses a small amount of energy, and has a simple structure. To this end, the hydraulic circuit has a hydraulic travel pump (2) and a working machine hydraulic pump (4) which are driven by the power of an engine (1) for discharging pressurized oil to a HST travel circuit and a working machine-driving hydraulic circuit, respectively, wherein pressurized oil from the working machine hydraulic pump (4) joins pressurized oil from the hydraulic travel pump (2) to effect high-speed traveling, while pressurized oil from the hydraulic travel pump (2) joins pressurized oil in the working machine hydraulic pump (4) to generate a large digging force to effect digging.

Abstract: A hydraulic motor driving apparatus includes a directional control valve for supplying discharge pressure fluid from a hydraulic pump into a first or second port of a hydraulic motor and returning the hydraulic fluid from the second or first port into a tank, and a pilot pressure applying valve for controlling the directional control valve. The directional control valve is urged to its neutral position by springs, to its first position by hydraulic pressure against its first pressure receiving portion and to its second position by hydraulic pressure against its second pressure receiving portion. Discharge pressure fluid from the hydraulic pump is supplied via a check valve into the first and second ports of the hydraulic motor when the directional control valve is at the neutral position. The discharge pressure fluid is supplied into the first port of the hydraulic motor and a hydraulic pressure fluid of the second port flows into the tank, when the directional control valve is at the first position.

Abstract: There is disclosed an apparatus for controlling the capacity of a hydraulic motor (5) in a hydraulically driven motor vehicle, which comprises: a hydraulic pump (2) adapted to be driven by an engine (1) having a variable rotation speed; the hydraulic motor of a variable capacity type adapted to be rotated by a discharge pressure fluid from the hydraulic motor for driving a traveling body that constitutes the motor vehicle allowed to travel; a capacity control section for reducing the capacity of the hydraulic motor when the rotation speed of the engine is increased and for increasing the capacity of the hydraulic motor when the rotation speed of the engine is reduced, the capacity control section having a variable operation rate and being operable at a variety of positions among a maximum capacity position, an intermediate capacity position and a minimum capacity position; and an operation rate control unit for accelerating the operation rate of the capacity control section when it is operating at a position

Abstract: There is provided a hydraulic braking apparatus, characterized in that it comprises: a first safety valve for draining a high pressure fluid at the side of a second port of a hydraulic motor into the side of a first port thereof; a second safety valve for draining a high pressure fluid at the side of the said first port of the said hydraulic motor into the side of the said second port thereof; and a braking valve adapted to be switched from a neutral position to a first position or a second position under a difference in pressure between the said first port and the said second port, the inlet side of each of the said first safety valve and the said second safety valve having a communication via the said braking valve with the side of each of the said first port and the said second port, and having an increased area of such communication when the said braking valve is set in the said neutral position and a reduced area of such communication when the braking valve is switched to the said first position or to th

Abstract: A damper for a hydraulic pilot valve having a valve body in which a plurality of pressure reducing valves, a rotational shaft, an operation member attached to the rotational shaft and a handling member rotating the rotational shaft are provided. The pressure reducing valves are operated through the operation member, by rotating the rotational shaft by the handling member, and the damper is disposed in the valve body and is adapted to apply an operational resistance to the operation member due to a viscous resistance of a fluid having high viscosity.

Abstract: In a piston pump/motor of swash plate type which comprises: a cylinder block disposed in a casing to be rotatable jointly with a shaft therein; a plurality of pistons slidably inserted in the cylinder block parallel to the shaft; and a swash plate swingably attached to the casing for guiding the plurality of pistons on a front surface thereof and changing a displacement of each of the pistons by changing an inclination thereof, there is provided a swash plate angle changing apparatus in which the swash plate has a rear surface formed with a first contact surface and a second contact surface which make an angle between them. The casing has a swash plate support surface which is perpendicular to the shaft and with which the first contact surface and the second contact surface are each adapted to contact.

Abstract: An electrical lever assembly includes a lever rockably supported on a main body, a rod vertically sliding with a disc provided on the lever, a potentiometer having a horizontally rotating shaft mounted on the lower surface of the main body, and an arm connecting the potentiometer and the rod. The potentiometer is mounted on the lower surface of the main body in a condition adjustable with respect to a position in a vertical direction and a horizontal direction.

Abstract: There is provided a coupling joint for coupling a shaft (23) to a rotary axis (25a) of a rotary angle sensor (25) mounted on a valve body. The coupling joint includes an engagement recess portion (40) formed on the shaft, a coupling member (41) engageable with the engagement recess portion, and a projection (42) formed on the rotary shaft for engagement with an angular hole (45) of the coupling member. Also, the coupling member is constructed by a pair of first opposing sides (43) and a pair of second, wave-form or zig-zag opposing sides (44) forming a configuration having an angular opening. The pair of first sides are formed to fit into the engagement recess portion of the shaft. The projection fits between the pair of second sides.

Abstract: A hydraulic pilot valve consisting of a pair of pressure-reducing valves, wherein a stopper which can freely adjust maximum control inputs of operating levers (23, 24) of the hydraulic pilot valve is provided to make maximum pilot pressures output from the pair of pressure-reducing valves freely adjustable. Furthermore, in the hydraulic pilot valve, a stopper member for limiting a maximum control input of an operating lever is fixed to the operating levers (23, 24), so that an operating force during a maximum operation of an operating lever is received by the stopper member. Furthermore, in the hydraulic pilot valve, an erroneous operation due to vibrations and the like is prevented by a damper mechanism (50) interposed between a lever fixed to each of the operating levers (23, 24) and a main body (1) of the valve.