Abstract: A servo regulator that causes a servo piston to move on the basis of working fluid pressure in two pressure chambers includes: a sleeve that is inserted into an insertion hole formed in a case and has a supply port capable of supplying a working fluid from a fluid pressure source to one of the pressure chambers; a spool valve disposed in the sleeve so as to be biased by a biasing member; and a solenoid that is attached to the case in order to drive the spool valve via a plunger. The sleeve includes a pressure receiving portion on which a fluid pressure of the working fluid from the fluid pressure source is exerted, and is pressed against an end surface of the solenoid by a biasing force acting on the pressure receiving portion.

Abstract: A pump volume control apparatus includes: a tilting piston; a pump volume switching valve configured to adjust a tilt driving pressure by a movement of a spool; a flow rate control spring configured to bias the spool in accordance with a tilt angle; a horsepower control piston configured to move in accordance with a pump discharge pressure; and a horsepower control spring configured to bias the horsepower control piston in accordance with the tilt angle. The tilt driving pressure is adjusted by means of the movement of the spool in accordance with a force acting on the spool in response to a flow rate controlling signal pressure in a flow rate controlled state, and is adjusted by means of the movement of the spool in accordance with a force acting on the horsepower control piston in response to the pump discharge pressure in a horsepower controlled state.

Abstract: A fluid pressure rotary machine includes a cylinder block that is fixed to a rotary shaft and includes a plurality of cylinder bores, a piston disposed to be free to slide in each cylinder bore such that a volume chamber is defined thereby, a swash plate that causes the piston to reciprocate such that the volume chamber expands and contracts, and a valve plate that slides against the cylinder block and includes an intake port and a discharge port communicating with the volume chamber. The valve plate includes a sliding surface formed to project in a spherical shape against the cylinder block. The cylinder block includes a sliding surface formed as an indentation corresponding to the shape of the sliding surface of the valve plate. A minute gap is formed between the sliding surface of the valve plate and the sliding surface of the cylinder block in an outer edge position.

Abstract: A swash plate type piston pump includes a plurality of pistons, a cylinder block including a plurality of cylinders for housing the pistons, a swash plate for reciprocating the pistons to expand and contract volume chambers of the cylinders with the rotation of the cylinder block, a biasing mechanism for biasing the swash plate in a direction to increase a tilting angle, a first control pin for driving the swash plate in a direction to reduce the tilting angle according to a first load pressure, and a second control pin for driving the swash plate in a direction to reduce the tilting angle according to a second load pressure. The first and second control pins are connected in series.

Abstract: A servo regulator that causes a servo piston to move on the basis of working fluid pressure in two pressure chambers includes: a sleeve that is inserted into an insertion hole formed in a case and has a supply port capable of supplying a working fluid from a fluid pressure source to one of the pressure chambers; a spool valve disposed in the sleeve so as to be biased by a biasing member; and a solenoid that is attached to the case in order to drive the spool valve via a plunger. The sleeve includes a pressure receiving portion on which a fluid pressure of the working fluid from the fluid pressure source is exerted, and is pressed against an end surface of the solenoid by a biasing force acting on the pressure receiving portion.