Abstract: A piston pump includes: a first biasing mechanism configured to bias a swash plate in accordance with control pressure supplied; a second biasing mechanism configured to bias the swash plate against the first biasing mechanism; and a regulator configured to control the control pressure in accordance with self-pressure of the piston pump. The regulator has: an outer spring and an inner spring configured to be extended and compressed by following tilting of the swash plate; a control spool configured to be moved in accordance with biasing forces exerted by the outer spring and the inner spring, the control spool being configured to adjust the control pressure; an auxiliary spring configured to exert biasing force to the control spool against the biasing forces exerted by the outer spring and the inner spring; and an adjusting mechanism configured to adjust the biasing force exerted by the auxiliary spring.

Abstract: A pump displacement control device includes: a servo piston that changes a tilt angle; a flow rate control spool that is displaced corresponding to an input pressure; a power control spool that is displaced corresponding to a discharge pressure of the pump; a control pressure regulating spool that regulates a control pressure which controls the servo piston; and a feedback lever connected to the servo piston and the control pressure regulating spool. The feedback lever directly abut on either one of the flow rate control spool or the power control spool for regulating the control pressure.

Abstract: A piston pump includes: a tilting mechanism configured to bias a swash plate in accordance with a control pressure; a support spring configured to support the swash plate; and a regulator configured to control a control pressure guided to the tilting mechanism in accordance with a self-pressure of the piston pump. The regulator has an outer spring and an inner spring configured to be extended and compressed by following tilting of the swash plate; and a control spool configured to be moved in accordance with a biasing force from the outer spring and the inner spring, the control spool being configured to regulate the control pressure, and the outer spring and the inner spring and the support spring are provided adjacent to each other and in parallel with respect to the swash plate.

Abstract: A piston pump includes: a tilting mechanism configured to bias a swash plate in accordance with a control pressure; a support spring configured to support the swash plate; and a regulator configured to control a control pressure guided to the tilting mechanism in accordance with a self-pressure of the piston pump. The regulator has an outer spring and an inner spring configured to be extended and compressed by following tilting of the swash plate; and a control spool configured to be moved in accordance with a biasing force from the outer spring and the inner spring, the control spool being configured to regulate the control pressure, and the outer spring and the inner spring and the support spring are provided adjacent to each other and in parallel with respect to the swash plate.

Abstract: A piston pump includes: a first biasing mechanism configured to bias a swash plate in accordance with control pressure supplied; a second biasing mechanism configured to bias the swash plate against the first biasing mechanism; and a regulator configured to control the control pressure in accordance with self-pressure of the piston pump. The regulator has: an outer spring and an inner spring configured to be extended and compressed by following tilting of the swash plate; a control spool configured to be moved in accordance with biasing forces exerted by the outer spring and the inner spring, the control spool being configured to adjust the control pressure; an auxiliary spring configured to exert biasing force to the control spool against the biasing forces exerted by the outer spring and the inner spring; and an adjusting mechanism configured to adjust the biasing force exerted by the auxiliary spring.

Abstract: A pump displacement control device includes: a servo piston that changes a tilt angle; a flow rate control spool that is displaced corresponding to an input pressure; a power control spool that is displaced corresponding to a discharge pressure of the pump; a control pressure regulating spool that regulates a control pressure which controls the servo piston; and a feedback lever connected to the servo piston and the control pressure regulating spool. The feedback lever directly abut on either one of the flow rate control spool or the power control spool for regulating the control pressure.

Abstract: In an anti-reverse valve, a first communication passage that allows the first supply and discharge passage to communicate with the first pressure chamber and a second communication passage that allows the second supply and discharge passage to communicate with the second pressure chamber are provided inside the spool, a first restrictor is provided in the first communication passage, a second restrictor is provided in the second communication passage, and a first annular groove that allows the first supply and discharge passage to communicate with the drain passage when the spool is placed at the first communication position and a second annular groove that allows the second supply and discharge passage to communicate with the drain passage when the spool is placed at the second communication position are provided in an outer periphery of the spool.

Abstract: A brake device that puts a brake on a hydraulic motor includes a disc plate configured to rotate with a cylinder block, a brake piston supported by a first case, and brake springs compressed and placed between the brake piston and a second case. The second case has a dent shaped or projection shaped holding portion into which one ends of the brake springs are inserted, and the brake springs are held by the holding portion even in a state where the other ends are away from the brake piston.

Abstract: In a swash plate piston motor (2), a piston (24, 41) which is caused to reciprocate by a fluid pressure and a cylinder block (23) which rotates within an operating chamber (21) in accordance with the reciprocation of the piston (24, 41) are accommodated in the operating chamber (21) inside a case (30). When the cylinder block (23) rotates through inertia after a supply of working fluid to a working fluid passage (11, 12) for applying the fluid pressure to the piston (24, 41) has been shut off, a check valve (18) supplies working fluid in the operating chamber (21) to the working fluid passage (11, 12) through a communicating passage (14) if necessary. As a result, the interior pressure of the fluid pressure motor (2) is prevented from becoming negative, and the piston (24, 41) is prevented from floating up from a swash plate (25).

Abstract: A relief valve includes a high-pressure port (14) communicating to a hydraulic circuit (41), a low-pressure port (15) communicating to a drain circuit (42), a valve (11) supported so as to be movable in back and forward in the axial direction thereof to open and close between these ports (14, 15), a piston (12) supported so as to be movable in the coaxial direction in relation to the valve (11), a spring (13) interveningly provided between the valve (11) and the piston (12) for biasing the valve (11) to a valve closing direction against the pressure of the high-pressure port (14), a damping chamber (20) defined at back side of the piston (12), pressure guiding paths (26, 27) for guiding the pressure in the upstream side of the valve (11) to the damping chamber (20), and a plurality of orifices (30a to 30d) exchangeably arranged in series in the pressure guiding paths (26, 27).