An actuator of a compressor includes a partitioning body, which is rotatable integrally with a drive shaft and loosely fitted to the drive shaft in the swash plate chamber, a movable body, which is coupled to a swash plate and movable relative to the partitioning body along the axis of the drive shaft, and a control pressure chamber, the pressure of which moves the movable body. A control mechanism changes the pressure of the control pressure chamber to move the movable body. A link mechanism shifts a top dead center of a first head of a piston over a longer distance than a top dead center of a second head of the piston when the inclination angle of the swash plate changes. The actuator is located at the same side as the first cylinder bore, which accommodates the first head, as viewed from the swash plate.

A mounting member for a hydraulic pump or other rotating kit for a hydraulic drive device includes a running surface having a pair of arcuate kidney ports formed thereon. The running surface also includes a plurality of pressure gradient grooves formed on the running surface, each pressure gradient groove having a proximal end adjacent to a respective one of the ends of one of the kidney ports and a distal end. The distal end of one of the pressure gradient grooves associated with one kidney port may overlap the distal end of a pressure gradient groove associated with the other kidney port. The distal end of at least one of the pressure gradient grooves is located outside the circumference of a pitch circle that passes through the center of each of the kidney ports. The distal end of at least one of the other pressure gradient grooves is located inside the circumference of the pitch circle.

A variable displacement swash plate type compressor includes a rotary shaft, a swash plate, and an actuator capable of changing the inclination angle of the swash plate. The actuator includes a movable body. The movable body includes a sliding portion that slides on the rotary shaft or the lug member and a movable body-side transmission portion that engages with the swash plate at a position radially outward of the rotational axis of the swash plate. The movable body-side transmission portion is configured such that a perpendicular line or a normal to the movable body-side transmission portion and the rotational axis of the rotary shaft intersect with each other in a zone surrounded by the sliding portion when viewed in a direction that is perpendicular to a direction in which the rotational axis of the rotary shaft extends and perpendicular to the first direction.

A swash plate type liquid-pressure rotating device includes a movement restricting mechanism configured to restrict a movement of a spherical bushing relative to a rotating shaft toward a first side in an axial direction. The movement restricting mechanism is a restricting member such that a portion of the spherical bushing which portion is located at the first side in the axial direction contacts the restricting member. The swash plate type liquid-pressure rotating device further includes: a stopper attached to the rotating shaft; and a gap adjusting member. The gap adjusting member is inserted into a gap G3 formed between the stopper and the bearing when the spherical bushing, the retainer plate, the shoe, and the swash plate tightly contact one another in the axial direction. The gap adjusting member restricts a movement of the rotating shaft relative to the casing toward the first side in the axial direction.

The rod-free mechanisms are used for converting rotational motion into reciprocating motion and vice versa. The mechanism can be used in displacement pumps and compressors, as well as in internal and external combustion engines, cubic expansion engines, steam engines, hydro and pneumatic engines. Coulisse-eccentric motor automatically feeds and distributes the actuation fluid to the swept-volume capacities. Coulisse-eccentric motor is easy to manufacture, contains a minimum of parts, such as a housing, a coulisse and an eccentric, can be made entirely of ceramics, and allows converting the pressure difference between the two internal volumes of the coulisse into rotational motion on the shaft, and vice versa. Coulisse-eccentric motor in motion allows reversing, changing the shaft torque and compression ratio, while all engine components operate normally and are not subjected to excessive loads.