A weight training apparatus using hydraulics or pneumatics for applying positive and negative resistance closer to a user's maximum capacity throughout a lift is provided. The apparatus allows for weight training without weights. The apparatus may provide a more effective and safer mechanism for training than conventional techniques. An aerobic apparatus using hydraulics or pneumatics for a more realistic feel is also provided. Methods of using the devices are also provided.

The linear actuator comprises a double-chamber solenoid pump comprising at least one pump coil, a multi-way valve and at least one pump armature that can be moved by energizing the at least one pump coil and is provided with a switching armature by means of which the multi-way valve can be switched and which can be moved by energizing the at least one pump coil. In the method, both the switching armature and the pump armature are moved by energizing the pump coil.

A thrust bearing assembly is provided for the pistons of a hydrostatic drive motor. The thrust bearing assembly includes first and second retainer components removably interconnected to form a retainer assembly, a thrust bearing captured between and encompassed by the first and second retainer components, and locking tangs extending outward from the first and second retainer components. Corresponding catches are formed on the internal surface of the housing to engage the locking tangs when the thrust bearing assembly is installed in the housing.

A continuously variable displacement engine has a plurality of pistons received in a cylinder block and connected to a nutator. A crankshaft with an axis of rotation is carried in a crankcase and incorporates an upper journal with a first angle relative to the axis and a lower journal with a second angle with respect to the axis. A first slider ball is engaged on the upper journal and a second slider ball engaged on the lower journal. A carrier assembly captures the first and second slider balls and incorporates an actuating cylinder. An actuation piston assembly is translatably carried in the actuating cylinder and connected to the crankshaft intermediate the upper journal and lower journal. The actuating piston is controllably translated between a first high eccentricity position and second low eccentricity position. An anti-rotational assembly connects the nutator to a piston case. A balance mechanism is adapted to change the amount of counterbalance for the nutator and the axial location of the counterbalance consistent with eccentricity of the nutator.

An axial piston machine may include a rotor with a shaft. A plurality of cylinders may be arranged in an annular manner about the shaft. A plurality of pistons may each be positioned within each of the plurality of cylinders and may be constructed and arranged to move translationally within the plurality of cylinders. A cylinder head may include a plurality of inlet openings and may be in operative communication with the plurality of cylinders. A sealing washer having a plurality of passage openings may be disposed on the cylinder head so that the plurality of passage openings and the plurality of inlet openings may be flush with one another. A number of the plurality of inlet openings may correspond to a number of the plurality of passage openings. A valve plate may be connected to the shaft in a rotationally fixed manner and may be constructed and arranged to be brought into congruence with the plurality of passage openings of the sealing washer based on a rotary angle. The sealing washer may be disposed between the plurality of inlet openings and the valve plate and may be prestressed against the cylinder head and onto the inlet openings.

A variable stroke high pressure pump is disclosed. The pump uses a wobble plate design with dynamically variable tilt to provide continuous adjustment of pump stroke length and output. Dynamically variable tilt is accomplished using a linearly actuated tilt thruster rotationally coupled to the drive shaft to maintain a selected tilt of the wobble plate through the rotation of the wobble plate.

Hydraulic axial piston unit (1) of the swashplate construction type having a drive shaft (2) adapted to drive or be driven by a cylinder block (4). The cylinder block comprises a plurality of cylinder bores (6), in which several pistons (8) are moveable in general along the rotational axis (10) of the drive shaft (2) and relative to the cylinder bores (6). First ends of the pistons (8) protrude outside of the cylinder bores (6) and are slidable fixed by means of slippers (14) to a swashplate (16). The slippers (14) are hold down in a sliding manner on a sliding surface (18) of the swashplate (16) by means of a slipper hold down ring (20) arranged parallel to the sliding surface (18). The slipper hold down ring (20) is in a sliding contact with its radial inner surface (22) with a matching surface (26) on a guide ball (24) rotationally fixed on the drive shaft (2) and axially moveable in direction of the rotational axis (10) relative to the cylinder block (4) against resilient forces of springs (28) characterized in that a mounting ring (30) is attached to the cylinder block (4) in order to limit the axial movement of the guide ball (24) towards the cylinder block (4).

An opposed piston engine has a driveshaft with at least one combustion cylinder positioned between opposing, curvilinear shaped cams mounted on the driveshaft, where the center axis of the combustion cylinder is parallel with but spaced apart from the driveshaft axis. A piston assembly is disposed in each end of the cylinder, with one piston assembly engaging one cam and the other piston assembly engaging the other cam. Each piston assembly includes a cam follower that can move along a curvilinear shaped cam to reciprocate the piston assembly within the cylinder. The combustion cylinder includes an intake port in fluid communication with an annular intake channel formed in the engine block in which the cylinder is mounted, and an exhaust port in fluid communication with an annular exhaust channel formed in the engine block.

An axial piston machine may include a rotor having a shaft rotatably mounted in a housing. A plurality of cylinders may be arranged annularly around the rotor. A plurality of pistons may each be disposed within each of the plurality of cylinders and may be constructed and arranged to selectively translate within each of the plurality of cylinders. Each of the plurality of cylinders may be disposed within a cylinder head and may be in operative communication with an inlet opening defined in the cylinder head and at least one outlet opening defined in the housing. An auxiliary outlet rotary slide valve may be operatively connected to the shaft in a rotationally fixed manner. The auxiliary outlet rotary slide valve may comprises an auxiliary outlet rotary opening constructed and arranged to connect to a vent duct of one of the plurality of cylinders based on an angle of rotation, and may vent the one of the plurality of cylinders. At least a portion of the auxiliary outlet rotary slide valve may comprise a material constructed and arranged to reduce a sliding friction resistance, and wherein the material comprises one of a carbon containing material or a polymer containing material.

A swash plate compressor in which a lubricating film is not formed on a sliding contact surface of the swash plate and the piston owing to the use of the semispherical shoe. The semispherical shoe (4) is subjected to sliding contact with the swash plate of the swash plate compressor and the piston thereof. A base material (5) consists of a metallic member having a resin layer (6b) formed on a surface of a planar part (4b) that is subjected to sliding contact with the swash plate. A resin layer (6a) is formed on a surface of a spherical part (4a) to be subjected to sliding contact with the piston. The resin layer (6a) and the resin layer (6b) are integral with each other. At least one portion of the base material (5) is exposed.