An axial reciprocation device having a main piston and an anchor piston coupled to one another via a swivel joint interconnecting 20 a pair of connecting rods, the main piston positioned in a main cylinder bore and the anchor piston positioned in an anchor piston bore of a housing, such that the main piston is configured for axial reciprocation in the main cylinder bore; wherein variable positioning of the anchor piston along the anchor piston bore results in variable displacement of the main piston of hydraulic fluid with respect to an inlet/outlet port of the housing.

A fluid-driven actuator system includes a fluid-driven actuator and at least one proportional control valve and at least one pump connected to the fluid-driven actuator to provide fluid to operate the fluid-driven actuator. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The fluid driven actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to adjust at least one of a flow in the fluid system to a flow set point and a pressure in the fluid system to pressure set point and a concurrently establishes an opening of the at least one proportional control valve to adjust at least one of the flow to the flow set point and the pressure to the pressure set point.

A low-energy and high pressure, hydraulic, pneumatic engine contains: a casing device, two main-cylinder devices, a holder device, two main-crankshaft devices, two recycle-valve devices, two swing-arm devices, two movable-valve devices, two recycle-cylinder devices, two recycle-crankshaft devices, and two umbrella-shaped gear devices. The engine operates without using gasoline or diesel, thus avoiding discharge of harmful substance or gas and pollution. The high pressure gas forces the hydraulic oil without using gasoline or diesel so as to start the engine, and the hydraulic oil recycles and reuses repeatedly, thus obtaining environmental protection. And the high pressure gas forces the hydraulic oil so as to circulate the hydraulic oil, and the communication of the low-energy and high pressure and the low pressure matches with the circulation space of the fluid operation to produce the torque, hence four strokes cycle of intake, compression, combustion and exhaust are not required.

A bent-axis hydrostatic axial piston machine (1) has a drive shaft (4) rotatable around an axis of rotation (R.sub.t) and having a drive flange (3). A cylinder drum (7) is rotatable around an axis of rotation (R.sub.z). The cylinder drum (7) includes a plurality of piston bores (8) concentric to the axis of rotation (R.sub.z) of the cylinder drum (7) and in each of which piston bores (8) there is a longitudinally displaceable piston (10). The pistons (10) are fastened in an articulated manner to the drive flange (3). Between the drive shaft (4) and the cylinder drum (7) there is a constant velocity driving joint (30) in the form of a cone-beam semi-roller joint (31).

A pressure medium powered device generating a reciprocating motion, which includes a body (5), a primary piston (2), a control valve assembly, and at least one secondary piston (3, 4). The primary piston (2) is fitted inside the body (5). The control valve assembly is configured to move the primary piston (2) back and forth. The secondary piston (3, 4) is attached to the primary piston (2). The primary piston (2) includes a first conical surface (20) and the secondary piston (3, 4) includes a corresponding second conical surface (21), whereby the primary piston (2) and the secondary piston (3, 4) are aligned to each other by means of the first conical surface (20) and the second conical surface (21).

An axial piston machine has a displacement volume that is adjustable by a double-acting control cylinder, which is connected to an auxiliary pump via a fluid flow path that includes a first, a second, and a third control assembly. The transfer point is the point of the fluid flow path at which the plate-like housing part contacts the pot-like housing part. The receiving bore of the first, second, and third control assemblies are each arranged directly in the pot-like housing part. The part of the fluid flow path which is arranged downstream of the transfer point extends over its entire length directly in the pot-like housing part.