The invention relates to a hydraulic actuator comprising a cylinder (1) in which a piston (2) secured to a rod (4) is mounted so as to slide in a sealed manner in order to delimit in the cylinder a hydraulic extension chamber (5) and a hydraulic retraction chamber (6) that are connected to respective ports, the hydraulic actuator comprising means for slowing the piston when the piston approaches a retracted position. According to the invention, the slowing means comprise first and second hydraulic lines (7, 8) extending between the extension port and the extension chamber, the first hydraulic line comprising a seat (13) while the piston bears a retractable finger (10) having an end (14) that comes to bear against the seat in order to close the first hydraulic line (7) when the piston approaches the retracted position, such that only the second hydraulic line (8) remains open while the piston completes its travel towards the retracted position.

Landing gear and aircraft comprising such an actuator.

A hydraulic cylinder is provided with a cylinder tube, a piston unit, and a piston rod. The piston unit has a piston body; packing mounted on the piston body; a holding member mounted on the piston body; and a magnet held by a magnet holding part of the holding member. The magnet holding part has a notch that is open on the outer circumferential surface of the holding member.

A control unit for pneumatic actuation of a cylinder, in particular an active creel of a textile-processing machine or a cabling machine, having a compressed air inlet for connecting a compressed air supply, a working air outlet for operating the cylinder, which acts at least on one side, a valve unit arranged between the compressed air inlet and the working air outlet, and an operating element for opening the valve unit to trigger a lifting movement of the cylinder. In order to provide a control unit for pneumatic actuation of an active creel, the actuation of the creel being particularly simple by the control unit, so that an operator can use the creel more easily, quickly and safely, and in addition the creel is protected from damage by incorrect operation, the control unit for achieving a self-retaining valve function, in which the lifting movement of the cylinder is fully executed with a single and/or brief actuation of the operating element, and for the control unit is connected to an end position sensor of the cylinder such that, when the end position sensor is activated, the valve unit is closed and/or the cylinder connected to the working air outlet is automatically depressurised when or after an end position is reached.

A hydraulic buffer pertains to the field of hydraulic parts. A signal device (X) is installed at a position close to an end of a cylinder stroke to control movement of slide valves (12, 18, 12a, 12b, 12c, 12d, 12e, 12f, F1, F2, F3, F4) of the hydraulic buffer, to dynamically adjust the degree of valve openness and a liquid flow direction of a buffering module (Y), and therefore control pressure of oil entering an oil returning chamber of a cylinder. The high-pressure chamber of the cylinder releases pressure and unloads, and/or the oil returning chamber throttles to load pressure, such that a moving speed of a cylinder piston (6) at the end of the stroke is controlled, realizing buffering of the cylinder. The device eliminates defects in the prior art in which a buffering mechanism of a cylinder is complex, manufacturing accuracy requirements are high, structural arrangement is difficult, it is difficult to employ a combined configuration in which an oil returning chamber throttles to load pressure and a high-pressure chamber releases pressure and unloads, and buffering efficiency is not high. The device has desirable buffering controllability and high reliability, such that the overall quality is improved.

A piston unit is provided with a piston body; a packing mounted on an outer circumferential portion of the piston body; a holding member having a plurality of magnet holding portions that are arranged along a circumferential direction; a plurality of magnets which are held at intervals in the circumferential direction; a first annular yoke disposed on one side in an axial direction of the plurality of magnets; and a second annular yoke disposed on the other side in the axial direction of the plurality of magnets.

A steam reciprocating piston engine that uses a pressurized working fluid to drive first and second pistons in reciprocating power strokes is disclosed. A piston is configured for reciprocating motion within the cylinder and traverses between bottom dead center and top dead center positions. An uppermost stop is reached wherein the working fluid is allowed to escape the cylinder through one or more exhaust ports whereby the fluid travels through a closed loop circuit ultimately directing pressurized fluid back into the cylinder inlet. Momentum causes a spring connected mass to continue upward maintaining the piston above the exhaust port so as to allow escape of the working fluid. Return of the piston and mass is caused by opposite movement of a second piston whereby another stroke is initiated. Power output may be transferred to any suitable system.

A pair of air cylinders that cause a valve plate to perform an opening/closing operation each include a head-side air cushion mechanism and a rod-side air cushion mechanism. Each head-side air cushion mechanism includes a head-side communication path and a head-side restricting flow path that connect a head-side pressure chamber and a head-side main flow path in parallel, and a blocking mechanism that blocks the head-side communication path when a piston approaches a retreat stroke end, and each rod-side air cushion mechanism includes a rod-side communication path and a rod-side restricting flow path that connect a rod-side pressure chamber and a rod-side main flow path in parallel, and a blocking mechanism that blocks the rod-side communication path when the piston approaches an advance stroke end.

A piston's stroke length may be restricted by passing a rod through a through hole in the piston. The stroke length's boundaries may be defined by the points where an interior of the through hole contacts an exterior of the rod. Adjusting a position or orientation of the rod may alter this stroke length. If the rod comprises a noncylindrical external geometry, a radius thereof may vary along an axial length of the rod or around a circumference thereof. Adjustment of the rod, via axial translation or rotation for example, may change the position of contact between the rod and the through hole. Alternately, the through hole may comprise a unique geometry in which the rod may radially translate to adjust the piston's stroke length.

In an interior of a cylinder tube of a fluid pressure cylinder, a piston unit is provided, which is displaced along an axial direction under the supply of a pressure fluid. The piston unit includes a disk shaped plate body, which is connected to one end of a piston rod, and a ring body connected to an outer edge portion of the plate body. The plate body is connected to the piston rod by plural second rivets, which are punched in an axial direction with respect to the piston rod.

In a sealed compressor (100) of the present invention, a valve plate (150) is provided with a plurality of discharge holes (151a, 151b) and a plurality of discharge valves (171a, 171b) which open and close the plurality of discharge holes. A tip end surface (160a) of a piston (160) is provided with a plurality of convex portions (161a, 161b), at least tip end portions of which are located inside of the discharge holes (151a, 151b) in a state in which the piston (160) is located at a top dead center. When a plurality of discharge passages (172a, 172b) of the refrigerant gas are defined as spaces formed between convex portion side surfaces (162a, 161b) and discharge hole inner peripheral surfaces (152a, 152b), in a state in which the plurality of convex portions (161a, 161b) are located inside of the plurality of discharge holes (151a, 151b), respectively, the volumes of the plurality of convex portions (161a, 161b) are made different from each other, to make the total cross-sectional areas of the plurality of discharge passages (172a, 172b) different from each other.