A gap seal device includes a housing with a fluid-filled guiding chamber and a multi-part piston that is translationally and/or rotationally moveable in the guiding chamber. The piston separates a high-pressure region from a low-pressure region of the guiding chamber. The piston forms an annular gap having a nominal gap width with an inner wall delimiting the guiding chamber. The piston has a stepped rod, a sleeve, which is slipped over a stepped-down region of the rod and which has a blind hole, and a coupling. The stepped-down region of the rod or in a tube portion of the sleeve includes a stiffness change. A gap width of the annular gap that is reduced compared with the nominal gap width can be set in a region radial to the stiffness change by stress-caused expansion of an outside diameter of the tube portion of the sleeve in accordance with the set stressing force.

A piston for a fluid-actuated working cylinder, with a piston base unit which is coaxial to a piston longitudinal axis, consisting of a rigid core body which has radial outer peripheral surface and of an annular filling body which is seated in an annular receiving groove. The receiving groove is coaxial to the piston longitudinal axis and in the region of the radial outer peripheral surface is designed with a radially outwardly facing groove opening in the core body. The piston further includes a ring element which consists of plastic. The ring element radially outwardly coaxially encompasses the piston base unit at least in the region of the filling body, being radially supported with a radial inner peripheral surface on the piston base unit, projecting radially beyond the radial outer peripheral surface of the core body and comprising an axially orientated axial support surface radially outside the piston base unit on its two axial face sides. The piston further includes an annular enveloping body which has rubber elastic characteristics.

A piston for a compressor includes a bearing portion having a cylindrical shape to define a suction space into which refrigerant is accommodated therein, the bearing portion being provided with a bearing surface facing an inner circumferential surface of the cylinder, a head portion coupled to a front opening of the bearing portion and provided with a plurality of suction ports which communicate with the suction space, the head portion having a compression surface configured to face a compression space to compress the refrigerant in the compression space, and a flange portion coupled to a rear opening of the bearing portion and provided with a through-passage through which the refrigerant is introduced from a muffler unit to the suction space, the flange portion being coupled to a driving portion to transmit driving force to the piston. The bearing surface is subjected to a surface treatment to improve abrasion resistance.

An internal combustion may include a cylinder having a first combustion chamber at one end and a second combustion chamber at an opposing end, first and second cylinder heads located at an end of the first and second combustion chambers, respectively, and a double-faced piston slidably mounted therein. The piston may be configured to move in a first stroke that includes an expansion stroke portion and a non-expansion stroke portion. The engine may further include first and second piston rod portions extending from opposite faces of the piston. A recess in the piston rod portions may be configured to communicate gases between a combustion chamber and locations outside the cylinder. There may also be a chamber surrounding the first or second piston rod portion, the chamber configured to be supplied with gas and the chamber being isolated from the first combustion chamber and the second combustion chamber.

Provided is a plunger including: a plunger body; a first surface configured to come into contact with an inner peripheral surface of the cylindrical member; a second surface disposed on a base end side relative to the first surface, the second surface having an outer diameter that is smaller than that of the first surface; an outer stepped surface disposed between the first surface and the second surface; a first housing disposed in an area at least partly corresponding to the second surface in the recess, the first housing being provided for housing a tip part of the pin; a second housing disposed on the base end side relative to the first housing, the second housing having an inner diameter that is smaller than a largest inner diameter of the first housing; and an inner stepped surface disposed between the first housing and the second housing.

A wear-preventive air-charger piston structure is provided. The piston rod has a top forming a piston top seat on which a piston ring is disposed. The piston ring is covered with a top cover that is combined with the piston top seat. The top cover is provided with an airtight plate mounted thereto to form a complete piston structure. A buffering element is arranged between the piston top seat and the piston ring. The buffering element has an outside diameter smaller than the piston ring, so that when the piston ring, which is driven by a crankshaft to do an up-and-down movement, is put in an inclined oscillating condition and at a high position of an oscillation side, the buffering element functions to absorb the stress acting on the piston ring at the high position of the oscillation side to effectively prevent detachment and breaking of the piston ring.

A wear-preventive air-charger piston structure is provided. The piston rod has a top forming a piston top seat on which a piston ring is disposed. The piston ring is covered with a top cover that is combined with the piston top seat. The top cover is provided with an airtight plate mounted thereto to form a complete piston structure. A buffering element is arranged between the piston top seat and the piston ring. The buffering element has an outside diameter smaller than the piston ring, so that when the piston ring, which is driven by a crankshaft to do an up-and-down movement, is put in an inclined oscillating condition and at a high position of an oscillation side, the buffering element functions to absorb the stress acting on the piston ring at the high position of the oscillation side to effectively prevent detachment and breaking of the piston ring.

There is provided a compressor including: a piston that reciprocates inside a cylinder; a valve plate that closes an end portion of the cylinder; a connecting rod that supports the piston; a crankshaft that applies a rotating force to an end portion of the connecting rod; and a crankcase that rotatably supports the crankshaft. The piston is an oscillating piston that reciprocates while oscillating inside the cylinder according to rotation of the crankshaft. A central axis of an inner diameter of the cylinder is disposed at a position shifted by an offset amount e with respect to a rotation center axis of the crankshaft. An upper surface of the piston is substantially parallel to a crankcase side surface of the valve plate in a state where the piston is at a top dead center.

A clutch assembly for a transmission of an agricultural work vehicle. The clutch assembly includes a housing, a clutch pack located within the housing, a piston chamber located within the housing, and a multipart piston located within and slidable relative to the piston chamber. The multipart piston is operably connected to the clutch pack for engaging and disengaging the clutch pack. The multipart piston includes a lower piston extension part. The clutch assembly further includes a balance chamber that is located within the housing. The lower boundary wall of the balance chamber and the lower boundary wall of the piston chamber are radially separated from one another by a substantial distance. The lower piston extension part is located within the balance chamber for adding to a collective surface area of the balance chamber.

A reciprocating rod pump apparatus includes a pump barrel having an inner bore; a plunger comprising a plurality of plunger segments, disposed within the pump barrel; and an articulating connector disposed between and connecting plunger segments, adapted to allow for deflection between plunger segments.