A piston arrangement comprising: a piston, a first chamber, a second chamber and a power transfer assembly; wherein the piston comprises a first head movable within the first chamber and a second head movable within the second chamber; wherein, in operation, the piston follows a linear path in reciprocating motion along a first axis; wherein the power transfer assembly comprises a shaft rotatably coupled to a shuttle bearing and arranged to convert the reciprocating motion of the piston to rotary motion of the shaft; wherein the shuttle bearing moves relative to the piston in reciprocating motion along a second axis substantially transverse to the first axis; and wherein the shuttle bearing is coupled to the piston via a non-planar bearing surface thereby allowing rotation of the shuttle bearing.

A piston arrangement comprising: a piston, a first chamber, a second chamber and a power transfer assembly; wherein the piston comprises a first head movable within the first chamber and a second head movable within the second chamber; wherein, in operation, the piston follows a linear path in reciprocating motion along a first axis; wherein the power transfer assembly comprises a shaft rotatably coupled to a shuttle bearing and arranged to convert the reciprocating motion of the piston to rotary motion of the shaft; wherein the shuttle bearing moves relative to the piston in reciprocating motion along a second axis substantially transverse to the first axis; and wherein the shuttle bearing is coupled to the piston via a non-planar bearing surface thereby allowing rotation of the shuttle bearing.

A magnet-type rodless cylinder (1) is provided with a guide mechanism having an outer rolling groove (26), an inner rolling groove (29), a cylinder body (32), a pair of connection paths (34) for connecting an area between the outer rolling groove and the inner rolling groove with the cylinder body, and a plurality of steel balls (36) that can roll within an endless circuit (35) formed of the cylinder body, the connection paths and the area between the outer rolling groove and the inner rolling groove, wherein the connection paths (34) are formed at a pair of inner members, i.e. return caps (33), disposed on the inner sides of metal end plates (12) that are attached to the front and rear ends in the sliding direction of a sliding body (4).

A magnet-type rodless cylinder (1) is provided with a guide mechanism having an outer rolling groove (26), an inner rolling groove (29), a cylinder body (32), a pair of connection paths (34) for connecting an area between the outer rolling groove and the inner rolling groove with the cylinder body, and a plurality of steel balls (36) that can roll within an endless circuit (35) formed of the cylinder body, the connection paths and the area between the outer rolling groove and the inner rolling groove, wherein the connection paths (34) are formed at a pair of inner members, i.e. return caps (33), disposed on the inner sides of metal end plates (12) that are attached to the front and rear ends in the sliding direction of a sliding body (4).

A plunger and cylinder assembly for the fluid end of a reciprocating pump. The assembly comprises a traveling cylinder, a stationary plunger, and an optional sleeve secured to the traveling cylinder in a detachable manner. The traveling cylinder is displaced along its axis by a thrust component and acts cooperatively with the stationary plunger to create a pressure change in the reciprocating pump.

A plunger and cylinder assembly for the fluid end of a reciprocating pump. The assembly comprises a traveling cylinder, a stationary plunger, and an optional sleeve secured to the traveling cylinder in a detachable manner. The traveling cylinder is displaced along its axis by a thrust component and acts cooperatively with the stationary plunger to create a pressure change in the reciprocating pump.

A piston unit of a working cylinder has first and second coupling partners. The first coupling partner is a piston. The second coupling partner is a piston rod. The piston rod is inserted axially into the piston. Each of the coupling partners has an annular groove, the groove of the piston rod is an external groove, the groove of the piston is an internal groove. The grooves of the coupling partners lie opposite one another. The unit has a spring-loaded coupling ring. The coupling ring, when deformed in a tensioning direction, is fully accommodated by the groove of one coupling partner and which, when deformed in a release direction, engages in the grooves of both coupling partners. The engagement of the coupling ring in the grooves produces a form-locking connection between the partners. The piston rod is oversized in relation to the piston and provides an additional frictional connection.

A piston unit of a working cylinder has first and second coupling partners. The first coupling partner is a piston. The second coupling partner is a piston rod. The piston rod is inserted axially into the piston. Each of the coupling partners has an annular groove, the groove of the piston rod is an external groove, the groove of the piston is an internal groove. The grooves of the coupling partners lie opposite one another. The unit has a spring-loaded coupling ring. The coupling ring, when deformed in a tensioning direction, is fully accommodated by the groove of one coupling partner and which, when deformed in a release direction, engages in the grooves of both coupling partners. The engagement of the coupling ring in the grooves produces a form-locking connection between the partners. The piston rod is oversized in relation to the piston and provides an additional frictional connection.

A piston assembly is provided for an unloader valve of an air compressor. The assembly comprises an unloader piston having a first bore of a first diameter, and a second bore of a second diameter which is smaller than the diameter of the first bore. The assembly also comprises a coil spring having a central opening, one end portion disposed in the second bore, and an opposite end portion extending into the first bore. The assembly further comprises a balance piston including a head portion sized to be disposed in the first bore, a first stem portion extending from the head portion and having a diameter smaller than the first and second bores, and a second stem portion extending from the first stem portion and extending into the central opening of the coil spring and having a diameter smaller than the first stem portion.

A piston assembly is provided for an unloader valve of an air compressor. The assembly comprises an unloader piston having a first bore of a first diameter, and a second bore of a second diameter which is smaller than the diameter of the first bore. The assembly also comprises a coil spring having a central opening, one end portion disposed in the second bore, and an opposite end portion extending into the first bore. The assembly further comprises a balance piston including a head portion sized to be disposed in the first bore, a first stem portion extending from the head portion and having a diameter smaller than the first and second bores, and a second stem portion extending from the first stem portion and extending into the central opening of the coil spring and having a diameter smaller than the first stem portion.