Abstract: A dual-piston pump apparatus includes a pair of reciprocating sleeves within which a pair of reciprocating pistons are disposed. The pistons and sleeves are each supported on a frame for independent reciprocating movement along a line angled relative to horizontal by an angle of less than about 60.degree.. The apparatus also includes a piston construction including a removable face which permits the piston to be broken down for cleaning. Each piston is normally restricted by a stop from extension beyond the end of the corresponding sleeve, but an actuator is provided for freeing the piston relative to the sleeve so that the piston may be extended beyond the sleeve and the sleeve may be withdrawn from a pump chamber of the apparatus.

Abstract: A ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.

Abstract: An ejection pump apparatus of a torpedo launching system is provided with improved water piston which is more stable during use and which enables the intake end of the water cylinder and the sea valve to have a smaller diameter than that of the piston. In order to assemble the piston through the smaller diameter opening, the piston is segmented into four pie-shaped segments which are assembled together in adjacent relation with bolt fasteners that extend through the sidewalls of the segments. The outer wall of the piston includes a circumferential slot which divides the outer wall into two spaced bearing lands which provide the piston with more stability. The circumferential slot also enable water to flow through the sidewall of the piston into the piston and outwardly through an open top thereof.

Abstract: In a piston with an encompassing seal, which is seated slidably in a cylindrical receiving bore of a structural part such as a housing block and which can be acted upon by pressure on at least one end, the piston is intended to have a shoulder for receiving the seal. This shoulder divides a cylindrical running face of the piston of a segment having a jacket face, and a groove is formed into the jacket face for receiving a ring that secures the seal in the axial direction and also acts as a stripper ring protecting the sealing ring.

Abstract: The improved aircraft brake piston cap assembly (40, 40') comprises an aircraft piston (10) having a pair of openings (46) extending through the piston (10) and a piston cap (42) with a flange (44) fitted around the circumference of the piston (10 ) and having a pair of openings (48) aligned with the openings (46) in the piston (10 ) . A safety wire (50 ) may extend through the openings (46, 48 ) and be wrapped about a portion of the circumference of the piston cap so that the ends (52) are intertwined (53) to retain the safety wire (50) in place and the cap (42) attached to the piston (10), or a solid or spring pin (60, 60') may be press fitted into the openings (46, 48) of one of the piston cap (42) and piston (10) to attach the piston cap (42) to the piston (10) . The improved piston cap assembly (40, 40') permits components within the piston (10) to be extended to axially longer dimensions, and provides an improved, efficient and reliable attachment of the piston cap (42) to the piston (10).

Abstract: A piston for an internal combustion engine has a crown and peripheral wall to carry a piston ring. A support extends between the wall and a bearing housing to receive the connecting rod. A cylindrical support member also extends from the wall around the support to a skirt. The support member is radially inset from the wall and a cylindrical bearing member is located on its radially outer surface.

Abstract: A ceramic-metal composite structure which minimizes tensile ceramic loads and accommodates differences in thermal expansion characteristics between a metal member and a ceramic member without reliance on precise feature control for either member. The composite includes a mechanical retainer which allows a loose fitting relationship between the metal and ceramic members. The ceramic member is secured within a receiving bore in the metal member by the retainer in a manner which eliminates the need for precise machining of the ceramic and metal members. The metal member may be configured to accept either an internal or an external mechanical retainer element. The composite ceramic-metal structure of the present invention finds particular utility in forming a durable wear-resistant interface in internal combustion engine actuator or actuating components, such as compression brake master pistons.

Abstract: A piston for forcing a liquid metal out of a casting cylinder of a die-casting press, having a mounting piece with an end surface and an outer peripheral surface; and a cap having an inner cover surface, an inner peripheral surface, and a free edge surface. The cap is mounted on the mounting piece so that the inner cover surface faces the end surface, and the inner peripheral surface has, proximate to said free edge surface, a plurality of notches formed therein. The outer peripheral surface has a plurality of bayonet-catch projections extending therefrom which are received in the plurality of notches.

Abstract: A piston for a door closer comprises metal cups on opposite ends of a stem. A plastics ring is a snap-fit in one of the cups and protrudes from that cup to seal against the wall of a cylinder. A groove in the side wall of the cup for receiving a rib on the ring is formed by pressing a substantially flat blank before the blank is formed into the cup.

Abstract: A metering pump wherein the head is provided with internal threads terminating adjacent to internal shoulders at each of the pump cylinder, inlet valve and outlet valve ports. The cylinder, inlet valve and outlet valve each include a flange secured to the shoulder by a collar threadably received in each of the ports. O-rings are provided in a circumferential groove in the body or cylinder of the pump inlet valves and outlet valves downstream of the flange. A piston pump structure includes a bushing mounted to the piston rod between the piston head and a second breakaway stop connected to the piston rod. The piston head includes a plurality of circumferential grooves for receiving respectively a cup seal or an O-ring seal. A suck-back mechanism is provided in a bore in the head and includes a stem having an eccentric cam which interacts with the valve structure to adjust the degree of closure by rotation of the stem.

Abstract: A cylinder without a piston rod comprising a cylinder, a piston for moving along the axial direction within the cylinder, and tension belt means for directing the piston witnin the cylinder. The piston comprises two piston halves which are interconnected by bayonet connection elements. A holding element is held within the piston halves for holding the ends of the tension belt means in place.

Abstract: Piston tops (1, 70), specially those provided with combustion chamber (2, 20) and ring zone (3, 30) have their cooling condition sensibly improved in such regions due to a better use of the cooling oil capacity by closing the cooling chamber (5, 50) and the region 2I under the combustion chamber by annular ring members (96, 13) in a resilient material, e.g., a polymeric material or, preferably a spring steel, which clamp under the cooling chamber (5, 50) and the region 2I with dimensional interference respectively with grooves (10, 100), notches (11, 110) and groove 15. Methods for the manufacture of such top portion having a reduced compression height are also described.

Abstract: A food pot for dispensing liquid foods includes a main body portion having a bottom and an upstanding sidewall, and a spout mounting portion formed on a lower portion of the sidewall. A spout is mounted on the spout mounting portion and is resiliently deformable, having an open spout end opposite a connecting portion which is connected to the spout mounting portion. The open spout end is in communication with the interior of the main body portion. A piston is slidably received within the sidewall of the main body portion, and is substantially hollow and includes a lower piston body portion and a lid portion, the lower piston body portion having a lower piston face and an upstanding piston sidewall. The upstanding piston sidewall has adjacent an uppermost end thereof a detachable attaching arrangement for removably attaching the lid portion to the lower piston body portion.

Abstract: The present invention relates to a high pressure piston sealing system. More particularly, the present invention relates to a sealing system adopted for rigorous marine applications which prevent or inhibit the use of a seal lubricant.

Abstract: A piston stem insert to be received within a hollow receptacle that is molded at the interior of a carpule based piston, so that a piston stem may be easily attached to and detached from the piston by way of the insert. In a first embodiment of the invention, a set of flexible, anti-displacement wings extend radially from the insert to releasable and frictionally engage the inside walls of a carpule, so as to prevent an inadvertent and premature displacement of the piston through the carpule. In a second embodiment, a set of anti-rotation wings extend radially from the piston stem insert to be received within respective cavities of the receptacle that are shaped so that the wings may be rotated in a single (e.g. clockwise) direction but blocked from rotation in an opposite direction.

Abstract: The present invention is a retainer for a piston and valve subassembly of a scotch yoke compressor and a method of assembling it. The subassembly is comprised of a piston head, a suction valve, a spacer, a stop washer, and a rod held together by a retainer. The suction valve is assembled on the rod, then the rod is inserted into the piston head. Next the retainer is installed on an end of the rod for frictionally engaging the piston and rod, thus axially securing the suction valve and the rest of the piston head subassembly during assembly to the yoke.

Abstract: The Assembly comprises a piston body having a longitudinal axis to which are added, in interlayered fashion, separate, piston-ring lands and spacers. In one embodiment, a pair of rider rings are coupled to the piston body, in spaced apart locations, to guide the piston assembly in reciprocation, and to space the piston-ring lands away from the surface of an enclosing cylinder. The lands have a diameter which is slightly less than that of the rider rings. The lands are formed of ceramic to offer, thereby, a substantially wear-resistant surface to the piston rings which are set between pairs of the lands, and about the spacers. The body is centrally bored and tapped, and the lands and spacers are centrally apertured; a headed bolt has the shank thereof in penetration of the lands, spacers and rider rings, and threadedly engaged with the tapped bore, to secure the assembly together.

Abstract: A plunger for forcing molten aluminum or brass out of a casting cylinder of a diecasting machine includes a cap which is screwed via an internal thread onto an external thread of a supporting body and is made of a material, in particular a copper alloy, which has a greater coefficient of thermal expansion than the material of the cylinder, in particular steel, and the material of the supporting body, in particular steel. An inner cover face of the cap bears against a front face of the supporting body and, with its internal thread, is screwed thermally onto the external thread of the supporting body, and in addition, is preferably shrunk on thermally.

Abstract: A piston and piston rod subassembly for use with a hydraulic damper is disclosed. The piston is formed from a substantially flat blank having a pattern of bendable tabs provided along a first edge. A bendable skirt is provided along a second edge of the blank. After the blank is formed into a cylindrical body, the tabs are crimped onto a flanged end of a piston rod. A valve assembly can be retained in the cylindrical body by crimping the skirt over the valve assembly.

Abstract: A piston for an hydraulic brake is of the kind comprising an insulating core member and a cup member, joined together by fastening means arranged between the core and cup members.This fastening means is constituted as follows. The base portion of the cup member has a central projection, while the core member has a central cavity which is open at the level of the outer projecting surface of the cup member and which is closed by an end wall forming the base of the cavity, with the projection from the cup member base portion extending through a hole in this base wall. An axially acting resilient means is engaged on the free end of the projection within the cavity and engages against that face of the wall which is directed away from the base portion of the cup member. The invention is particularly applicable to the control of hydraulic brakes, in particular for automotive vehicles.

Abstract: A connecting structure for a rod in an outboard motor includes a rod having an end forced in a piston, and a stopper ring disposed between the rod and the piston.

Abstract: In a piston for piston machines comprising a hollow body, open at least at its free end, having an axial cavity in which there is a filler piece at least partly filling the latter and consisting of a material of lower specific gravity than the material of the piston, said filler piece being secured in the cavity and being held axially in the cavity by a locking element arranged at the free end of the hollow body and a spring arranged between the locking element and the filler piece, the filler piece is inserted axially and the axial securing and locking is effected solely by the spring, which is pretensioned by the locking element to such an extent that it acts against the filler piece with a spring force greater than the maximum inertial forces of the filler piece acting against the spring to be expected when in operation.

Abstract: The invention relates to the dry run-high pressure stage of a multistage piston compressor with a piston designed as a tappet (2) guided in the high pressure cylinder (1) and sealed against the compression space of the cylinder (1) by means of self-lubricating sealing elements (3) forming an annular gap together with the working surface, whereby the latter is formed by a material suitable for dry run. According to the invention, the sealing elements having a height conforming at least to their diameter are embodied in the form of at least two cylindrical sealing elements (3), which are loosely placed one on top of the other in the cylinder (1) on the free end of the tappet (2), provided with working surface guides at least in part areas, and have chamfers (6) on the face side.

Abstract: An impact tool including a cylinder, a piston slidably mounted in the cylinder and a valve for selectively opening and closing oil feed channels to move the piston up and down. A cylindrical member is slidably mounted on the piston around its large-diameter portion or thereunder. Its bottom end defines the top end of a lower chamber formed in the cylinder. The cylindrical member is adapted to descend together with the piston. But when the piston strikes the object and rebounds upwardly, the cylindrical member keeps descending away from the piston owing to the inertia force. Thus the volume of the lower chamber is kept from increasing excessively after the piston has struck the object. This will prevent cavitation in the lower chamber. When thereafter the lower chamber communicates with the oil feed port and pressure oil is fed thereinto, the cylindrical member will be pushed up toward the large-diameter portion under oil pressure in the lower chamber.

Abstract: A piston assembly for a shock absorber comprises a piston rod which is formed with a threaded opening which extends axially and opens to an axial end, about which a piston body is mounted. A stud which is separately formed and independent of the piston rod, and extends through the piston body, engages with the threaded opening for securing the piston body thereonto.

Abstract: In a compressor which has a connecting rod comprising: a second eye (31) connected to the crank pin (12) and a crankshaft (7) and including a radial projection (32) with a longitudinal slot (33), said longitudinal slot (33) having at least two end faces (35) and two opposite lateral faces (34);a first eye (21) connected to the piston and including a rod (22) with an end portion, said end portion having at least two end faces (25) and two opposite lateral faces (24), said end portion being fitted in said longitudinal slot (33) so as to bring the end faces of the slot (33) and the rod (22) into contact therefore defining the axial distance between the centers of the eyes.According to the invention a clamp (40) preferably of spring steel, is fitted in the housing (28, 29, 38, 39) of the radial projection (32) of the second eye (31) and the end portion of the rod (22).

Abstract: A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

Abstract: A piston head and rod assembly for use, for example, in a gear pump dry valve is disclosed. A cylindrical piston head is provided with a generally oval-shaped cavity formed therein which defines a minor diameter. The cavity opens through one end of the piston head. However, a portion of the opening is blocked by a radially inwardly-extending lip. The lip defines an opening diameter which is smaller than the minor diameter of the cavity. An end portion of a piston rod includes a reduced diameter neck portion and an enlarged diameter tail portion. The neck portion has an outer diameter which is slightly smaller than the opening diameter defined by the lip, while the tail portion has an outer diameter which is slightly smaller than the minor diameter defined by the cavity. To assemble, the tail portion of the piston rod is inserted through the portion of the opening of the piston head which is not blocked by the lip into the cavity.

Abstract: A sealing device particularly suitable for sealing pistons of working cylinders and for sealing two machine components which can slide against one another is disclosed. A conventional sealing element consisting of low-friction, but not very elastic material, such as PTFE plastic material, and resting on an elastic support, is used. The cross-section of the sealing element in a direction of the sliding motion is U-shaped and encircles the support. The dimensions of the support and the sealing element are determined such that the support exerts prestress forces on the sealing element which try to bend the rim areas of the sealing element outward against the sliding surface for the sealing element. Consequently, an additional force component, directed toward the sliding surface, results for the pressure force which is exerted on the sealing element by the support and functions as a sealing force.

Abstract: A brake arrangement, especially a disk brake for vehicles, includes a brake caliper with brake pads guided on both sides of a brake disk which are operatively connected with hydraulically actuatable actuating pistons. Each actuating piston includes a bore directed toward the brake pad in which is arranged a cylindrically shaped insert number that includes a flange covering the piston end surface and is held with a radial and axial play with respect to the inner circumferential and bottom surface of the bore.

Abstract: A rod-piston connection uses a split ring, having two or more segments, provided with a plurality of shallow internal grooves which are adapted to mate with a corresponding plurality of shallow grooves on the piston rod, the outer periphery of the split ring having a tapered surface extending over the entire width of th split ring and adapted to mate with a corresponding wide tapered surface defined in a bore of a compression bushing which has a peripheral surface provided with threads which engage with an internal threaded surface in a cavity in the pistion. By applying a threading torque to the compression sleeve, a force is generated by the two tapered surfaces to force the compression sleeve into better contact with the pistion and to force the split ring into a better contact with the piston rod.

Abstract: A peristrophic internal combustion engine with increased power output has greater torque and reduced friction. The distance of rotation between the inertia weights and the crankpins is increased to increase torque. These transposed inertia weights are embodied in top and bottom journals of the connecting rods and in the pistons assemblies. Each piston assembly includes a top piston-ring-holder piston and a lower, bearing piston joined to reciprocate in the cylinder. The lower bearing piston may have a circumferential ring, cylindrical barrel rollers, or spherical ball bearing arrangement contacting the cylinder wall while the upper piston carries the piston rings. The spherical ball bearing arrangement allows lower piston rotation about the piston axis. Inner and outer cylinder liners increase the cylinder operating life and reduce combustion heat loss through the cylinder wall.

Abstract: A method of repairing an end-of-car cushioning device for railroad cars is disclosed. The cushioning device is of the type having a piston and a shaft connected to the piston. In such devices, the shaft may become damaged with wear. In the disclosed method of repair, the old piston and shaft are removed from the cushioning device. The old shaft is substantially removed from the piston. The piston's true center is found, and a bore is cut through it. The bore is threaded, and an angled chamfer is cut in one end of the bore. A new shaft is provided with a threaded portion, the threads being adapted to mate with the threads of the bore. The shaft also has an angled chamfer adapted to mate with the bore's chamfer. The new shaft is connected to the old piston so that the threads engage and the chamfers abut.

Abstract: Fluid actuator includes a piston rod comprised of a wound filamentary composite structure to provide an extremely light weight, relatively low cost, envelope efficient design. Attached to the piston rod are one or more non-integral piston heads which are preloaded against one or more ramp surfaces on the exterior of said piston rod. A pair of oppositely facing ramp surfaces may be formed on the piston rod by interspersing filler means between the piston rod fiber layers. Another ramp area may be formed by providing an external groove in the piston rod which is engaged by longitudinally split support shoes that provide an attachment surface for a detachable piston head. An internal ramp may also be provided on the inner diameter of the piston rod adjacent the axial outer end thereof for mating engagement by a conically ramped exterior surface on an internal metal stud used to attach a rod end assembly to the axial outer end of the piston rod.

Abstract: A pump plunger formed from a centrally bored cylinder of a preferred compound having counterbored ends provided with inwardly converging counterbore inner end limits for thermally shrinking and centering a bolt and its nut therein. One end of the bolt projects beyond the cylinder and is threadedly connected axially with a plunger mounting shaft. The cylinder is turned concentric with the mounting shaft.

Abstract: Disclosed is a single acting mud pump piston assembly adapted for use in a mud pump mechanism including a piston and having an end portion with a shoulder reciprocatingly mounted in a cylinder. The assembly includes a circular flange mounted on the end portion in abuttment with the shoulder. A hub is removably mounted on the end portion in abuttment with the flange. A piston cap is mounted about the hub in abuttment with the flange. The assembly is held together by a washer and a nut engaging the end portion.

Abstract: A shaft alignment system for pumps which utilizes a clamp for holding a reciprocating shaft to a piston in an abutting relationship. The clamp can be loosened and retightened after the piston, which is attached to the reciprocating shaft, is inserted in a cylinder. Forces induced on the piston after insertion in the cylinder cause the piston and shaft to be realigned. Resecuring the reciprocating shaft assembly to the piston assembly causes the system to be precisely aligned in a transverse direction.

Abstract: An improved piston for operation within a cylinder. The piston includes a main piston body having a primary cylindrical surface, a first end, and a secondary surface of smaller diameter, the secondary surface of smaller diameter is disposed between the primary cylindrical surface and the first end. At least one piston ring is disposed and captured in an operational position about the secondary surface of the piston body by a releasably mounted cap positioned on the first end of the piston body.

Abstract: In a cable-cylinder type hydraulic elevator there is provided a piston and cable termination assembly that makes possible the removal and replacement of seal means and/or bearing means without the necessity for either disturbing the cable termination inside the cable socket member or cutting the cable and making a new termination.

Abstract: A rack-and-pinion steering gear structure for a vehicle including a rack housed within a cylinder and driven by means of a pinion shaft, comprises an annular piston received with suitable axial clearance in an annular groove defined by three surfaces, namely the end face of one end of the rack, a seating surface of a head of a bolt screwed into a boss projecting from the end of the rack, and the outer periphery of the boss itself. An elastic annular seal member is interposed between the inner periphery of the piston and the outer periphery of the boss.

Abstract: A hydraulic door closer has a housing including a bore and a piston supported for reciprocal sliding movement within the bore in door opening and closing directions corresponding, respectively, to opening and closing movements of an associated door. The piston has a head at one end and an open opposite end which receives a portion of a spring which biases the piston in its door closing direction. First and check second check valves within the head comprise part of a fluid control system for checking movement of the piston during at least a portion of its travel in either its door opening or door closing direction.

Abstract: A piston (2) is of refractory materials, particularly for a compression-ignition engine of the type having a head (4), a skirt (6) and their mutual fastening means. According to the invention, this skirt (6) is formed entirely of a refractory material and has two semicylindrical parts (18, 20) each of which has ribs (22) and a semispherical cavity (36, 38). After assembly, the cavities form a ball joint seat for the small end of a piston rod along a plane containing the longitudinal axis (14) of the piston (2). Application is to compression-ignition engines with high efficiency.

Abstract: A rotary actuator having a cylindrical housing in which an annular piston arm rotates through an arc within an annular chamber in the housing as a result of fluid pressure to produce rotary motion communicated from the piston to the drive shaft. The piston head is capable of lateral or radial movement relative to the piston arm so as to accommodate flexing of the piston arm or variances in the shape of the chamber. Friction reduction washers are placed between the piston head and the piston arm to facilitate this movement. The overall effect is to reduce the friction encountered by the piston head against the walls of the chamber during movement, thereby improving overall performance of the actuator.

Abstract: A multi-part plunger piston for internal combustion engines, comprises a piston upper part and lower part which engage one on the other through coinciding annular abutment surfaces. The parts are connected with one another by screws which pass through the annular surfaces. At least one of the annular abutment surfaces is domed in the circumferential direction in such a way that the annular surfaces are more strongly resiliently braced in the region between the screws in the finally assembled piston than in the regions around the screws. Due to the elastic initial stressing of the regions of the annular abutment surfaces between the screws it is intended reliably to avoid lifting away of the annular abutment surfaces in these regions during engine operation. When the finally assembled piston is in the cold condition the annular surfaces lie uniformly against one another over the entire circumference, admittedly with locally differing initial stresses.

Abstract: A piston drive for use in diesel engines with a high specific liter output wherein the piston comprises discrete sealing and guiding sections and is constructed, configurated and assembled in such a way that the flow of power from the combustion zone takes place along straight paths directly from the crown to the connecting rod without causing any bending and/or other deformation of component parts of the drive. The piston drive allows for achievement of higher output, without increasing the stroke volume of the cylinder, by using relatively inexpensive piston sections and without reducing the E of the engine.

Abstract: A hydraulically controlled brake is equipped with a device preventing an excessive rise in temperature of the hydraulic fluid. The control piston of the brake comprises a cup-shaped piece and also an insulating core accommodated in the cup and having a free end face via which the piston pushes on the friction element. The core is screwed onto a central threaded column projecting from the bottom of the cup.

Abstract: To prevent distortion of the cylinder, and free running of the motion transfer element (6) thereon, in guide tracks (12) formed on the outside of the cylinder, the piston (5) is formed in two piston parts (22, 22') connected by a piston rod or pin (26, 26', 26a, 26a', 26b, 26b', 26c, 26c', 26d, 26d'), and the motion transfer element (6) is coupled to the piston rod or pin by a pair of fork-like portions (20) surrounding the pin and permitting limited radial movement. The pin or piston rod may be somewhat flexible, or made of flexible material, for example unitary with the piston parts (22, 22') and of plastic material, or may be made in two portions or parts (22, 22'; 22a, 22a' . . . ), each individually coupled to the fork-shaped element or merely retaining the fork-shaped element in position with end shoulders (25, 25') of the piston part axially engaging the fork-shaped element and hence transferring motion to the motion transmitting element (6).

Abstract: A triplex plunger pump for liquid cryogen service includes a power end frame comprising a casing formed of welded plate sections and elongated tubular members interconnected to form a main bearing support structure which minimizes the transmission of pump reaction forces to the casing outer walls. The power end frame is provided with removable guide sleeves for supporting respective cylindrical crossheads. The sleeves are retained in the power end frame in bores formed in spaced apart support plates. The crank or eccentric shaft is a multipart assembly including a cylindrical shaft having spaced apart splined sections which are interfittingly engaged with splines formed on removable eccentrics. The shaft main support bearings and the eccentric bearings are cylindrical roller bearing assemblies.

Abstract: A rodless cylinder having a piston and an operation member slidable along the outer circumferential surface of a cylinder tube, each mounted with permanent magnets, and adapted to move the operation member along the cylinder tube by utilizing the attraction force between these permanent magnets, in which a plurality of individual magnets disposed axially to the cylinder in each of driving and driven magnet rows are arranged such that identical poles of the individual magnets are in adjacent to each other, and both of the driving and driven magnet rows are arranged such that the different poles of the individual magnets in each of the magnet rows are opposed to each other can provide a greater attraction force between the magnet rows with no changes in the size of the magnet and thereby reduce the size of the entire apparatus.

Abstract: A piston for a fluid pressure chamber having an arcuate longitudinal axis. Such piston comprises an assemblage of two spherical bodies in side-by-side relationship and interconnected by a universal pivot. Each spherical body carries a circumferential piston ring receiving groove and piston rings are mounted in such grooves to provide a sliding and sealable engagement with the walls of the fluid pressure chamber as the piston moves along the curved longitudinal axis of such chamber.