Abstract: A piston for use in an internal combustion engine having a two-piece construction including an upper and a lower part. The upper and the lower parts include one or more overlapping cutouts to reduce the weight of the piston. One or more of the cutouts or connecting walls include wall regions that transition to adjacent walls without sharp or abrupt areas. The piston upper and lower parts are permanently joined together. One or more tongue and groove structures are used to provide a locking connection between the piston upper and lower parts.

Abstract: The invention relates to a die casting ring (1) internally fitted with radial teeth (11) to be engaged into matching seats (22) provided on a piston (2). This piston-ring assembly prevents mutual rotation or axial translation, in addition to ensuring an optimal seal against infiltration of liquid metal during the die casting process. When the ring has a cutout (10), it can be mounted accurately onto the piston because the teeth (11) allow the cutout to be positioned anywhere relative to the piston.

Abstract: A piston including a crown and a skirt extending generally axially away from the crown. The skirt includes a pair of opposed skirt panel portions and a band spaced away from the crown and extending generally around a perimeter of the piston. The piston further includes a pair of strut assemblies, each strut assembly including a pair of struts which converge in a radially outward direction. Each strut terminates at or adjacent to one of the panel portions.

Abstract: The invention relates to a two-part piston (1) for an internal combustion engine, consisting of an upper part (2) and a lower part (3) which is screwed to the upper part. The upper part (2) and the lower part (3) are in contact with each other, partially by means of inner bearing surfaces (25, 26) defining the lower side of an upper ring rib (10) and the upper side of a lower ring rib (11), and partially by means of outer bearing surfaces (28, 29) defining the lower side of the ring wall (9) and the upper side of a collar (27) applied to the lower part (29). In order to avoid frictional rubbing, frictional heat sealing and pressure-related material heat sealing, at least one of the bearing surfaces (25, 26, 28, 29) is easily and economically provided with a chrome layer (30) which has a structured surface comprising a plurality of raised parts and recesses.

Abstract: Exemplary power cell assemblies and methods of making the same are disclosed. An exemplary power cell assembly may include a piston crown and connecting rod. In an exemplary illustration, a power cell assembly includes a piston crown having a ringland extending circumferentially about a combustion bowl. The boss portions may each include inwardly extending shoulders defining arcuate crown running surfaces. The power cell assembly may further include a connecting rod having a shank and an upper end received in a cavity of the crown. The upper end of the connecting rod may define arcuate connecting rod running surfaces extending away from the shank. The crown running surfaces and connecting rod running surfaces generally allow the connecting rod to pivot with respect to the piston crown about an axis of rotation that extends from one of the boss portions to the other of the boss portions.

Abstract: A method for screwing together two metal parts that are spaced apart from one another close to a screw connection element and elastically deformable relative to one another, and for the remainder lie against one another. In order to obtain a firm and secure screw connection, with little expenditure of torque, one of the metal parts is deformed, before the metal parts are screwed together, in such a manner that regions close to the screw connection element come close to one another, and the metal parts are then screwed together. A region of the one metal parts remains deformed after they have been screwed together, as a result of the screw connection element.

Abstract: A two-part piston for an internal combustion engine has an upper part that has a pin having an outside thread on the underside of its piston crown, and has a lower part that has a crown part, onto which an expansion sleeve that can stretch elastically in the axial direction is formed, radially on the inside. A pin is introduced into the sleeve in order to screw the upper part to the lower part. The expansion sleeve is stretched in the axial direction. In order to improve its strength, the material of the expansion sleeve has a higher stretching limit as compared with the rest of the piston material. The increase in the stretching limit is achieved by permanent stretching of the expansion sleeve in the axial direction, by approximately 1% of its length.

Abstract: A two-piece piston for an internal combustion engine has an upper piece and a lower piece, the lower piece having an upper base part with an opening lying coaxial to the piston axis into which a pin on the upper piece is inserted. The upper piece is connected to the lower piece with a hexagonal nut screwed onto the pin. A resilient sleeve is arranged between the upper piece and the lower piece comprising an inwardly directed collar on the against which the upper face of the hexagonal nut lies and in the region facing away from the piston crown, a contact surface facing the piston crown lying on a surface on the inner side of the opening. An economically produced two-piece piston results with a resilient sleeve between both screwed piston pieces which exerts a pre-tensioning and thus provides security for the screw connection.

Abstract: The invention proposes a liquid-cooled assembled piston (1) having an upper part (2) and a lower part (3), wherein the upper part (2) and the lower part (3) are connected to one another by means of a radially outer annular support (12) and by means of a radially inner annular support (11). An outer cooling duct (13) is arranged between the outer support (12) and the inner support (11), and an inner cooling duct (18) is arranged radially within the inner support (11). Here, the outer cooling duct (13) is connected to the inner cooling duct (18) by means of at least one overflow duct (22, 22?).

Abstract: A two-piece piston for an internal combustion engine has an upper piece and a lower piece, the lower piece having an upper base part with an opening lying coaxial to the piston axis into which a pin on the upper piece is inserted. The upper piece is connected to the lower piece with a hexagonal nut screwed onto the pin. A resilient sleeve is arranged between the upper piece and the lower piece comprising an inwardly directed collar on the against which the upper face of the hexagonal nut lies and in the region facing away from the piston crown, a contact surface facing the piston crown lying on a surface on the inner side of the opening. An economically produced two-piece piston results with a resilient sleeve between both screwed piston pieces which exerts a pre-tensioning and thus provides security for the screw connection.

Abstract: The invention relates to a split piston for an internal combustion engine, comprising an upper piece, connected to a lower piece, by means of a screw connection. The screw connection comprises a tubular connector piece, mounted on the underside of the piston upper piece with an external thread, a spacer sleeve with an external and an internal thread and a support rib formed on the lower piece of the piston with an internal thread. The upper piece can thus be screwed to the lower piece, by means of the connector piece, the spacer sleeve and the support rib. The spacer sleeve acts as a compressing body and the connector piece as an extending body, to generate the mechanism tension necessary for fixing the screw connection.

Abstract: Proposed is a two-part piston 1 for an internal combustion engine, having an upper part 2 that has a pin 31 having an outside thread 32 on the underside of its piston crown 4, and having a lower part 3, which is connected with the upper part 2 by means of a nut 29 screwed onto the pin 31. The lower part 3 has an elastically resilient upper base part 25, onto which an expansion sleeve 26, elastic in the axial direction, is formed, which has an opening 27 having a collar 28, which is directed radially inward, into which the pin 31 is introduced. An elastic compression sleeve 30 is formed onto the nut 29, which sleeve rests against the collar 28. In this connection, the elastic resilience of the base part 25, the expansion sleeve 26, the compression sleeve 30, the pin 31, and the piston crown 4 has the result that the screw connection has a flat characteristic line despite a low compression height of the piston 1, thereby imparting great strength to the screw connection.

Abstract: A piston for an internal combustion engine, comprising a piston head (2) and at least one cooling chamber (4) that can be supplied with oil and is arranged underneath the head (2) of the piston, whereby the lower limit of the cooling chamber is formed by a sheet of metal that can be elastically deformed and is fixed to the piston. The objective of the invention is to enable the metal sheet (6) to be fixed in a simple manner. This is achieved by using components that are subjected to pressure, pressing the elastically deformable sheet of metal (6) against projections that are located at a height corresponding to approximately half way up the hub supports in the direction of the piston head (2).

Abstract: A piston (20) for an internal combustion engine includes an upper crown (22) and a lower crown (24) that are each fabricated using a same strong material, such as steel and fastened together using a plurality of fasteners (50). The piston (20) provides increased strength resulting in improved design flexibility and smaller sized engines that produce the same amount of power. Piston ring grooves (100, 102, 104) are also provided in either one or both of the upper and lower crowns (22, 24) which control piston combustion height. A deeper combustion bowl (72) is also available with the piston (20).

Abstract: Disclosed is a clamping device for a piston to be mounted, said clamping device being actuated mainly in the direction of pressure/counter-pressure, whereby the whole initial pressure is increased, resulting in greater anti-loosening safety. To that end two screws are placed very close to each other on each side of the piston, one pair being on the pressure side of the piston and the other pair on the counter-pressure side. Both screw pairs have on each side a common pressure member.

Abstract: An internal combustion engine component assembly including piston, wrist pin, and cylinder sleeve, all constructed of a matching carbon-carbon composite is disclosed. The piston is a two-piece assembly divided in crown and skirt, each fabricated individually to optimize the most desirable properties in the respective cylinder areas in which they operate. The crown is fabricated by placing the fiber and binder into a compression mold and pyrolizing(heating) the resulting preform at a high temperature in the range of 1500 to 2000 degrees C. to achieve high temperature strength, and high thermal conductivity that continue after machining to the finished crown part. The skirt, a separate piece, on the other hand is fabricated differently to seek higher lubricity and better wear resistance along the cylinder wall with lower thermal conductivity to minimize heat loss.

Abstract: A piston assembly including a piston having a work surface, a sidewall extending from the work surface, and ports in the sidewall. The piston assembly also includes a flexible lubricant-scraping ring clamped to the piston between the work surface and the ports, with the lubricant-scraping ring having an outer edge extending outwardly beyond the sidewall.

Abstract: In a piston-cylinder assembly with a shaftless piston, the aim is to improve the lateral guidance of the connecting rod, to reduce edge wear and the seizing tendency in the event of fault during the combustion process. Consequently, the piston has at least one supporting ring, form-fittingly on the bosses which guides in the cylinder the piston along with the piston head.

Abstract: Piston unit for an internal combustion engine, especially for a large diesel engine, comprising at least three main parts located in successive order in the direction of the longitudinal axis of the piston and to be connected to each other. The piston unit includes a uniform upper part (3), which defines, when installed within a cylinder of the engine, a combustion chamber from the side of the piston and which is fixed inside of the piston at its central region to a middle part (2) of the piston unit preferably by means of a screw (4) or the like. At least the main part of, preferably all of the piston ring grooves (7) are arranged on a middle part (2). In addition the upper part (1) is selected to be of a material with better heat resistance than that of the middle part (2) and of a lower part (1).

Abstract: A vacuum pump is provided with at least one cylinder having a cylinder liner and a piston mounted for reciprocating movement within the cylinder liner. The piston is connected to a crankshaft for reciprocating the piston and the piston is provided with a piston head having a flat face and an upper end thereof. A valve plate having a flat surface facing the flat surface of the piston head is biased into engagement with the end of the cylinder liner whereby upward movement of the piston the flat face of the piston head makes full contact with the flat face of the valve plate to move the valve plate away from the cylinder liner. The piston is provided with two annular lip seals having an L-shaped configuration disposed in opposite directions at opposite ends of the piston in engagement with the cylinder liner.

Abstract: The invention provides a pump comprising at least one piston (26, 28) movable in a reciprocating manner within a chamber (12), sealing means (32a, 32b) located between the piston (26, 28) and the interior wall of the chamber (12), and venting means (36) for venting a portion of the chamber (12) bounded by the interior wall, the piston (26, 28) and the sealing means (32a, 32b), wherein the venting means (36) incorporates pressure regulating means (40) such that the pressure to which the said portion of the chamber (12) is vented can be regulated. This reduces the pressure differences across the or each sealing means and thus reduces deterioration and damage.

Abstract: The design and construction of past piston pin assemblies includes a retaining device which adds stress concentration factors to the piston pin assembly, piston skirt or piston crown. The present invention provides a device for retaining the piston assembly to the connecting rod and retaining the two parts of the piston pin assembly together without adding a stress concentration factor. The device uses a retaining means which applies a compressive force along the entire piston pin to add rigidity to the piston pin assembly. This design additionally allows for a stronger piston assembly with greater pull apart resistance and/or a lighter total weight piston assembly.

Abstract: The design and construction of past piston assemblies having a wrist pin bolted to a connecting rod had excessive structural components requiring more complex machining procedures and tooling. Additionally, the loading and bolting patterns allowed the wrist pin to flex about the central axis of the piston assembly causing ultimate failure of the design. The present invention overcomes these problems by providing a piston assembly utilizing a bifurcated connecting rod and a piston having a pair of outer legs and a central leg. The outer legs and the central leg contact a wrist pin in three locations substantially distributing the forces across the wrist pin uniformly. A connecting means centrally connects the piston assembly shortening the overall length of the piston assembly. This results in a simplified forging or casting process, a more easily machinable piston, and a higher reliability design with improved load capacity.

Abstract: An internal combustion engine piston assembly is provided wherein the underside of the piston has planar load bearing surfaces disposed perpendicularly to the axis thereof and the ends of the piston pin are provided with mating planar surfaces for fastening the pin to the underside of the piston head. The piston pin further includes a cylindrical bearing surface disposed between the ends for connection to the connecting rod.

Abstract: A novel prefinished piston pin insert bearing is described wherein the tight radial clearances required for acceptable bearing function are maintained in spite of the tolerances required for assembly through a unique inner bearing surface geometry and through a unique methodology of bearing retention against axial and rotational movement. The interior bearing geometry is formed of radii equal to that of the piston pin which are offset vertically into the upper and lower bearings and of radii of nonspecific size which are offset horizontally. The bearings are retained against movement through connections with the piston head, the piston skirt, and between the various bearing pieces. Means are also provided for feeding oil under pressure to the piston pin and bearing interface for lubrication and to the piston assembly for cooling.

Abstract: A split piston in an internal combustion engine, having a base rockably secured to the connecting rod, and a detachable ring head which interfaces with the cylinder wall. The detachable ring head is snugly fitted onto a cylindrical extension of the base having an axis parallel to the cylinder walls, to allow removal on the head without removal of the engine crankshaft or connecting rod. The snug fit minimizes combustion gas losses and eliminates to need for gas tight seals, while allowing removal of the head. Threaded fasteners are used to secure the head to the base.

Abstract: Pistons are described comprising a crown portion and a skirt portion, the crown portion having depending from the underside thereof a boss, the boss having secured thereto at least two bearing members in fixed relationship to the piston body and which bearing members co-operate with an associated connecting rod. The bearing members may be located in rebates in the boss such that piston firing loads are born substantially in compression. The bearing members are in one embodiment secured to the boss by a bolt and nut. The bearing members may comprise ferrous, copper-based or aluminium based alloys depending upon the application environment.

Abstract: A hydraulic cylinder, piston and rod assembly wherein the piston is secured to the rod in an efficient and inexpensive manner. The piston includes a threaded interior which is secured to a corresponding threaded portion on the end of the piston rod. An opening through a portion of the piston is aligned with a recess within the end portion of the piston rod to permit the insertion of a locking pin into the aligned openings. Thereafter, a compression ring, which is pivotally attached to the locking pin, is slipped into a complementary groove that is provided on the exterior periphery of the piston end portion. This provides a positive connection between the rod and piston which tolerates dimensional variations and eliminates play.

Abstract: An actuator for a hydraulically actuated caliper disc brake having a brake shoe comprises an actuating piston of two-part construction mounted for displacement in a cylinder and acted upon by a pressure fluid. The actuator has a cup-shaped member of cast steel, the bottom of which is acted upon by the pressure-fluid, and a cylindrical core of a mechanically resistant and heat insulating material removably coaxially and having an end face pressed against the brake shoe when actuated. A plurality of thin discs of mechanically resistant material are secured to the end face of the core adjacent to the brake shoe for reducing heat transfer from the brake shoe to the piston.

Abstract: The height of a piston for an internal combustion engine is reduced by the provision of gudgeon pin bores which intersect or at least partly intersect a ring band extending around the crown. This allows the mass of the piston to be reduced and allows improved visibility from the vehicle owing to reduced bonnet height. The weight of the piston is reduced so improving its performance and the performance of the engine.

Abstract: A piston machine, particularly a hydraulically-actuated piston machine, comprises at least one cylinder having an axis, a piston axially slidable in the cylinder and having a piston bottom with an inner surface, a piston rod turnably connected with the piston and having a piston rod shaft, a turning member mounted on the piston rod and having a side which is opposite to the piston rod shaft and has a convex circular surface, a pressing member having a shell surface which is in sliding contact with the circular surface of the turning member, the pressing member having a side which is opposite to the turning member and is provided with a convex circular surface abutting against the inner surface of the piston bottom, the circular surface of the pressing member and one of the circular surfaces of the turning member and the shell surface of the pressing member having central axes with central axes projections along their common orthogonals forming an angle of approximately 90.degree..

Abstract: An engine part and a method of producing the same are disclosed. The engine part includes a ceramic member, a metallic member secured to the ceramic member, and a metallic engine part body fixed to the metallic member, wherein the outer peripheral portion of the metallic member has a diameter smaller than the outer diameter of the ceramic member and is provided at one end facing the ceramic member with an annular notch. The engine part is produced by securing the ceramic member to the metallic member through fitting or joining and then fixing the metallic member to the metallic engine part body through fitting or screwing.

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 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 for a reciprocating piston internal combustion engine, in which the piston top (11) is secured to the wrist pin (14) by way of two support bearings (18) independent of the piston skirt (12). The piston ring carrier (16) connected with the piston top (11) is additionally connected with the two support bearings by way of a ring-shaped support element (19). A piston with a piston top (11) results which is capable of resisting high combustion space pressures.

Abstract: A piston for an internal combustion engine comprising a piston body (1) and a crown portion (3) that are connected by anchoring means comprising elongate members (7,23,26,79,80) that extend from the crown portion (3) into the piston body (1) so as to transmit tensile and compressive loads from the crown to a portion of the piston body in a region spaced axially away from the crown portion at a temperature which, at maximum operating temperatures, is low enough to prevent loosening of the anchoring means, characterized in that co-operating surfaces of said anchoring means (7,9,16) and piston body (1) are pre-loaded into contact with one another by virtue of mechanically applied strain energy stored in the anchoring means and piston body (1) and which acts axially to prevent parting of said co-operating surfaces by said tensile and compressive loads without being dependent on any reaction forces between the adjacent faces of the crown portion and piston body.

Abstract: A piston bottom for large capacity internal-combustion engines is made by forging a saucer-shaped blank from refractory-forging steel and then in a second forging step transforming the saucer-shaped blank into a cup configuration with a planar rim of the blank being transformed into a cylindrical shoulder and an annular bulge of the blank being transformed into an annular boss for connecting the piston bottom of the cylindrical body of the piston. The blank has a convexity projecting on one side of the blank opposite that formed with the bulge.

Abstract: An improved heat insulated piston assembly for an internal combustion engine and a method of assembly. The improved piston assembly includes a piston constructed of a sleeve having an interference fit about a heat insulated core. The core has a first end positioned flush with an end of the sleeve and has a second end located within the sleeve with a concave configured cavity formed therein. Mating in the concave configured cavity of the core is a connecting rod having a spherical ball shaped end. The spherical ball shaped end is securely held in the cavity by a retaining ring which attaches to the piston sleeve. The retaining ring allows for limited movement of the spherical ball shaped end of the connecting rod in the cavity while providing a means for returning the piston to its bottom position during the intake stroke.

Abstract: A piston assembly for an internal combustion engine having a rotatable crankshaft. The piston assembly includes a piston body having a concave configured cavity formed in one end and a plurality of recesses formed in its outer circumference. The piston body is connected to the crankshaft by a connecting rod having a spherical end which mates with the concave configured cavity. The connecting rod is secured to the piston body by an annular skirt which is attached to the piston body by a plurality of bolts. The bolts thread into retainers which are positioned in the recesses formed in the piston body.

Abstract: A composite piston for internal combustion engines having a lower part and an upper part composed of ferrous material and joined together by a centering screw-threaded ring, is provided with the screw-threaded ring which comprises internal screw threads adjacent the lower rim thereof and an internal annular rib adjacent the upper rim thereof, the lower part of the piston has a corresponding annular recess adjacent its upper rim configured to enable the screw-threaded ring to be screwed onto the upper rim of the lower part of the piston and the upper part has an annular recess in the upper rim thereof configured to receive the internal annular rib, when the screw threaded ring is screwed onto the lower part, with the axially extending and radially extending boundary surfaces of the internal rib forced against the confronting boundary surfaces of the annular recess of the upper part.

Abstract: Piston for internal combustion engines having a piston body consisting of light metal and a crown plate consisting of a metal of lower thermal conductivity which is secured axially to the piston body by means of necked-down screws and centered radially in relation to the piston body by means of an annular fit, and in which the outer ring of the fit is formed by the crown plate in the region of the sliding surface and the inner ring of the fit is formed by the piston body, in which at room temperature a gap widening in the direction towards the piston foot is provided between the annular surfaces of crown plate and piston body meeting in the annular fit, in such a way that the annular surfaces lie firmly against one another only at their ends pointing towards the piston head, and that this gap is reduced at working temperature.

Abstract: An internal combustion engine comprises a piston having first and second coaxial parts movable axially relative to each other in the direction of reciprocation of the piston and having a chamber therebetween which varies in volume with the relative movement. A conduit for fluid connects the chamber to a lubricant opening on a crank pin of a crankshaft. An inlet rotary valve between the lubricant opening and the chamber permits a flow of pressurized lubricant from the opening to the chamber at a first rotational position of the crankshaft and seals the chamber from the opening at other rotational positions of the crankshaft.

Abstract: A piston comprising a lower part with a bore having a concave surface against which abuts the convex surface of a head of an expansion socket, the center of curvature of the concave surface lying on the axis of the bore and the head being formed in two halves with each half having a center of curvature lying offset from the axis of the bore.

Abstract: An improved piston and rod assembly that can be readily disassembled at several places so that the entire assembly need not be necessarily removed from an engine during servicing, and which includes dismantleable bearings around a cross pin about which the piston is pivotally supported on the piston rod, and a dismantleable bearing that supports the piston rod on a crankshaft, and shims being placable behind the bearing blocks so to selectively change a length of piston stroke within a cylinder.

Abstract: An improved piston assembly comprising a generally cylindrical body having at one end a peripheral shoulder and at the other end a depending skirt, an annular ring groove protection band formed of hard metal and having a peripheral, radially outwardly opening ring receiving groove seated on the shoulder, and a crown secured to the body one end and having a radially outwardly extending flange engaging the band about its periphery and clamping the band against the shoulder. Insulating means are interposed between the crown and the band.

Abstract: An improved piston assembly including a generally cylindrical piston body having a crown and a depending skirt and being formed of a light-weight metal, an annular ring groove protection band formed of a hard metal disposed about the body adjacent the crown and having at least one peripheral groove adapted to receive a compression ring, and securing devices including a plurality of elongated threaded fasteners clampingly securing the band to the body, the threaded fasteners extending longitudinally of the body and having a length sufficient to store substantial clamping energy whereby the components of the assembly will not loosen during use of the assembly.

Abstract: A light weight piston assembly including a piston body formed of a light-weight metal and having a crown and a depending skirt, an annular recess about the end of the body adjacent the crown and opening toward the crown, the portion of the recess immediately adjacent the crown being threaded, a hard metal ring groove protection band having a peripheral, radially outwardly opening ring receiving groove disposed in the recess, at least one annular wavy spring in the recess, and a nut threaded on the threaded portion securing the band and the spring within the recess such that the spring is compressed to store energy to tightly hold the band against movement relative to the body during various piston operating conditions.

Abstract: A threaded cap screwed into the piston head with a sealed joint to a sleeve tube open and flanged at the other end are provided to encase the clamping screws that fasten the piston head and the upper piston body member and lower piston body member together. The casing thus formed shields the screws from possibly corrosive coolant that under operating conditions could work through the joints between the parts of a composite piston in spite of the clamping pressure of the screws. Each screw is screwed into the threaded cap at the piston head end and its head or a nut bears on the flange of the sleeve tube at the other end. The screws and their protective casings fit within bores in an annular strut forming a large part of the upper piston body member that butts against a low annular ridge on the underside of the piston head into which the end caps of the screw casings are screwed.

Abstract: In a piston-cylinder assembly with a shaftless piston, the aim is to improve the lateral guidance of the connecting rod, to reduce edge wear and the seizing tendency in the event of fault during the combustion process. Consequently, the piston has at least one supporting ring, form-fittingly on the bosses which guides in the cylinder the piston along with the piston head.