Abstract: A brake master cylinder comprising a housing having an inner surface defining a bore, and a piston movable in the bore along a piston axis. The piston includes two spaced apart lands defining the radially outermost surfaces capable of contacting the inner surface. At least one of the lands is longitudinally curved at the radially outermost surface. For example, the land can be curved at a radius of less than 1 inch (e.g., between 0.15 inch and 0/75 inch) and preferably less than 0.5 inch. In one embodiment, the longitudinally curved land includes two edges that define an axial length of the land. The two edges have a radius of less than 0.2 inch, and preferably about 0.1 inch. The relative position of the edges and lands is such that neither of the two edges is capable of contacting the inner surface of the bore during reciprocating movement of the piston in the bore.

Abstract: A piston may include a piston upper part and a piston lower part. The piston upper part may be welded via a contact surface with the piston lower part forming a cooling duct therebetween. The cooling duct may define an inlet opening and an outlet opening extending from the piston lower part in the cooling duct. A welding bead may be formed within the cooling duct at each of the inlet opening and the outlet opening.

Abstract: The invention relates to a piston (10, 110, 210) for an internal combustion engine, comprising a piston head (11, 111, 211) and a piston skirt, the piston head (11, 111, 211) having a circumferential ring section (15, 115, 215) and a circumferential cooling channel (16, 116, 216) in the region of the ring section (15, 115, 215). The cooling channel has a cooling channel floor (17, 117, 217) and a cooling channel ceiling (18, 118, 218). According to the invention, the cooling channel (16, 116, 216) has a narrowing (20, 120, 220).

Abstract: An exemplary piston assembly and method of making the same are disclosed. An exemplary piston assembly may include a piston crown and skirt. The crown may include radially inner and outer crown mating surfaces, and the crown may define at least in part a cooling gallery extending about a periphery of the crown. The skirt may further include an inner collar wall disposed radially inwardly of a radially inner interface region and extending upwards to a free end. The collar wall may generally enclose the radially inner interface region from the central region.

Abstract: A piston assembly and a method of making the same. Exemplary piston assemblies may include a piston crown having a ring belt portion defining a cooling gallery, and a strut extending away from the ring belt portion to define a wrist pin bore. The piston may further include a piston skirt assembly secured to the strut. The piston skirt assembly may include two separate portions that each have a closure plate formed integrally with the portion, with the closure plate generally enclosing the cooling gallery. Exemplary methods of assembling a piston may include providing a piston crown having a ring belt portion defining a cooling gallery and a strut extending away from the ring belt portion to define a wrist pin bore. The methods may further include forming a piston skirt assembly having two portions having a closure plate integrally formed therewith, and securing the skirt to the crown.

Abstract: A method for the production of a piston for an internal combustion engine, in which a piston blank is forged, which is subsequently separated into two parts, to form an upper piston part and a lower piston part, after which the lower piston part and the upper piston part are machined and then welded to one another. Subsequently, the piston is finished. During forging of the piston blank, the top of the piston blank is partly given the shape of the underside of the upper piston part, and the underside of the piston blank is given the shape that corresponds to the interior of the lower piston part. After forging of the piston blank and before separation of the upper piston part from the lower piston part, the top of the piston blank is given the finished shape of the underside of the upper piston part by a cutting machining method.

Abstract: A piston head is formed to have a bowl, micro chambers in the piston body adjacent to the bowl, and orifices providing communication between the micro chambers and the bowl. The micro chambers are formed in the piston head by using grooves that in part define the volume of the reaction chambers, and which are completely sealed from above with permanently secured plugs.

Abstract: A piston for an internal combustion engine has a lower piston part and an upper piston part that are connected with one another by friction welding and form an outer circumferential cooling channel. The upper piston part has a circumferential ring belt provided with ring grooves, the inner wall of which delimits the circumferential outer cooling channel. An outer circumferential friction-weld seam is provided below the ring belt, the width of which seam is less than or equal to the wall thickness between the groove root of the ring grooves and the inner wall of the ring belt.

Abstract: An exemplary piston may include a piston body having radially inner and outer body mating surfaces. The piston may further include a cooling gallery ring cooperating with the piston body to form a continuous upper combustion bowl surface and a cooling gallery. The cooling gallery ring may have radially inner and outer ring mating surfaces abutted along their corresponding radially inner and outer body mating surfaces, such that the cooling gallery is substantially enclosed. The piston body and cooling gallery ring may be joined together along the radially inner and radially outer interface regions to form a generally one-piece piston assembly. The radially outer interface region may be elongated in a direction parallel to the piston axis, e.g., facilitating a laser welding joining process.

Abstract: A method of friction welding a piston includes forming a piston body by friction welding an upper crown portion to a lower crown portion. At least one of the upper or lower crown portions is provided with a central support post extending along a central axis. The upper and lower crown portions have annular ribs radially outwardly from the central support post, with the ribs being aligned with one another. The method includes initiating a friction weld joint between a free end of the central support post and a corresponding surface opposite the free end of the central support post. Then, after initiating the weld joint between the central support post and the opposite surface, the method continues by then initiating a friction weld joint between aligned free ends of the ribs. Then, the friction weld joints are completed.

Abstract: A piston for a compression ignition internal combustion engine includes a crown portion, torroidal portion, and a reentrant portion. The piston further has a recess portion about a central axis of the piston designed to reduce temperatures near a tip portion of the fuel injector.

Abstract: The present invention relates to a multi-part piston (10) for an internal combustion engine, having an upper piston part (11) having a piston crown (13), and a lower piston part (12), whereby the lower piston part (12) has pin boss supports (32) and pin bosses (18) connected with them, whereby the upper piston part (11) and the lower piston part (12) each have an inner (21, 25) and an outer (22, 26) support element, which elements delimit an outer circumferential cooling channel (29). According to the invention, it is provided that the inner support elements (21, 25) delimit a cavity (31) that is open toward the pin bosses (18), and that the cavity (31) is provided with a separate cooling oil collector (35) that has at least one cooling oil opening (37, 38).

Abstract: Exemplary piston assemblies and methods of making the same are disclosed. An exemplary piston assembly may include a piston crown and a piston skirt that is received in a central opening of the crown. The piston crown may include a ring belt portion defining, at least in part, a cooling gallery. The crown and skirt may each further include corresponding mating surfaces that extend about a periphery of the crown and skirt. The skirt mating surface and crown mating surface may generally be secured to each other that the crown and the skirt cooperate to form a continuous upper combustion bowl surface. The skirt and crown may cooperate to define a radially outer gap about a periphery of the piston crown.

Abstract: A piston has an upper crown portion with an upper combustion wall against which combustion forces act and a lower crown portion with a pair of pin bosses spaced for receipt of a small end of a connecting rod therebetween. The upper crown portion and the lower crown portion form an outer oil gallery and a central oil gallery in fluid communication with one another. The central oil gallery is formed in part by an annular flange extending radially inwardly from the outer oil gallery and upwardly toward the upper combustion wall to a free edge spaced from the upper combustion wall. The free edge forms an opening about a central axis of the piston and has a non-planar uppermost surface with depressions aligned diametrically opposite one another across the opening to improve the oil flow throughout the central oil gallery.

Abstract: A piston, especially a cooling channel piston of an internal combustion engine, has an upper part and a lower part which can be produced separately from each other and subsequently be assembled. The upper part has at least three radially peripheral joining webs and the lower part likewise at least three radially peripheral joining webs. During assembly, the webs are put together and connect the upper part firmly to the lower part.

Abstract: An exemplary piston assembly and method of making the same are disclosed. A piston assembly may include a piston crown and piston skirt. The crown may include a ring belt portion defining at least in part a cooling gallery, as well as radially inner and outer crown mating surfaces. The skirt may be received in a central opening of the crown such that the crown and skirt cooperate to form an upper combustion bowl surface. The skirt also may include radially inner and outer skirt mating surfaces that are abutted with the inner and outer crown mating surfaces, respectively, such that the cooling gallery is generally enclosed by the skirt.

Abstract: A piston for an internal combustion engine is provided. The piston crown includes an interior surface that defines at least in part a cooling gallery and a cooling gallery surface within the piston. An annular surface may defines at least in part an annular passageway that allows fluid communication between an outer surface of the piston and the cooling gallery. Opposing annular surfaces may be abutted with a predetermined force, thereby limiting fluid flow from the cooling gallery to an outer surface of the piston. Further, an annular surface may extend into the cooling gallery to form a deflector along the cooling gallery surface, thereby limiting fluid flow from the cooling gallery to an outer surface of the piston.

Abstract: A piston and method of making a piston which involves providing a single piece piston blank that, after casting or forging, is separated into separate upper and lower portions. The upper portion is machined to develop a piston head having that includes a cooling gallery portion and the lower portion is machined to develop a piston body having a cooling gallery portion, a skirt and a pair of opposed pin bores. After machining the piston head and piston body are attached together and the resulting assembly is machine finished into a finished piston.

Abstract: A monobloc piston has at least two steel parts welded together to define an inner cooling gallery. An outer ring belt is spaced from an inner annular support wall and is joined by a combustion bowl and a lower wall. A pair of pin bosses have axially aligned pin bores. A skirt is formed as one immovable piece with the pin bores. The piston has the following dimensional relationships: ISMD=42-55% of BD, where ISMD is a mean diameter on the inner support wall and BD is an outer diameter of the ring belt wall, ISW=3-8% of BD, where ISW is a sectional width of the inner support wall, CH>53% of BD where CH is a compression height measured between the pin bore axis and the upper surface, TLH>4% of BD, where TLH is a top land height measured between the top of the upper ring groove and the upper surface, SL=30-80% of BD, where SL is a length of the skirt measured between the upper and lower ends of the skirt, SW=2.5-6.

Abstract: A multi-axially forged mono-bloc piston includes a lower crown part forged of steel and including a pair of pin bosses and an integral skirt formed as one piece with the pin bosses 20. The lower crown part is friction welded to an upper crown part to form at least one closed oil gallery within the piston head. The lower crown part is forged in the longitudinal direction of the piston as well as laterally to impart longitudinal and laterally forged features of the piston. The laterally forged features may comprise undercut recesses formed in the piston skirt to reduce material in the overall piston structure. The lateral forging may also result in the piston skirt portion being discoupled from the piston head by laterally forged slots formed in the lower crown part 14 between the skirt and head.

Abstract: A multipart cooled piston for a combustion engine has a piston upper part of steel comprising a combustion bowl and a ring wall with ring belt, and a piston lower part comprising a piston skirt, pin bosses for receiving the piston pin connecting the piston to the connecting rod, and pin boss supports connected to the piston skirt. An inexpensive manufacture and high form stability are achieved in that a cooling channel formed in the piston upper part has holes towards the piston crown spread over its circumference, with the piston material present between such holes forming supporting ribs that each form sections of an all-round ring rib radially to the longitudinal piston axis (K), The piston lower part has an annular and all-round carrier rib with a connection surface connected to the pin boss supports.

Abstract: A heavy duty diesel piston includes upper and lower portions joined across a friction weld and internally contoured to provide a dual gallery structure including an outer annular gallery and a central gallery joined by passages for communicating cooling oil therebetween. The dual-gallery structure allows oil to enter from the outer gallery, which is formed by the circumferential annular recess in the crown and crown bottom, into the central gallery to cool the piston and particularly the central crown region exposed to hot combustion gases. The friction weld provides high structural integrity and minimizes the number of manufacturing steps needed to attach the crown to the crown bottom.

Abstract: A piston (10) particularly suited for heavy duty diesel engine applications includes upper and lower crown sections (28, 30) joined by a friction weld (32) to define an annular ring belt (14) formed with ring groves (22) and having a lower end (20) and an internal piston cooling chamber (34). A pair of pin bosses (40) depend from the ring belt (14) and are formed as one piece with the lower crown section (30). A skirt (46) is also formed as one piece with the pin bosses (40) and has an upper end (48) that is spaced from the lower end (20) of the ring belt (14) to define a space (52) therebetween which effectively uncouples the skirt (46) from the ring belt (14).

Abstract: A monobloc piston has at least two steel parts welded together to define an inner cooling gallery. An outer ring belt is spaced from an inner annular support wall and is joined by a combustion bowl and a lower wall. A pair of pin bosses have axially aligned pin bores. A skirt is formed as one immovable piece with the pin bores.

Abstract: A steel monobloc piston for diesel engines is formed with a relatively short piston skirt whose lower edge resides below the axis of the pin bores of the piston, but located at or above a lowest tangent point of the pin bores. The piston body preferably has a closed oil cooling gallery and the skirt is preferably joined at its upper end to an outer wall of the piston in which a plurality of ring grooves are formed.

Abstract: A steel monobloc piston for diesel engines is formed with a relatively short piston skirt whose lower edge resides below the axis of the pin bores of the piston, but located at or above a lowest tangent point of the pin bores. The piston body preferably has a closed oil cooling gallery and the skirt is preferably joined at its upper end to an outer wall of the piston in which a plurality of ring grooves are formed.

Abstract: The piston for a magneto-rheological fluid system is manufactured from a piston skirt of a material having a high magnetic permeability and a piston plate which closes one end of the piston skirt having a low magnetic permeability and therefore must be made out of a material such as stainless steel. The piston is manufactured by placing the plate on one electrode and clamping another set of electrodes against the outer circumferential surface of the piston ring or skirt. The plate and ring are brought into contact with one another while applying a current through the piston ring and the piston plate, thereby heating interfering portions of the ring and plate and permitting the plate to be forced inside of the ring while at the same time allowing the softened or plastic portions of the ring and plate to intermingle with one another and thus form a solid state bond.

Abstract: A heavy duty diesel piston includes upper and lower portions joined across a friction weld and internally contoured to provide a dual gallery structure including an outer annular gallery and a central gallery joined by passages for communicating cooling oil therebetween. The dual-gallery structure allows oil to enter from the outer gallery, which is formed by the circumferential annular recess in the crown and crown bottom, into the central gallery to cool the piston and particularly the central crown region exposed to hot combustion gases. The friction weld provides high structural integrity and minimizes the number of manufacturing steps need to attach the crown to the crown bottom.

Abstract: A constructed piston 1 is comprised of an upper part 2 produced from forged steel, and a bottom part 3, said parts being joined with the expansion screws 4. The bottom part 3 consists of a forged part 6 produced from steel, with the bosses 7 and an approximately tubular shaft extension 5 consisting of an iron material, said extension being joined with the part 6 by welding. In the lower zone of the shaft extension 5, the latter has a collar 8 that can be worked for the purpose of adjusting a piston weight within the tolerance range.

Abstract: A method of manufacturing a piston for heavy-duty diesel engine applications comprises forming a piston body having a pair of pin bosses, and bonding separately formed skirt portions to the pin bosses. The resultant piston has the separately formed skirt portions united to the piston body in a monobloc piston construction.

Abstract: A one piece piston for an internal combustion engine has a piston skirt that is connected to a flange portion and a supporting portion of a piston body. The piston skirt provides support to the flange portion and a piston ring belt portion disposed about and connected to the piston body. The one piece piston has a closed piston cooling gallery defined by the piston body, the flange portion and piston ring belt portion.

Abstract: A piston (10) particularly suited for heavy duty diesel engine applications includes upper and lower crown sections (28, 30) joined by a friction weld (32) to define an annular ring belt (14) formed with ring groves (22) and having a lower end (20) and an internal piston cooling chamber (34). A pair of pin bosses (40) depend from the ring belt (14) and are formed as one piece with the lower crown section (30). A skirt (46) is also formed as one piece with the pin bosses (40) and has an upper end (48) that is spaced from the lower end (20) of the ring belt (14) to define a space (52) therebetween which effectively uncouples the skirt (46) from the ring belt (14).

Abstract: A one-piece piston comprises a piston crown made of steel and a bottom component made of forged steel, and a cooling channel that is formed by welding the crown and the bottom component of the piston together. The cooling channel is located radially behind the annular grooves. The crown and the bottom component of the piston jointly form a central cooling chamber whose lower limiting wall is forged as one piece with the bottom component of the piston. The welding seams joining the crown and the bottom component of the piston are friction welding seams. The piston provides for superior cooling of the crown of the piston and simplifies the production of the welding seams.

Abstract: Past pistons have been susceptible to reduced longevity due to increased forces of combustion thereon during operating cycles of an engine. The present two piece unitary piston increases the longevity of pistons used with increased forces of combustion. For example, a head member has a bottom surface and a support surface. And, a skirt member defines an upper outer support surface and an upper inner support surface. The head member and the skirt member have a preestablished material strength being generally the same. The head member and the skirt member are joined at an interface of the bottom surface and the upper outer support surface and the interface of the support surface and the upper inner support surface respectively by a welding process. The force of combustion acting on the crown portion is resisted by the upper outer support surface being in contacting relationship with the bottom surface.

Abstract: A one-piece piston (20) formed by an upper crown (28) and a lower crown (30) having an integral skirt (24, 26). The upper crown (28) includes an upper surface (32) and a lower surface (34, 42). The lower crown (30) includes an upper surface (50) and two pin bosses (52, 54). The upper crown (28) has a first collar (44) and the lower crown (30) has a second collar (64). In addition, skirt ribs (24, 26) connect the two pin bosses (52, 54). The first and second collars (44, 64) are secured together to form the one-piece piston (20).

Abstract: This invention relates to a high temperature-resistant piston head. The piston head includes a first portion formed of a first material of heat-resistant steel alloy and the second portion is formed of a second a material of steel alloy that may be the same or may or different from the first material. The first and second portions are joined by a friction weld to form the assembled piston head. The heat-resistant steel alloy includes about 0.1 to about 0.5 wt % carbon, up to about 0.6 wt % manganese, about 4.0 to about 6.0 wt % chromium, about 0.45 to about 0.65 wt % molybdenum, up to about 0.5 wt % nickel and the balance iron and incidental impurities. In one form the second material includes about 0.30 to about 0.55 wt % carbon, about 0.4 to about 1.10 wt % manganese, about 0.40 to about 1.25 wt % chromium, about 0.15 to about 0.45 wt % molybdenum, up to about 0.4 wt % silicon, up to about 2 wt % Ni and greater than about 90 wt % iron.

Abstract: Past pistons have been susceptible to reduced longevity due to increased forces of combustion thereon during operating cycles of an engine. The present two piece unitary piston increases the longevity of pistons used with increased forces of combustion. For example, a head member has a crown portion defining a ring band portion having a bottom surface and a support portion. And, a skirt member defines a ring band support surface and a top surface. The head member and the skirt member have a preestablished material strength being generally the same. The head member and the skirt member are joined by an inertia welding process. The force of combustion acting on the crown portion is resisted by the ring band support surface being in contacting relationship with the bottom surface. Thus, the skirt member structure supports and resists the bending moment of the combustion forces on the head member.

Abstract: Past pistons have been susceptible to reduced longevity due to increased forces of combustion thereon during operating cycles of an engine. The present two piece unitary piston increases the longevity of pistons used with increased forces of combustion. For example, a head member has a crown portion defining a ring band portion having a bottom surface and a support portion. And, a skirt member defines a ring band support surface and a mating portion. The head member and the skirt member have a preestablished material strength being generally the same. The head member and the skirt member are joined at an interface of the support portion and the mating portion by an interference fit and are joined at the interface of the bottom surface and the ring band support surface by a weld. The force of combustion acting on the crown portion is resisted by the ring band support surface being in contacting relationship with the bottom surface.

Abstract: A piston head is provided which is lightweight and inexpensive yet capable of handling high mechanical and thermal loading during operation. The piston head generally includes a top head portion and a bottom head portion formed separately and connected by a friction weld. Importantly, the top head portion includes a first cooling gallery formed between the depending outer wall and a first inner depending wall and a second cooling gallery formed between the first inner depending wall and a second inner depending wall. The bottom head portion also includes corresponding first and second upper extending walls connected to the first and second inner depending walls to form the lower portion of each cooling gallery. The inner depending and upper extending walls are formed so that the ratio of the sum of the transverse thickness of the adjacent walls to the outer diameter of the piston head is approximately from 2% to 8%, and preferably 4% to 6%.

Abstract: The piston made in accordance with the teachings herein includes a primary compression ring groove, a bottom and rear wall surface of which are hardened by the method of laser hardening. The method includes the steps of spraying the primary groove with a graphite spray and then directing an angled elliptical in cross section laser beam at the bottom surface of the groove while rotating the cylinder head at predetermined parameters.

Abstract: An annular composite insert is cast which includes distinct particles such as cast iron dispersed throughout the base metallic alloy. The insert is then placed in a piston mold, and a piston cast such that the insert maintains a radially outer face generally flush with a radially outer surface of a piston head of the piston. The base metal of the poured piston is preferably the same as that of the insert so that the insert bonds to the piston head and shares the same thermal expansion characteristics. The insert is machined to form grooves adapted to receive a piston ring. The particles of the insert are exposed to provide superior wear resistance, support to the piston ring so that microwelding is reduced, and also to act as a dry lubricant in a preferred embodiment.

Abstract: The assembly is used in a reciprocating hermetic compressor of the type comprising a cylinder block (4), presenting a cylinder (11), within which a piston (20) reciprocates, a smaller eye (31) of a connecting rod (30) being introduced into and retained inside said piston (20), through an articulating pin (40), having its end portions supported on respective radial lateral openings of the piston, wherein the portions, which are defined by the peripheral edge of at least one end of the articulating pin and the adjacent internal surface (23a, 24a) of the respective lateral radial opening (23, 24) of the piston (20), are attached to each other by at least one welding spot contained in a respective first welding region, located in a sector of about 90 degrees of said end and symmetric to a diametral line of said end of the articulating pin (40), said line being parallel and coplanar relative the longitudinal axis of the piston (20), at least one welding spot being provided in at least a second welding region oppos

Abstract: A cooled piston head and method of manufacture, the piston head having a closed cooling chamber. In one embodiment, the piston head is formed of a top member, an intermediate member and a pin boss member joined to each other preferably by welding; the top and intermediate members are provided with circumferential grooves which defines the closed cooling chamber. In an alternate embodiment, the head is formed of a top member and a pin boss member joined together preferably by welding; the closed cooling chamber is defined by circumferential grooves provided on both members.

Abstract: Pistons and a method for their manufacture are described. The piston has at least one piston ring groove reinforcing member being annular in form and having, in cross-section, upper and lower, generally radially extending face portions and a radially inner, generally axially extending face portion between the two generally radially extending face portions, the generally axially extending face portion being coated with particulate material by a physical vapor deposition technique, to provide a porous adhesion assisting layer.

Abstract: A method for the manufacture of a piston head having a cooling chamber is disclosed. The two portions composing the piston head are made separately; the underside of the upper portion is provided with a circumferential peripheral groove; notches are provided on both sides of the open end of the circumferential peripheral groove; a circumferential annular plate is placed on the notches thereby closing the circumferential peripheral groove; the two portions making up the head are joined to each other by welding and cause the inner edge of the annular plate to be retained in the piston head and become an integral part thereof.

Abstract: A ceramic-metal friction welded member includes a ceramic member formed with an annular notch in an outer circumference of its surface and a metal member joined onto the annular notch of the ceramic member by friction welding. A ceramic cast-in bonded piston includes a crown made of a ceramic material having an annular notch formed in an outer circumference of its surface, a metal annular member joined onto the annular notch of the crown by friction welding, and a piston main body made of an aluminum alloy surrounding the crown by cast-in bonding. A ceramic cast-in bonded piston includes a crown made of a ceramic material, a piston main body made of an aluminum alloy surrounding the crown by cast-in bonding, and an annular member made of a metal different from aluminum and joined by friction welding to an outer circumference of a surface of the crown in contact with the piston main body.

Abstract: Pistons and a method for making them are described. The pistons have reinforcing components, such as piston ring groove inserts, incorporated therein. The reinforcements have one or more porous bodies joined thereto, for example, by brazing and which are infiltrated during casting of the piston.

Abstract: A method for the manufacture of a two-piece piston wherein the top portion and the pin boss portion, which define the piston head, are fabricated separately by cold or hot forming, casting or sintering, and joined together by welding such as, for instance, friction welding. The top portion and the pin boss portion may be of the same material or different materials, and obtained by the same method or by different methods.

Abstract: An aluminum torpedo piston is provided with a piston head fabricated from a etal matrix composite material composed of aluminum and silicon carbide fibers that are integrally joined by an inertial welding technique. A 23% weight of silicon carbide fibers to powdered aluminum was selected. Resistance to intense heating which would otherwise cause melting and erosion of the piston is avoided to permit longer, high speed runs.

Abstract: The detonation-resistant material is applied to a piston to reduce the likelihood of damage to the piston caused by pinking or knocking. The detonation-resistant material, which may be nickel or a nickel based material, is applied to the upper part of the ring band and around an annular portion of the crown adjacent the edge of the crown. The ring band is, before treatment, machined to form a recess extending therearound which is filled with the detonation-resistant material by a plating process. Thus, on the ring band, the detonation-resistant material does not extend radially outwardly of the remainder of the ring band. This reduces the possibility of the detonation-resistant material scraping or scuffing on the associated cylinder or liner during movement of the piston in the associated cylinder or liner and also reduces the likelihood of the detonation-resistant material being scraped off.