Abstract: A carrier vehicle having a swing table supported on an under-carriage so as to swing a full turn, and a planetary reduction gear for reducing the revolution of a drive motor and transmitting it to the swing table. The planetary reduction gear is mounted on the under-carriage under the swing table.

Abstract: A number of embodiments of direct piston pin lubrication systems for reciprocating machines such as internal combustion engines. In all of the embodiments, the hollow interior of the piston pin is employed as a distribution passage with radial drillings extending through the piston pin for lubricating the various journals thereof. In some embodiments, the lubricant is sprayed through the wall of the cylinder bore directly into the piston pin and in others it is delivered through a passage formed in the piston.

Abstract: In a piston/liner arrangement for a reciprocating-piston internal combustion engine, wherein a piston with a skirt is axially movable in the liner, at least one of the piston skirt and the liner includes sections with an open-pore surface structure in which a lubricant with a high affinity to the material having the open-pore surfaces structure is disposed so as to form a lifetime lubrication arrangement.

Abstract: An axial plunger pump includes an auxiliary plate mounted to a cam plate at an end thereof on the side of a cylinder block to be rotatabe relative to the cam plate, and a flexible partition member interposed between a housing and the auxiliary plate to cover a drive shaft and the cam plate. The flexible partition member, which is in the form of, e.g. a metal bellows, serves to divide the inside of the housing into a working fluid chamber and a lubricant chamber.

Abstract: A piston-type compressor is provided with a lubricating system for allowing passage of blowby gas from a piston chamber to a crank chamber, which is disposed opposite the piston from the piston chamber. A driving mechanism is disposed in the crank chamber and is coupled to the pistons to move the pistons in a reciprocating motion. The lubricating system may comprise at least one groove formed in an inner surface of at least one of the cylinders to allow passage of a fluid and a lubricating oil, via blowby gas, from the piston chamber to the crank chamber. The fluid may lubricate the moving parts of the driving mechanism.

Abstract: A plurality of passageways were provided between the inter-ring cylindrical surface of a piston and a cavity formed behind an oil control ring mounted on the piston. The passageway provides for the passage of blowby gas during downward movement of the piston, thereby permitting the oil control ring to seat against the upper surface of its groove. The present invention effectively controls the flow of oil toward the compression ring of the ring assembly without the requirement for a passageway communicating the inter-ring cavity with a saturated, turbulent flow, oil environment.

Abstract: A hydraulic piston engine driven by a lubricant-free, water-based pressure fluid, and comprising an enclosing housing and a piston-connected drive shaft supported by radial journal bearings in bearing bushings. One of the sliding surfaces of the radial journal bearing comprises a recess with a bearing-supporting hydrostatic pressure fluid pocket. The center of the recess is displaced by an angle (.alpha.) in the direction against the direction of rotation of the drive shaft, seen in relation to the geometrical, radial mean point in the high-load area for transmission of the piston forces to the bearing surface via the drive shaft. Hereby a particularly reliable piston motor of the type indicated is provided.

Abstract: A dough divider is provided having a piston and cylinder mechanism for repeatedly pressing dough into a measuring cup assembly. Dough is drawn from a hopper into the cylinder through a tube. A lubrication port is disposed in the tube, and a channel extends from the port to the cylinder. The port and channel arrangement provide a self-cleaning lubricating arrangement which keeps the dough from sticking.

Abstract: A fluid pump for displacing a small, precise volume of fluid for each pump stroke, particularly where the fluid to be displaced is a liquid containing dissolved gas. The precise volume of fluid to be displaced is adjustable to any selected amount up to the full displacement of the pump. The pump has instrumentation that indicates a seal failure within the pump, thus allowing for maintenance on the pump before a total failure. This instrumentation results in increased safety when the pump is used to inject odorant into a natural gas pipeline or in other precision chemical injection applications.

Abstract: A hydraulic cylinder bearing gland for seals hydraulic cylinder chamber having an a piston rod extending externally therefrom and includes a cylindrical sleeve with an inner bearing surface having an axial length greater than the outer diameter of the piston rod. The inner bearing surface also has a spiral, helical groove machined therein permitting fluid flow from the cylinder chamber along the length of the inner bearing surface of the bearing gland. A primary seal allows low volume flow of hydraulic fluid therethrough to prevent outside contamination from entering the cylinder chamber, while a secondary seal preventing fluid from exiting the cylinder. A port and annular groove between the primary and secondary seals return the flow of hydraulic fluid to a reservoir.

Abstract: An axial multi-piston compressor having a drive shaft which rotates and a cylinder block having a multiplicity of cylinder bores and pistons within the cylinder bores. The cylinder block is associated with a crank chamber containing the fluid to be compressed and a lubricating oil mist. The peripheral wall of the crank chamber having a groove on the peripheral surface which groove collects oil and directs the oil to the shaft seal. The groove is partially curved in a direction counter to the direction of rotation of the shaft.

Abstract: A reciprocating vacuum pump has a disc shaped piston (22, 122) having a peripheral elastomeric seal (52, 152) with oppositely directed, radially outwardly extending skirt portions (54,56); the piston is driven axially by a rod (34, 134) reciprocal in a lubricated bearing (42, 142) and a lubrication flowpath (50,48; 150,148) is defined between the bearing (42, 142) and the side of the piston (22, 122) opposite thereto.

Abstract: An improved lubrication arrangement for a piston member arranged to be reciprocatingly movable in a cylinder element of an injection pump for fuel or the like pressure medium, wherein lubricant is supplied under pressure into a lubrication groove arranged in the cylinder element and encircling the piston member. The flow-through of the lubricant is improved by providing the cylinder element with at least one channel extending in the longitudinal direction of the cylinder element, which channel is connected with the lubrication groove for leading lubricant continuously into another position on the mantle surface of the piston member at a distance from the lubrication groove further to be recovered and for possible recirculation.

Abstract: A fuel injection pump for injecting compressed fuel to an engine through a reciprocative motion of a plunger includes a vertically-elongated plunger barrel, and a plunger having a shaft portion which is vertically and reciprocatively slidable along the inner space of the plunger barrel, at least one of the inner wall of the plunger barrel and the peripheral surface of the shaft portion of the plunger being formed with an oil groove for temporarily storing oil which ascends from a cam chamber through a reciprocative motion of the plunger, wherein the oil groove has at least two side walls one at the upper side of the oil groove and one at the lower side of the oil groove, and wherein lower side wall is downwardly slanted to return the stored oil to the cam chamber.

Abstract: A driving mechanism usable in an electron beam exposure apparatus, X-ray exposure apparatus, ion beam exposure apparatus, evaporation apparatus, chemical vapor deposition apparatus or otherwise, for rectilinearly moving a wafer carrying stage in a vacuum chamber is disclosed. The mechanism includes a guide shaft, a partition flange fixed to the guide shaft, a pair of bearing assemblies slidably mounted to the guide shaft and disposed on the opposite sides of the flange, a coupling barrel for coupling the paired bearing assemblies and covering the guide shaft portion between the bearing assemblies, and a fluid supplying system for supplying fluids to the opposite sides of the partition flange. With this structure, the stage can be moved rectilinearly by controlling the fluid pressures on the opposite sides of the flange, while retaining high vacuum in the vacuum chamber.

Abstract: A wobble plate type refrigerant compressor having a lubricating mechanism provided at a ball-and-socket joint between a wobble plate and a piston rod is disclosed. A wobble plate type refrigerant compressor includes a compressor housing having a cylinder block. A plurality of cylinders are formed around the periphery of the cylinder block and a piston is slidably fitted within each of the cylinders and is reciprocated by a drive mechanism. A crankcase is formed between the cylinder block and a front end plate of the compressor housing. The drive mechanism includes a drive shaft, a rotor fixed to the drive shaft and a wobble plate disposed on an inclined surface of the rotor. The piston rod connects the wobble plate to the piston. A ball at one end of the rod is received in a socket formed at the wobble plate to form a ball-and-socket joint. A hole is formed at the wobble plate to link one end surface of the wobble plate to the friction surface of the ball-and-socket joint.

Abstract: A high-performance, robust gas-compression device of long-term reliability is adapted in particular for storing nitrogen gas under compression, and includes a substantially cylindrical body (1), a piston (4) partially projecting into the gas-storage chamber (2), upper (7) and lower (6) piston guiding sleeves surrounding the piston, a lubrication chamber (9) formed in one of the guiding sleeves, adapted for holding a lubrication fluid for lubricating the guiding sleeves, and respective annular sealing joints (14, 19) which are accomodated in the guiding sleeves. One annular sealing joint is formed with an annular groove in communication with the principal gas-storage chamber, thereby exposing that sealing joint to a pressure prevailing in the principal gas-storage chamber; the other sealing joint is exposed to a constant pressure from the lubricating fluid.

Abstract: A powder-lubricated piston is disclosed for diesel engines, particularly adiabatic diesel engines and coal-water slurry fueled diesel engines. Rings are provided for the piston which flex in response to combustion within the combustion chamber.

Abstract: A fluid cylinder has improved wear rings in a combination that includes a tube having a tubular wall and first and second end caps. The tubular wall defines a cylinder bore that has a central axis. Each end cap also has a bore extending along the central axis. A piston assembly is mounted in the cylinder bore with a piston rod mounted in the bore of one of the end caps, so that the piston assembly is slidable along the central axis. The piston assembly includes a piston head that has a reservoir defined by an annular recess opening toward the tubular wall. The reservoir houses a prepacked lubricant. One wear ring closes off the annular recess from the tubular wall. The wear ring seal has a plurality of radial apertures extending therethrough, through which lubricant is capable of flowing to lubricate the piston assembly. Another wear ring closes off a reservoir in the bore of an end cap and functions as the first mentioned wear ring also to lubricate the piston assembly.

Abstract: A through hole in a cylinder block through which a bolt is inserted to assemble the cylinder block and the front and rear housings as one body, and is positioned above a horizontal plane on which a drive shaft lies, is utilized as a part of a passage for a lubricating oil so that a sufficient lubrication is supplied to a thrust bearing and other elements, and thus an effective mass production of a swash type compressor can be carried out because it becomes unnecessary to form an oil passage in the drive shaft, which passage is difficult to machine.

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: A lubrication mechanism for an engine cylinder includes upper and lower ring troughs on the inside wall of the engine cylinder. The two ring troughs can accommodate oil pipes and ring oil nets. The oil pipes include an inlet pipe and an outlet pipe. Channels and numerous oil pores are defined by the pipes to allow the entrance of lubricating oil into the oil pipes, and seepage from the pores on the oil pipe, through a ring oil net to provide lubrication to the inside wall of the cylinder. The lubricating oil then flows downwardly to the lower ring oil net, through the net and the oil pipe, and into an outlet pipe for discharge.

Abstract: In order to increase the delivery pressure of the reciprocating pump-actuating mechanism of hydraulic feed pumps having a high pumping capacity, stacks of thin spacer discs are provided on either side of a sealing ring sealingly engaged in a sealing position between the plunger and the cylindrical bushing, said stacks of spacer discs being axially movable along the plunger in the normal non-sealing position. A pressure-distributing bushing is disposed between the stack of spacer discs which faces the free end face of the plunger and the sealing ring, said pressure-distributing bushing rapidly compensating the pressure between said stack of spacer discs and the end face of the pressure-distributing bushing facing the sealing ring.

Abstract: The very high pressure piston pump can compress a conveying agent (20) to a pressure of approximately 22 kbar. The high pressure sealing comprises a pressure-compensated ice sealing, which operates free of leakage and with reduced friction. To reduce the generally very high frictional forces in the ice sealings, a rotation is superimposed on the translation of the piston (10). The entire machine may be regulated by means of a microprocessor, depending upon the operational parameters and the feed efficiency. Its very high pressure seal has a long service life, even under continued operation in very high pressure ranges.

Abstract: The cylinders of the compressor each have a guide piston connected with a work piston with each being reciprocally mounted within a guide cylinder and work cylinder. In addition, seals are provided between the guide piston and the guide cylinder within a half-portion of the guide piston proximate to the work piston while a scraper ring is provided in a second half-portion of the guide piston remote from the work piston in order to meter lubricant between the guide piston and guide cylinder. Excess lubricant which is splashed from the crank case into the guide cylinder is returned via the scraper ring to the crank case.

Abstract: A hydraulic power drive unit for connection to the hydraulic system of an agricultural tractor is provided with a pressure release valve to protect the unit seal from damage if connected the wrong way round, and a bleed pipe which bursts to relieve pressure if the pressure release valve fails to operate.

Abstract: The presence of a lubricant in compressed gas from a reciprocating compressor including at least one cylinder 76 reciprocally receiving a piston 74 mounted on a rod 60 and connected to a rotary shaft 12 by a rotary to reciprocating motion converting mechanism 44 is avoided by placing a bellows 130 between the cylinder 76 and various components, including a piston rod guide 64, requiring lubrication.

Abstract: A housing of a reciprocating gas compressor comprises a partition member separating an upper suction chamber through which gas passes and a lower crankcase chamber in which a crankshaft rotates and which has an oil sump at the bottom. The partition member is imperforate except for sealed openings through which cylinder sleeves and hydraulic fluid lines extend between the chambers. A conduit located on the housing exterior and connected between the chambers performs three functions, namely: enables gas flow in either direction to effect pressure equalization; enables oil to flow by gravity from low points in the upper chamber into the sump; and enables oil mist in the gas flow through the conduit to coalesce on the inner walls of the conduit and flow by gravity into the sump.

Abstract: A bearing arrangement particularly useful for supporting the driveshaft of a thermal engine in which the driveshaft is acted upon by a rotating bending load. Since a rotating bending load of such thermal engines generates driveshaft bending deflections which rotate with the driveshaft, the bearings supporting the driveshaft must be capable of accommodating such deflection. Conventional rolling element type bearings can accommodate driveshaft deflection or wobble but have limited operational lifespans. In accordance with this invention, a driveshaft bearing arrangement is provided utilizing plane bearings having spherical surfaces which restrain radial loads while accommodating driveshaft wobble. In one embodiment, the spherical bearing includes a ring member affixed to the driveshaft having a spherical outer surface which closely conforms to a concave bearing surface.

Abstract: A method of packing elongated porous bodies moved between zones of different pressure, wherein the porous body (T) reciprocates through a pressurized packing agent (M). The packing agent is thixotropic and is supplied continuously to the porous cable (T) under a pressure exceeding the pressure in a higher pressure zone (P.sub.1) while the porous body (T) is impregnated with a thixotropic packing agent (M) such that the cross-section of the cable, throughout its entire length, is filled with packing agent (M). A hydraulic cylinder-type actuator utilizes a porous cable power transmission element packed in a chamber (7) filled with viscoelastoplastic material and communicated with means designed to develop in said chamber a pressure exceeding the pressure of the actuator working fluid.

Abstract: A carrier bracket for use with a power cylinder of the type having an elongated cylinder member and a reciprocally movable piston therein for transferring reciprocal movement of the piston to a desired workpiece. The carrer bracket includes a central bracket portion, a pair of guide arms extending outwardly from the central bracket portion in which each of the guide arms is provided with elongated surface, a mechanism to permit limited flexing movement of the arms relative to the central bracket so as to facilitate the limited selective movement of the arms toward and away from one another and a device for causing the limited selective movement of the arms toward and away from one another.

Abstract: An apparatus for providing a gas phase film lubrication between a reciprocal piston and a cylinder of an uncooled oilless internal combustion engine; the piston is effective to drive a rotary crankshaft in response to an expanding gas charge. The apparatus comprises: (a) means connecting the crankshaft to said piston for transferring reciprocal thrust into rotary thrust, such means aligning the piston concentrically within the cylinder wall to limit the imposition of side loads on said piston (i.e., less than 80 psi); (b) interfacing walls on the piston and cylinder (i) sized to provide a predetermined annular gap therebetween at ambient conditions that has a radial dimension in the range of 0.001.+-.0.

Abstract: This invention relates to a piston rod seal in which the rod along which leakage should be avoided is surrounded by a gland of a plastically deformable material. The gland is mounted at the high pressure side of a wall through which the piston rod is passed and is provided with a conical extension divering towards the high pressure side of the seal and acting as a pump for returning oil applied to the piston rod at the low pressure side of the piston rod and drawn through the gland. The gland is provided with a radial flange axially clamped between a metal ring and a spring support. An O-ring is mounted between the wall, the ring, and the gland.

Abstract: An actuator has a first connection point and a second connection point at opposite ends and is contractable along an axis extending between the connection points. The actuator has at least one hollow enclosure with an opening for admitting a pressurized fluid. A simultaneously radially expandable, axially contractable constraining means cooperates with the enclosure. The constraining means converts radial expansion of the actuator into axial contraction when pressurized fluid is admitted into the enclosure. In a preferred form, the constraining means comprises a network of non-stretchable, flexible tension links.

Abstract: A Stirling cycle engine is provided with gas cavities at an interface between an engine piston and a mating surface that guides the piston in its reciprocative motion to thereby achieve improved lubrication with the resulting gas film.

Abstract: The invention provides a piston and cylinder unit whose piston rod is sealed by a supporting and sealing arrangement arranged in an end cap of the unit. This supporting and sealing arrangement comprises a sealing portion made integrally with a stripper portion and joined therewith to form a sleeve-like sealing member surrounding the piston rod having the said portions at its ends. A lubricant-permeable supporting bushing encompassing the piston rod is mounted in the sealing member between the sealing and stripper portions and receives lubricant from lubricant reservoirs in the part of the sealing member between the stripper and sealing portions.

Abstract: A chuck actuator has a cylinder extending along an axis and having an axially extending stem whose outer surface is formed with a pair of central radially outwardly open and axially spaced intake ports, a piston axially displaceable in the cylinder and forming therein two compartments connected via respective passages connected to the intake ports, two axially spaced bearings on the stem, and a connector supported by the bearings on the stem. This connector normally is restrained against rotation relative to the axis and has an inner surface closely juxtaposed with and forming with the stem surface an interface. Respective radially inwardly open and axially spaced inner feed grooves open at the interface level with the respective intake ports. Two independent hydraulic fittings communicating with the inner feed grooves can pass pressurized liquid to the respective compartments.

Abstract: An actuator has a first connection point and a second connection point at opposite ends and is contractable along an axis extending between the connection points. The actuator has at least one hollow enclosure with an opening for admitting a pressurized fluid. A simultaneously radially expandable, axially contractable constraining means cooperates with the enclosure. The constraining means converts radial expansion of the actuator into axial contraction when pressurized fluid is admitted into the enclosure. In a preferred form, the constraining means comprises a network of non-stretchable, flexible tension links.

Abstract: A carrier bracket for use with a power cylinder of the type having an elongated cylinder member and a reciprocally movable piston therein for transferring reciprocal movement of the piston to a desired work piece. The carrier bracket includes a central bracket portion, a pair of guide arms extending outwardly from the central bracket portion, an elongated bearing rod secured in a fixed position relative to each of the inner surfaces of the guide arms, a mechanism to permit limited flexing movement of the arms relative to the central bracket so as to facilitate the limited selective movement of the arms toward and away from one another and a device for causing the limited selected movement of the arms toward and away from one another.

Abstract: A deformable sealing member, particularly a sealing tube, which is at least partially elastic is secured at two distant locations to two working members, e.g. to a piston part and a cylinder part, respectively, to form a leakproof working chamber for pressurizing therein a working fluid or for transferring the power of a pressurized working fluid introduced in the working chamber to said working members, the apparatus thus being able to operate as a pump or motor, respectively. The sealing member is supported against the working pressure in said chamber by a support surface, and between said sealing member and said support surface there is a low-friction component which is constituted by a solid material, e.g.

Abstract: A swash plate type compressor is provided with a compressor shoe having a sliding contact surface for making sliding contact with a swash plate. The sliding contact surface is formed with a central hole. A crest portion is formed between the hole and the outer periphery of the shoe, and smooth surface portions connect the crest portion with the hole and the outer periphery, the crest portion being located substantially at or inwardly of a radially middle point of the sliding contact surface between the hole and the outer periphery.

Abstract: In the case of piston-machines and in particular those having an elastically deformable sealing tube between the piston and the cylinder, which causes a relatively large structural length of the cylinder-piston arrangement and is provided if necessary with a forced feed for the lubricant, a reduction in the space requirement, in particular the structural length of the cylinder-piston arrangement is achieved by a driving member (30) associated with each piston (20) and embracing the associated cylinder (25) externally and extending over at least part of the length of the cylinder, and frictionally connected, e.g., to a rotating driving mechanism (10). The pulsating secondary space (35) formed by the driving member (30) at the outside of the cylinder (25) is connected for the avoidance of shock pressures because of filling with lubricant liquid flowing away, through a balancing channel (40) of large cross-sectional area to a pressure-balancing chamber (110).

Abstract: A swash plate type compressor having shoes provided with center holes on the slidable surfaces. The center hole provided with a bottom acts as a reservoir for lubricating oil and supplys the oil on the slidable surface of the shoe, which slides against the swash plate. There can be a second ring groove concentric to the center hole, or annexed grooves which are stretching outward radially from the center hole. The center hole also prevents the center part from protruding outward by thermal expansion, which is caused by friction. The slidable surface of the shoe is preferably coated with a layer containing solid lubricant so as to smooth the sliding motions.

Abstract: A gas pressure actuator for effecting the reciprocation of the stem of a valve subject to high-pressure loading comprises a tubular housing secured to the valve bonnet and defining a main cylinder chamber connected in axially series relationship with an auxiliary piston chamber which, in turn, communicates with a secondary fluid pressure chamber containing a compressible spring. A rod-like actuator is slidably and sealably mounted within the actuator housing and carries a main piston which cooperates with the main cylinder chamber in sliding and sealable relationship. The auxiliary piston chamber slidably and sealably mounts an auxiliary piston which is movable independently of the main piston. The actuating movement of the main piston produced by the introduction of gas pressure into the main cylinder produces an axial movement of the actuating rod and a compression of the spring. The spring-containing secondary chamber defined by the actuator housing is filled with a virtually non-compressible fluid.

Abstract: A piston pump arrangement is provided which includes a drivable crank shaft supported in a crank drive housing for rotational movement. The crank shaft is drivingly connected to horizontally disposed axially reciprocating pump pistons. In order to facilitate driving of the crank shaft from either the right side or the left side to accommodate the available space requirements and driving motor connections, the crank drive housing is provided with fastening support surfaces arranged symmetrically with respect to a plane through the axis of the crank shaft and the axes of the pump pistons. To accommodate attachment of auxiliary aggregates, such as lubricating/cooling circuit mechanisms, fastening points for such aggregates are also arranged symmetrically with respect to the plane of the crank shaft axis and the pump pistons.

Abstract: An improved lubrication system for lubricating the moving parts of a walking beam compressor used in compressing low pressure natural gas. The compressor is mounted on a walking beam oil pump. The lubrication system introduces oil through the length of a piston shaft and through a plurality of oil cooling chambers in the interior of a piston. The oil is then forced out through piston outlet ports disposed between the piston's compression rings and wear rings for providing an improved lubricant seal and extending the life of rings.

Abstract: The piston pin for a piston of an internal combustion engine is provided with a certain number of passages, each opening into the annular groove of the bearing bushing of the connecting-rod small end and into either of the annular grooves of the pin bearings. The passages are provided in a peripheral portion of the piston pin so to avoid a central portion of the pin, in which a concentration of metallic impurities is maximum.

Abstract: An improved lubrication system for the hydrostatic lubrication of an upper bearing and cylinder wall and piston of a walking beam compressor. The lubrication system introduces oil under pressure, around an upper bearing used for supporting a piston shaft connected to the piston of the walking beam compressor. The system having a pressure relief valve for relieving the pressure in the bearing and discharging excess oil into the top of the compressor and lubricating the cylinder wall and the sides of the piston.

Abstract: The device of the invention comprises a ball and socket and shoe assembly ich is pressure balanced with hydraulic fluid. This combination provides for low friction and relatively large travels when used as a linear to rotary motion actuator. In accordance with the contributions of the structural elements of the device, hydraulic pressure is applied to the rear of a piston by modulating the fluid pressure through a servo valve. Four pistons are typically used with two pistons driving the support spider clockwise and the other two driving the support spider counter clockwise. The control pressure produces a force through both the piston and pressure balanced shoes. The force is transmitted to the spider which is pivoted about flexures to produce a torque which results in a rotary motion of the spider (support).

Abstract: An apparatus for providing a gas phase film lubrication between a reciprocal piston and a cylinder of an uncooled oilless internal combustion engine; the piston is effective to drive a rotary crankshaft in response to an expanding gas charge. The apparatus comprises: (a) means connecting the crankshaft to said piston for transferring reciprocal thrust into rotary thrust, such means aligning the piston concentrically within the cylinder wall to limit the imposition of side loads on said piston (i.e., less than 80 psi); (b) interfacing walls on the piston and cylinder (i) sized to provide a predetermined annular gap therebetween at ambient conditions that has a radial dimension in the range of 0.001.+-.0.