Abstract: An improved rotational displacement apparatus is provided for measuring accurately the twist induced in an extension-twist coupled specimen in response to application of an axial load. The apparatus has an internal cylinder within which a piston rides. A piston rod extends from the piston through a pair of radial ball bearings in the base of the cylinder block to a free end outside the cylinder block. The piston is sized to be slightly smaller in diameter than the cylinder to provide a small space between the piston and the cylinder walls. A part for supplying compressed air to the region of the cylinder below the piston and a part for venting air from the region of the cylinder above the piston are provided. An optical encoder is coupled to measure rotational motion of the piston within the cylinder. In use, the apparatus is mounted in a testing machine and a specimen to be tested is secured at one end to the free end of the piston rod and at its other end to the mounting block of the testing machine.

Abstract: An oil return loop of a hydraulic cylinder which includes a plurality of equiangularly spaced V-shaped oil return grooves at the inside wall of an inner cylinder of the hydraulic cylinder for guiding saturated hydraulic oil to the outer cylinder of the hydraulic cylinder when the piston rod of the hydraulic cylinder is extended out. Each of V-shaped oil return grooves has two smoothly arched chamfered edges respectively disposed at connecting areas between the V-shaped oil return grooves and the inside wall of the inner cylinder to facilitate movement of the oil seal ring of the piston of the piston rod over the oil return loop.

Abstract: A reciprocating piston/barrel assembly, through which a fluid is capable of flowing, includes a piston having a pressure face separated from a downstream face by a side surface. A barrel has an interior wall surface defining a bore that is sized to slidably receive the piston. The bore is longer than the piston such that the bore includes an upstream volume adjacent the pressure face of the piston and a downstream volume adjacent the downstream face of the piston. The assembly includes some way for producing a pressure differential between the upstream volume and the downstream volume. The side surface and/or interior wall surface include at least one surface irregularity--indentation and/or protrusion--of sufficient size to increase flow resistance. In order to produce the axial force effect of the present invention, the fluid flow between the piston side surface and the barrel's interior wall surface must be faster than the speed of the piston.

Abstract: In a sealing device, a crank-shaped oil channel is defined in an abutment of a sealing ring for sealing between a shaft member and a housing which surrounds the shaft member and is rotatable relative the shaft member. The crank-shaped oil channel is comprised of a first oil channel portion and a second oil channel portion which extend axially, and a third oil channel portion which connects the first and second oil channel portions to each other. If the sealing ring is thermally expanded circumferentially due to a change in temperature, the sectional area of the flow path in each of the first and second oil channel portions is varied, but the sectional area of the flow path in the third oil channel portion is not substantially varied. Therefore, it is possible to leak a given amount of an oil from one side of the sealing ring through the crank-shaped oil channel to the other side, thereby preventing the wearing of the shaft member caused by foreign matter, such as an iron powder, contained in the oil.

Abstract: A variable force cylinder device with a piston reciprocated by a pressurized fluid in a cylinder chamber, in which the piston has a large-diameter portion and a small-diameter portion, the cylinder chamber has a large-bore portion corresponding to the large-diameter portion of the piston and a small-bore portion corresponding to the small-diameter portion of the piston, and a variable force mechanism is provided for varying a pressure-receiving area of the piston under an interaction of the piston with the cylinder chamber varying depending on the phases of the piston stroke.

Abstract: A pump for the hot chamber die casting of corrosive light alloys including a body (2) wherein a cavity (3) is formed in which a piston (4) vertically reciprocates and on whose side wall (5) an opening (11) for the introduction of the molten alloy (1) and the mouth of a sprue (9) for the connection with the mold (10) are formed. The diameter of the piston (4) is smaller than that of the cavity (3) so that it may move without rubbing on the wall (5) as it is guided by a seal packing (6) detachably constrained to the mouth of the cavity (3), the opening (11) being closed during the compression of the alloy in the cavity (3) by a valve (12) controlled from outside through a lever (13).

Abstract: A severe service compressor for the reliable compression of dirty gasses using compressors with seals cooled by the hydraulic fluids doing the work of compression and seals isolated from the high temperatures of the compressed gasses by piston rings which restrict the flow of compressed gasses into the area adjacent to the seals on the compresion stroke and allow the venting of the gasses adjacent to the seals on the reverse stroke.

Abstract: A low blow-by compressor has a piston with at least one first ring disposed at the top end thereof and at least one second ring disposed at the bottom end thereof. A port is formed in the cylinder such that the port is above the second rings when the piston is positioned at top dead center and the port is below the first rings when the piston is positioned at bottom dead center such that fluid which blows by the first rings tends to exit the cylinder through the port rather than to blow-by the second rings. Thus any fluid which blows by the first rings can either be exhausted or recycled through the compressor inlet. The compressor utilizes reed valves wherein a first valve plate is attached to the cylinder and a second valve plate is disposed in laminar juxtaposition to the first valve plate. A reed valve gasket assembly is disposed intermediate the first and second plates and an o-ring is disposed about the periphery of the valve reed gasket assembly to prevent fluid leakage therethrough.

Abstract: A contact-less seal apparatus including a first surface and a closely adjacent second surface with a space defined therebetween. A high pressure fluid region exists on a first side of the space. A low pressure fluid region exists on a second side of the space. A plurality of discrete expansion chambers are integrally formed in at least one of the first and second surfaces within the space to limit fluid flow from the high pressure fluid region to the low pressure fluid region. The expansion chambers may be formed on an axial end of a rolling piston, side and end faces of a vane, lateral faces of a reciprocating piston or other elements where a contact-less seal is highly desirable to improve sealing capability and effectiveness.

Abstract: Vehicle suspension apparatus operating between the sprung and unsprung masses of a vehicle includes a pendular anti-roll bar connected to the vehicle, and a pair of links which connect the bar to the wheels. One and the other link, respectively, is extensible and inextensible, with the extensible link comprising a selectively controllable hydraulic piston-cylinder assembly having first and second flow paths, and valve means which upon command automatically locks the piston at a midstroke position, depending on the flow of fluid in the passages. The flow paths allow the user to select either of two roll stiffness levels (i.e., high and low) and provide automatic convergence of the piston to its locked midstroke position (high roll stiffness hard ride) upon command.

Abstract: A linear actuator used in moving, for example, gate valves, sluice gates and the like, wherein an increased thrust is required during initial movement. The present invention includes, as part of the linear actuator, a novel booster piston movably disposed about a piston rod; further included on the booster piston is a thrust column disposed radially between the booster piston and the piston rod so as to define an annular fluid channel for enabling fluid to move upwardly so as to contribute a substantial additional thrust component to move the primary piston.

Abstract: A piston-cylinder assembly in which the piston includes two piston heads connected together in spaced relation by a stem and cooperable with two portions of the cylinder, dividing the cylinder into a working chamber on one side of the first piston head between it and the end wall of the cylinder, a drive chamber on the opposite side of the second piston head communicating with the drive, and an intermediate chamber between the working chamber and drive chamber. The first piston head defines a clearance seal with respect to the first portion of the cylinder, and the second portion of the cylinder guides the reciprocatory movements of the piston. The intermediate chamber includes a semi-permeable seal between the cylinder and piston, which seal is permeable by gas but impermeable by liquids, to thereby prevent the passage of liquid from the drive chamber through the intermediate chamber to the working chamber.

Abstract: The invention concerns a tilt correction system with at least one pair of cylinder and piston assemblies which are hydraulically operated. The extent of tilt correction is limited by grooves internal to the cylinders of the assemblies which short hydraulic potentials once the pistons of the assemblies have moved from a rest position to a position adjacent the grooves. A preferable arrangement includes connecting each assembly between an anti-roll bar and an axle.

Abstract: In a free piston engine, to reduce dynamic loads on the reciprocating elements caused by a time varying pressure gradient across the gas bearing and close clearance seals provided therein, drain galleries are incorporated at the ends of the gas bearings to isolate the same, and circumferentially spaced grooves are incorporated in the close clearance seal region.

Abstract: Gas cushions are maintained between a piston and a cylinder of a gas lubricated reciprocating engine which are effective in retarding the approach of the piston to the cylinder wall under the thrust of side forces from the connecting rod. The cushion are maintained by viscous flow forces for sufficient time exceed a half cycle of crankcase rotation.

Abstract: Hydraulic fluid is replenished in a pulsator chamber of a fluid driven pulsator pump by having the power plunger in an upstanding bore with spaced seals. The power plunger is withdrawn upon each stroke vertically upward. As it is withdrawn past seals, any gas within the pulsator chamber may be purged or bled into an annular space and there out into a reservoir and scrubbing chamber. Additional hydraulic fluid will flow into the pulsator chamber. Upon the down stroke of the plunger an exact amount of volume will be displaced within the pulsator chamber. Adjustment of the product pumped on each stroke is by sacrificing a measured amount of the pulsator liquid into a sacrifice chamber. The amount of liquid which flows into the sacrifice chamber upon each down stroke and out of the chamber on each upstroke is adjusted by adjusting the movement of a floating piston by a micrometer rod.

Abstract: In order to check the operation of high-voltage electric circuit-breakers, proximity detectors are housed in through-bores pierced in the wall of the hydraulic jack cylinder, the through-bores being disposed in spaced relation over a distance corresponding to the range of travel of the jack piston. Since no provision is made for any piston ring or packing seal, the jack piston is not damaged as it passes against the outlets of the through-bores on the internal surface of the cylinder. The output signals of the proximity detectors are applied to a unit for measuring and controlling the position of the piston within the cylinder.

Abstract: A method of hardening a sucker rod well pump has a step of forming a boronized case on the plunger. Then the plunger is heated and quenched to form a hardened steel supporting layer. A chromium case is formed on the barrel.

Abstract: A piston engine comprising a piston movable in a recriprocating manner in a cylinder, while during operation a wedge-shaped gap is present between piston and cylinder. The piston divides the cylinder into a first chamber and a second chamber, which communicate with each other through the gap. A stable central position of the piston is obtained by means of the wedge-shaped gap, which mainly determines a pressure difference between the first chamber and the second chamber. A particular application of the piston engine is a cryo-cooler, by means of which, for example, processors of computers are cooled.

Abstract: A clamping mechanism which includes a cylinder and a piston. The diameter of the piston is less than the internal diameter of a rear chamber of the cylinder such that fluid flows around the piston when the piston moves from an open position to an intermediate position. The diameter of the piston is equal to the internal diameter of a front chamber of the piston such that fluid cannot flow around the piston when the piston moves from the intermediate position to a closed position. To prevent cavitation within the cylinder, fluid is charged to the cylinder in accordance with the movement of the piston.

Abstract: A gas compressor for use in a gas refrigerator includes a compression space having a volume varied with a positional shift of a piston when the latter reciprocates in a cylinder, a first buffer space communicating with the compression space in one direction with respect to the compression space and a second buffer space communicating with the compression space in the opposite direction. Forces acting on working surfaces of the piston are set in such a way that, when a reciprocation stroke of the piston is to be lengthened, a shift of a neutral position of the piston reciprocation toward the compression space is prevented and, when the reciprocation stroke is to be shortened, a shift of the neutral position away from the compression space is prevented, so that the dead space in the compression space is minimized and a highly efficient operation can be realized in a wide output control range.

Abstract: A closing mechanism of an injection molding machine has a piston-cylinder unit to be pressurized hydraulically. Two partial strokes can be carried out in the unit, of which the first can be run through faster than the second. A displacement tube (7) extends into a main cylinder chamber (6) and into an inner cylinder chamber (4) of a piston (2) of the piston-cylinder unit. The displacement tube (7) is fastened to an end wall of the main cylinder (1) and is open at its free end. The piston (2) is designed as a plunger and is spaces on all sides from the cylinder wall (5) of the cylinder (1) of the piston-cylinder unit. The piston (2) is guided in a flanged gland (15) which is screwed to the cylinder (1).

Abstract: A cryocompressor includes a check valve arranged in a circuit connecting a compression chamber defined by a piston disposed in a cylinder with an annular gap small enough to provide an expected sealing effect to a buffer chamber also defined by the piston in the cylinder, a cross sectional area of the annular gap between the piston and the cylinder being larger on the side of the compression chamber than on the side of the buffer chamber.

Abstract: The invention, a high-pressure, reciprocating, gas compressor, employs labyrinths to create gas sealing, annular, air dams between the piston and cylinder bore, and piston rod and an aperture in an end wall or closure of the cylinder through which the rod translates, and active magnetic bearings to maintain the piston and rod at their centroids, equally and minutely spaced, fully thereabout, within the bore and aperture. Too, the drive mechanism, a scotch yoke arrangement, has further, active magnetic bearings, to centralize a drive shaft in its housing, and to effect a non-contacting travel of the drive shaft's offset crank, which translates the piston rod, within the yoke.

Abstract: The present invention relates to a cryopump having a gas bearing formed in a clearance seal between a piston and a cylinder. The gas bearing is formed by forcing pressurized gas from a gas plenum through orifices to the clearance seal.

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: A free-piston Stirling machine has a piston which can reciprocate and also rotate within a cylinder and which is supported and centered in the cylinder by a grooved dynamic bearing, the piston having two end faces which are acted upon during operation by different fluid pressures. The piston includes at least one sealing part having a circular-cylindrical smooth sealing surfaces and at least one bearing part which is provided in its peripheral surface with a groove pattern. The length of the sealing surface and the size of the gap between the sealing surface and the cylinder wall are selected such that the pressure difference across the bearing surface is reduced so that the piston remains free of radial dynamic instability during operation.

Abstract: An improved pump is provided for pumping non-lubricating fluids at extremely high pressure while reducing galling and wear on components such as pistons and cylinders. The reduction in component wear and galling is achieved by modifying the piston-cylinder combination to provide a pressure area and a centering area that is axially displaced from the pressure area of the piston-cylinder combination. The pressure area of the piston-cylinder combination is modified by reducing the diameter of the piston or increasing the inside diameter of the cylinder or both to provide a 0.1 percent to 2.5 percent increase in clearance at the pressure end of the piston-cylinder combination than is provided at a centering area. The advantages of the invention are further enhanced by employing a release area disposed intermediate the pressure area and the centering area of the piston-cylinder combination.

Abstract: A self-priming pistonless lift pump has a first elongate tubular cylinder within which a second elongated tubular cylinder is loosely contained and freely slidable, the respective cylinders having inlet valves at their lower ends, and at their upper ends having fluid outlets, the outlet of the second tubular cylinder being transversely aligned with the outlet of the first cylinder when the second cylinder is in a lowermost position of travel within the first cylinder.

Abstract: A bore hole pump which eliminates the need for a piston sealingly engaging with the walls of the pump body. The pump comprises a hollow body closed at its lower end by a non-return inlet valve and slidably and sealingly supporting at its upper end, via a seal, a reciprocating riser pipe which is likewise closed at its lower end by a non-return valve. Upward movement of the riser pipe causes fluid to be drawn into the pump body via inlet valve while downward movement of the riser pipe causes fluid to be expelled from the pump body via outlet valve.

Abstract: This invention provides a seal mechanism between two mating surfaces by means of a progressively, but not necessarily uniformly, decreasing clearance gap between said two surfaces for the flow of leakage of liquid and which gap may change as a function of the pressure of the flow.

Abstract: A tandem piston arrangement for a compressor, especially for a dry-running compressor for the high pressure compression of gases such as oxygen, has one piston of the common rod form as a guide piston with piston and guide rings in engagement with the respective cylinder, and at least one other piston as a contactless piston. By thus moving the guide point of the rod with the contactless piston, the length of any vibratile portion of the rod carrying the contactless piston remains constant during reciprocation of the assembly and the vibratile natural frequency thus does not change during operation.

Abstract: A single cylinder pump for circulating cleaning fluids through a radiator or like cooling system applies positive and negative pressure to the fluid to create a pulsating agitation of the fluid through the radiator through the use of a thin washer-like plate which is reciprocatively driven within the cylinder. The washer-like plate is slightly smaller than the cylinder and is separated from the inside of the cylinder by a small annular clearance thereby eliminating the need for lubrication and permitting the pump to be self-priming and to release gases generated by the agitation of the fluids.

Abstract: Passage means is provided for a hydraulic unit, in particular, a hydraulic unit including a plunger slidably fitted in a housing, a chamber formed with the housing and having a wall surface against which the plunger may abut, and a flow path opening into the surface which may be abutted by the plunger for communication with the chamber. The passage means is effective to maintain a communication between the chamber and the flow path. In accordance with the invention, a cap, which is separate from the plunger, is formed with a communication path and is fitted over the plunger to maintain a communication between the chamber and the flow path therethrough.

Abstract: A rugged lightweight valveless plunger (38) is provided for use in a well pumping system of the free plunger type. The plunger (38) comprises an elongated cylindrical integral aluminum body (42) having a rigid sealing section (44) formed by a plurality of circumferential grooves (46) defining a plurality of annular sealing flanges (48). The flanges (48) and grooves (46) are uniform and closely spaced. A pair of annular steel collars (50, 52) are secured to the aluminum body (42) on opposite longitudinal sides of the sealing section (44) and have an outer diameter substantially equal to the outer diameter of the annular sealing flanges (48). The aluminum body provides lightweight and ease of machinability. The collars (50, 52) protect the annular aluminum sealing flanges (48) from frictional wear against the well tubing (20), such that sealing tolerances are maintained over an extended life rating. The plunger (38) is simple in construction and virtually indestructable.

Abstract: A sealing arrangement for a rectilinear reciprocable piston within a cryoic refrigerator comprising a buffer defined by dual O-rings disposed around the circumference of the piston and containing pressurized gas of the same type as the refrigeration gas. The buffer limits or prevents both the entrance of contaminants and also the escape of the refrigeration gas.

Abstract: A hydraulically operated actuator employs multiple metal-to-metal static seals to isolate the hydraulic fluid and to isolate the actuator from surrounding contaminating (ambient) fluids. A housing contains at least two linearly spaced apart chambers. A piston reciprocates from a retracted position to an extended position (power stroke) and from the extended position to the retracted position (return stroke) in one of the chambers (hydraulic chamber). The hydraulic chamber is separated by the piston into two sections, one of which contains high pressure hydraulic fluid and the other of which contains low pressure hydraulic fluid. A first static metal seal ring unit is designed to seal first at the completion of the power stroke of the piston to isolate the low pressure hydraulic fluid section from external contaminating fluids which may be at a higher pressure.

Abstract: An internal combustion engine is illustrated having an engine block, a cylinder located in the engine block, and a cylinder head defining an end wall of the cylinder. A piston is housed in the cylinder and defines with the cylinder and the cylinder head a combustion space adapted to receive a mixture of fuel and air therein. The piston is reciprocably movable toward the cylinder head to compress a fuel mixture in the cylinder and movable away from the cylinder head, the piston engaging one side of the cylinder as the piston moves toward the cylinder and engaging an opposite side of the cylinder as the piston moves away from the cylinder head. The piston includes an annular groove, and the piston ring is housed in the annular groove, the piston ring including opposite ends being spaced apart and forming a gap.

Abstract: A material moving apparatus, and in particular, a material moving pump such as a manure pump. The pump includes a pumping chamber defined by interior chamber walls, and a piston or ram mounted for reciprocation in the chamber. The ram has side walls generally in conformance with the shape formed by the interior walls defining the chamber. The side walls of the ram are slotted or provided with grooves which induce turbulence in fluid flow between the side walls of the ram and the interior walls of the chamber to inhibit backflow of material from a position in front of the ram to a position behind the ram. The pump thus operates efficiently to pump material of low viscosity or material of low density.

Abstract: This invention effects a significant reduction in leakage along a piston reciprocating in a cylinder and having a high fluid pressure differential existing between one end of the piston and the other. A large number of closely spaced, annular grooves are provided on the periphery of the piston and the clearance between the non-grooved piston diameter and the interior wall of the cylinder is maintained at a value significantly larger than that commonly employed between a smooth cylindrical shaft and a cylindrical interior sealing surface. The employment of such unexpectedly large clearance not only provides reduced fluid leakage for lighter density fluids when the equipment is relatively new, but the leakage becomes substantially less than that encountered in a smooth surface bearing construction as the piston and cylinder surfaces wear and increase the clearance.

Abstract: An internal fluid communication system in combination with a fluid operated power cylinder, such as that used on industrial lift trucks, in which a pair of tubular sections in telescopic relationship is disposed lengthwise within the power cylinder, forming a fluid passageway through the cylinder for transmitting fluid from one end of the cylinder to the other. The cylinder may be of either the ram or the cylinder and piston type. Two or more tubular sections may surround the first tubular section and form a plurality of parallel fluid passages passing through the power cylinder from one end to the other without communicating with the operating fluid in the cylinder. In the embodiment of the invention applicable to a cylinder and piston type hydraulic motor, one tubular section is disposed in the piston rod and the other tubular section passes through the piston and is in telescopic relationship with the tubular section in the piston rod.

Abstract: A pneumatic actuator in which a piston and a cylinder define an annular gap therebetween axially connecting two portions of the cylinder cavity otherwise separated by the piston. When compressed air is admitted to one of the cavity portions, an O-ring in an annular groove of the cylinder wall is expanded by the compressed air and seals the gap, and the piston is moved against the restraint of a strong compression spring. When the air backing the O-ring is vented, the air pressure in the cylinder drives the O-ring back into the groove, and air thereafter escapes quickly from the one portion of the cavity through the gap and into the other cavity portion which is open to the atmosphere. The resulting quick movement of the piston by the expanding compression spring is transmitted to a device outside the cylinder for operating the same.

Abstract: A pneumatic ejector device suitable for use in an aerial bomb ejection system, in which pivotably operable jaws for gripping the bomb or other device are operatively interconnected to a pneumatically operated piston which engages with the bomb to effect positive release. The piston is contained within a gas tight cylinder and a radial clearance is provided therebetween to allow for gas leakage to both sides of the piston. The piston is locked in the loaded position by means of a spring and ball detent and is "armed" by charging air or other gas under pressure into the cylinder. Ejection is achieved by releasing gas pressure from the lower side of the piston at a rate in excess of the rate of leakage past the piston, by means of a solenoid controlled release valve.

Abstract: The support jack comprises a cylinder and a piston which define therebetween a variable-volume chamber. An inlet aperture and an outlet aperture for control fluid are provided for the chamber. Escape passageways are provided in evenly-spaced relation about the rod of the piston and put the chamber in communication with the annular space between the fixed and moving component parts of the jack and open radially onto said space. These passageways create pressure drops which are higher than the pressure drops due to the annular space.

Abstract: A thermally sensitive actuator consists of a pressure cylinder comprising a tube, two end closure elements each secured to a respective end of the tube, a body of flowable material contained within the tube between the end closure elements, and a piston extending through a through-bore in one of the end closure elements and projecting into the body of flowable material. During assembly, the said body of flowable material is disposed within the tube between and abutting said end closure elements, while at least one of said end closure elements is not secured to the tube, so that said body of flowable material determines the distance apart of said end closure elements. The end closure elements are secured to the tube by displacing the peripheral edges of the ends of the latter inwardly.

Abstract: A woven seamless sleeve including axial yarns forms the inner face of an epoxy resin cylinder for an air operated linear actuator. Under certain conditions, a minute, internal, spiral groove develops in applying the resin. In the operation of the actuator the groove serves to retain lubricant.

Abstract: A liquid cryogen pump in which liquid is maintained on both sides of the pump piston during operation. In the preferred embodiment, vapor, when present in the pump chamber, is passed from in front to behind the piston by providing a predetermined clearance between the piston and the cylinder in which it is reciprocated. The clearance is preferably large enough to pass enough liquid cryogen to maintain the desired head of liquid behind the piston. In the embodiment set forth, the pump is arranged so that it can be immersed in the liquid cryogen to be pumped with its pumping chamber and valves at or close to the bottom of the liquid cryogen supply. Heat transfer between the warm, upper end of the pump and its cold end is effectively restricted, and, preferably, the warm end is connected to the cold end of the pump by thin-walled tubular members formed of low thermal conductive materials to minimize heat transfer by conduction.

Abstract: A piston for use in a hydraulic or other fluid operated device having sealing means intended to prevent the passage of working fluid between the piston and cylinder in which it moves consisting of the combination of at least one O ring or other sealing device arranged around the circumference of the piston and left and right hand intersecting helical channels formed over the length of the surface of the piston wall between the sealing device and the end of the piston subject to pressure of the working fluid. The helical channels act both to retain lubricating fluid and to provide a partial seal against the passage of working fluid between the piston and the cylinder, substantially complete sealing being effected by the sealing device.

Abstract: A compressed air engine having specially designed cylinder heads and piston configurations in order to reduce friction and maximize the application of air from a pressurized air source. The disclosure includes a lubrication system whereby the mechanical parts receive oil via a lubrication arrangement including a conveyor chain continually bathed in oil.

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.