Abstract: The present disclosure is to provide a piston assembly in which a particle does not leak out of a cylinder, and including, in an embodiment, a piston body; a piston rod connected to the piston body; a first groove formed in an outer surface of the piston body; and a particle discharge flow path extending from an internal space of the piston body to the outer surface of the piston body.

Abstract: A piston assembly including a shaft having a piston arrangement. The piston arrangement has a retract-area on one side and a extend-area on the opposite side. The retract-area is larger than the extend-area so that when fluid exerts a force on the retract-area the piston arrangement generates and applies a retract force to the shaft. Upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft. The retract force is greater than or equal to the extend force.

Abstract: A piston assembly for a nailer is provided, and includes a piston body with an upper surface, a lower surface and a peripheral edge. A peripheral gland is located between the upper and lower surfaces, the gland having an inner closed end and defining an annular space. An annular piston seal is disposed in the gland, and a plurality of spaced air ports are disposed adjacent the peripheral edge, the ports each being in fluid communication with the gland. The gland and the seal are dimensioned so that during a power cycle of the nailer, pressurized air generated during a fastener driving stroke enters the ports and radially expands the seal for enhancing friction between the seal and a surrounding cylinder. During a return stroke, the seal is radially retracted within the gland to reduce friction between the seal and the cylinder.

Abstract: A piston, e.g., for a control valve in a vehicle compressed air system, is housed in a cylinder in an axially displaceable manner along a longitudinal center axis separating a first cylinder chamber and a second cylinder chamber. The piston has a peripheral annular groove of approximately rectangular cross-sectional in which a sealing ring is inserted, the free end of which is disposed on the inner cover surface of the cylinder. The sealing ring defines, together with at least one groove wall, at least one pressure support chamber. The piston also comprises, in the region of the annular groove, at least one axial opening, which joins the at least one pressure support chamber to the associated first or second cylinder chamber. A pneumatic or hydraulic connection independent of any geometric deformations of the sealing ring is enabled between at least one cylinder chamber and the associated pressure support chamber.

Abstract: A piston is disclosed. The piston may have a piston crown having a top surface. The piston may also have a first land disposed in the piston crown adjacent the top surface. The first land may have a side surface disposed generally orthogonal to the top surface. Further the piston may have a second land axially separated from the first land. In addition, the piston may have a groove disposed between the first land and the second land. The piston may also have a notch extending between the side surface and the top surface. The notch may have a generally concave shape and may extend circumferentially around the top surface.

Abstract: A piston pump is provided comprising a cylinder with an inner cylinder wall and a working space. The piston pump includes a piston inside the cylinder and has a piston head with a first and second projections extending from its lateral surface to the cylinder wall. These first and second projections enclose a cavity between the piston head and the cylinder wall. The piston head also includes a channel for routing a flushing fluid to the cavity. The first and second projections are configured to promote flow of the flushing fluid out of the cavity and into the working space of the cylinder.

Abstract: The invention relates to a piston having a first face, a second face opposite to the first face, a third face connecting said first and second faces together and presenting a groove, and a sealing gasket housed in said groove. The piston includes a duct constituted by a first segment situated inside the piston and connecting said first face to said groove, by a second segment situated inside the piston and connecting said second face to said groove, and by an intermediate segment connecting together said first and second segments and crossing said groove, the walls of said intermediate segment being formed by the walls of said groove and by said sealing gasket in such a manner that said intermediate segment forms a leaktight tube that opens out solely via the first segment and via the second segment, said intermediate segment presenting at least one obstacle suitable for impeding the flow of fluid that flows along said intermediate segment.

Abstract: A pump including a pressure compensated piston is disclosed. In some embodiments, the pump includes a piston with an annular body and an annular sealing element disposed radially outward of the annular body. The annular body has a radially-facing outer surface adjacent an inner surface of the sealing element and an axially-facing surface with an inlet port. A flowpath extends between the inlet port and the radially-facing outer surface of the annular body.

Abstract: A piston is disclosed that includes a longitudinal passage disposed between outlets on the opposing faces of the piston, and a radial passage extending from a node with the longitudinal passage to an outlet on the annular wall between opposing piston seals. Check valves are disposed in the longitudinal passage between the node and each of the piston faces, such that each of the check valves enables fluid flow from its inlet to the outlet on the annular wall, and block fluid flow from the outlet on the annular wall to the inlet. In the event of pistons in a fluid system becoming out of phase with each other, fluid may be admitted through the inlet of the longitudinal passage and the respective check valve and out a side wall outlet, thereby bypassing the piston to exit via the respective end port, until another, out-of-phase piston or pistons in the system also reach full extension or retraction, automatically returning all pistons in the system to be in phase with each other.

Abstract: A packing stack for a reciprocating piston pump is formed of alternating V's of UHMWPE and either a polyurethane thermoplastic elastomer or an olefinic thermoplastic elastomer.

Abstract: A gas-actuated reciprocal drive apparatus has a double-acting piston in a pneumatic cylinder having a chamber at each end. Gas from an area of higher pressure in a compressed gas system flows into a first chamber, while the second chamber is in fluid communication with an area of lower pressure in the gas system. The piston moves toward the second chamber, purging gas therein back to the lower-pressure area in the gas system, without any venting to the atmosphere. A four-way gas valve reverses the piston motion after each stroke, by reversing the chambers' gas connections.

Abstract: A method and device for forming a sliding seal between a reciprocating piston (22) and the wall of a cylinder (8), wherein one side of the piston faces a first liquid in a pump chamber (26) of the cylinder (8), a first piston seal (24) and a second piston seal (58), spaced from the first piston seal (24), sealing between the piston and the cylinder (8); and wherein a second liquid is supplied under pressure between the seals (24, 58), the pressure of the second liquid between the seals (24, 58) being maintained at a level essentially equal to or slightly lower than the pressure of the pump chamber (26).

Abstract: A hydraulically and/or pneumatically actuated cutting tool is provided having a housing with a piston assembly slidably disposed between a fluid inlet and a fluid outlet. The piston assembly comprises a seal which is operable between two positions. In a first position the seal produces a substantially water-tight seal between the piston and the interior surface of the housing. As a result, fluid entering the chamber through the fluid inlet advances the piston assembly toward the fluid outlet. In a second position a gap is formed between the seal and the interior surface of the housing such that fluid communication is established between the fluid inlet and the fluid outlet. As the fluid is removed from the housing through the fluid outlet, a spring biases the piston assembly back to its original resting position.

Abstract: A pump comprises a housing having a fluid inlet and a fluid outlet. A piston is mounted for reciprocating motion in first and second directions within the housing. The housing has first and second cavities on first and second sides of the piston, respectively. The first and second cavities are fluidly coupled to the fluid inlet and fluid outlet, so that fluid is pumped to the fluid outlet when the piston moves in either of the first and second directions. A bleed valve is coupled between the first and second cavities. The bleed valve has first and second closed states and an open state. The bleed valve changes from the first closed state through the open state to the second closed state when the piston moves in the first direction. The bleed valve changes from the second closed state through the open state to the first closed state when the piston moves in the second direction.

Abstract: A hydraulic master cylinder having a cylinder body (1) with a piston (3) slidable therein. The piston carries a sealing assembly (20) to permit pressurization of a pressure chamber (6) and fluid recuperation upon retraction of the piston. The sealing assembly includes a first seal (23) of relatively hard material slidable against the internal cylinder wall and a relatively resilient second seal (25) arranged to act between the sealing surfaces of the piston and the first seal to provide a fluid tight pressure seal during pressurization of the chamber.

Abstract: The invention relates to a hydraulic drive system comprising a plurality of hydraulically driven piston units with cam rollers, which are disposed to act against a wave-shaped cam profile of a cam curve element, so that linear movement of the cam rollers against the cam profile produces a relative driving movement between the cam element and the piston units. The characterizing feature of the invention is that the drive system is composed of separate, assembled cam curve element modules and separate assembled piston units.

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

Abstract: An rotary internal combustion engine consisting of a rotatable cylinder made up of fuel charge and multiple working segments rotating in unison. The fuel charge and working segments each contain a plurality of radially arranged cylinders open at both ends and a spherical piston in and freely movable within each of the cylinders. A stationary cam surrounds the cylinder having cam surfaces to contact the spherical pistons within each of the cylinders causing each piston in its respective cylinder to reciprocate as the cylinder rotates. A stationary core is located within and enclosed by the rotatable cylinder for supplying and carrying away working fluid into and from the cylinders as well as igniting and delivering fuel charge to the working segments. An alternative embodiment consists of a sealing arrangement between the pistons and cylinders utilizing rings with pressure balancing to reduce friction.

Abstract: An elongate tank for transport or for storage in bulk of semisolid and fluid materials, such as grease and oil. The tank has an outlet at one end thereof for discharging material contained therein, and has a generally cylindric interior surface. A generally cylindric piston is sized to slide in the tank and is movable in a direction toward the outlet thereby to place material in the tank through the outlet. The piston comprises a piston member and an elastic annular seal carried in a circumferential channel around the piston member. The seal has an annular base and an annular crown disposed radially outwardly of and joined to the base with a fluid chamber between the base and crown. The seal is expandable by introducing fluid into the fluid chamber.

Abstract: An engine (40) comprising a piston (2); a top ring (3) and a second ring (4) attached to the piston (2); partitioning members (9)(10) attached to the piston (2) and connecting the top ring (3) and the second ring (4) so as to form a gas chamber (8) at the side surface of the piston (2); a gas passage (15) for communicating the gas chamber (8) to an upper surface (7) of the piston.

Abstract: A piston apparatus for use in a controlled deflection roll includes a rectilinear-shaped piston having at least one side seal extending longitudinally in a slot in each side wall and an end seal in each end of the piston extending between the side seals. The end seals have at least one pair of intersecting surfaces at each end thereof which cooperate with a corresponding pair of surfaces of each side seal to move longitudinally relative to the piston and side seals to maintain a continuous seal peripherally about the piston. The continuous seal engages the side walls of a channel within the support shaft of the controlled deflection roll and a non-movable seal surface in each of two, opposed dams at either end of the channel in the support shaft. The side and end seals move with the piston relative to the support shaft and seal surfaces on the end dams.

Abstract: A continuous seal ring member fitted in a ring groove of a piston of a compressor. The seal ring member has a washer-like initial shape with an internal diameter smaller than an outer diameter of the piston, whereby the inner peripheral portion of the seal ring member is expanded when the seal ring member is fitted in the ring groove. The outer peripheral portion of the ring seal member is then axially and inwardly collapsed relative to the inner peripheral portion thereof so that one of the side surfaces of the initial seal ring member constitutes an outer sealing surface for engagement with the cylinder bore and the outer peripheral portion in the original shape is arranged on the side of said compression chamber.

Abstract: An improved fluid transformer which is capable of controlling the position of the operating pistons within the apparatus so that pressure equilibrium is maintained and the movements of the pistons are limited to predetermined locations within the cylinders. The transformer is capable of operating in a contaminated environment by purging unwanted fluid contamination from the internal workings of the transformer. Dynamic piston and cylinder seals are positioned such that destructive pressure forces are counteracted by opposite frictional forces during operation, thereby allowing the seals to remain effective at high pressures for long periods of time.

Abstract: An air weapon air compression system of the type in which air is compressed in a cylinder and expelled through a discharge port, to propel a projectile along the barrel and fire it out of the weapon, by the rapid movement of a piston within the cylinder. Such a system incorporating grooves in one or both of opposed portions of the cylinder and piston, for the transfer of air towards the discharge port during the final compression stage, to enhance the performance of the weapon.

Abstract: An improved pneumatically operated valve for controlling supply of fluid to a certain apparatus adapted to be operated for an intended purpose using the thus supplied fluid. The valve includes a valve portion on the piston rod and a flow passage of fluid is normally kept in the opened state or in the closed state by means of a the valve portion under the effect of force exerted on the piston in a predetermined direction. When any abnormal fluctuation of pressure of fluid is detected, pressurized air is introduced into the interior on the casing so ast to exert its pressure on the pistion against the aforesaid force of the piston, whereby the flow passage is shifted from the opened state to the closed state or from the closed state to the opened state.

Abstract: The pressure accumulator (10) comprises a cylindrical housing (12) having a bore (14) with a piston received slidably therein. The piston (30) has an H-shaped cross section and includes a reduced diameter portion (34) extending longitudinally along the piston (30), and a sealing device (36, 38) disposed at each end of the reduced diameter portion (34). A cylindrical sleeve (44) is received in the reduced diameter portion (34) such that each end of the sleeve (44) abuts a respective sealing device (36, 38). The housing (12) has an exterior circumferential groove (20) with an O-ring (26) therein, and a radial opening (22) extending between the circumferential groove (20) and bore (14).

Abstract: The pressure accumulator (10) comprises a cylindrical housing (12) having a bore (14) with a piston received slidably therein. The piston (30) has an H-shaped cross section and includes a reduced diameter portion (34) extending longitudinally along the piston (30), and a sealing device (36, 38) disposed at each end of the reduced diameter portion (34). A cylindrical sleeve (44) is received in the reduced diameter portion (34) such that each end of the sleeve (44) abuts a respective sealing device (36, 38). The housing (12) has an exterior circumferential groove (20) with an O-ring (26) therein, and a radial opening (22) extending between the circumferential groove (20) and bore (14).

Abstract: A linear motion damper is disclosed which comprises a hollow sleeve member, a rod reciprocating within the sleeve member, and a piston adapted to engage a fluid filled cylinder to provide resistance to linear motion by the exertion of lateral fluid pressure between the rod and the sleeve. The damper of the present invention exhibits greater efficiency and durability in operation, and is adaptable for a wide variety of applications.

Abstract: A drum brake assembly having a wheel cylinder mounted on arms of a center guide backing plate by means of notches receiving the arms. The cylinder has pistons with low drag O-ring seals in grooves configured to provide seal forces which are aided by brake actuating pressure to assure sealing action. Wiper seals within the wheel cylinder are used in place of boots.

Abstract: The piston has at least one first piston ring groove for receiving a first compression ring and a flame damper ring groove located above said first compression ring for receiving a floating type flame damper ring. According to the invention, on the outer surface of the flame damper ring there is provided a groove adapted to receive a second compression ring having tips defining a gap, the radial thickness of the second compression ring is lower than that of said first compression ring. The second compression ring is so conformed not to close on the tips when subjected to external pressure but to act with its inner surface on the bottom of its groove.

Abstract: A downhole oil well hydraulic pump has a reciprocating piston assembly with a piston ring mounted in a groove around the piston. This piston ring groove has a main portion which loosely mounts a piston ring and an auxiliary portion joining the main portion which accumulates well fluid to lubricate the piston ring during operation of the pump.

Abstract: An internal combustion engine having a gas sealing device including an L-shaped keystone piston ring groove formed on the outer circumferential surface of a piston, and an L-shaped keystone piston ring in pressing contact with the inner surface of a cylinder and fitted in the L-shaped keystone piston ring groove forming a gap for introducing a gas pressure from a combustion chamber into the piston ring groove. The L-shaped keystone piston ring groove includes an outer groove portion underlying a top land formed in the piston, and a wedge-shaped groove portion contiguous with the outer groove portion and tapering in going toward the center axis of the piston. The L-shaped keystone piston ring includes an outer ring portion disposed in the outer groove portion of the piston ring, and a wedge-shaped ring portion disposed in the wedge-shaped groove portion of the piston ring groove.

Abstract: In a pump having a cylinder liner, there is a piston therein, a seal around the piston and rear wearband around the piston body to align the piston within the liner. An elastomeric seal ring is in sealing and sliding contact with the liner. A gap filler, with minimal axial creep and controlled radial creep, abuts the rear surface of the seal and maintains continuous contact with the liner thereby continuously closing the extrusion gap between the gap filler and the liner as the liner wears. The wearband has a plurality of angled grooves longitudinally traversing it. Abrasive particles are directed within and through the grooves in the wearband while a source of liquid is communicated into the piston body, through water channels in the gap filler and through the flowpaths in the wearband to create a vortex action which washes the liner wall. The wearband insures no metal to metal contact between the piston and liner and provides a constant piston gap between the metal piston and liner.

Abstract: A piston seal having two spring tensioned rings which are biased radially toward the cylinder wall and seated in the uppermost one of the ring groove in the piston head. The upper ring has a relatively small and constant thickness of between 0.005 and 0.030 inches and includes a radially extending base seated in the ring groove and an axially extending flange forming an obtuse angle of between 98 and 101 degrees with the base and extending outwardly of the piston head such that fluid under pressure in the cylinder flexes the flange into sealing contact with the cylinder wall. The lower ring functions as a standard compression ring and also supports the thin upper flex ring. The upper flex ring has a predetermined size opening in the base which is aligned with the gap in the compression support ring to provide a controlled "blow-by" to minimize oil reservoiring below the rings caused by the more effective seal.

Abstract: A plunger comprises a carrier and a hollow sleeve portion extending around a portion of the carrier. The sleeve portion rests between longitudinally spaced radial shoulders of the carrier. A portion of the carrier disposed within the sleeve is radially spaced from the sleeve to form a gap, which gap is pressurized to counteract pressures acting exteriorly on the sleeve portion. The gap can communicate with the environment surrounding the plunger so that external pressures pressurize the gap before or during plunger operation. The carrier may comprise a body portion and a cover portion which are connected by means of extensions which project through the sleeve portion. The sleeve portion can be formed of a material having a smaller coefficient of expansion than the body portion or cover portion.

Abstract: A fluid pressure actuated piston that consists of two parts, a metallic portion and a nonmetallic portion, is disposed in a conventional, metallic, cylindrical housing. The non-metallic portion is slidably engaged with the metallic housing. The metallic portion has a clearance to prevent contact with the metallic housing and is connected to the non-metallic portion in such a manner as to provide a recess for a conventional O-ring seal. The recess has metallic O-ring sealing surfaces on both the piston and the housing without any metallic contact to the housing.

Abstract: A piston comprising hydrodynamic skirts and crowns, pressure-actuated sealing rings of fixed excursion or balanced by hydrodynamic reactions, or no rings at all, stringent temperature control, ample oil on the cylinder wall even near top-dead-center, characterized by absence of abrasion between piston and cylinder and much lower friction, resulting thereby in higher fuel-economy and longer engine-life.

Abstract: An annular seal having first and second annular end faces extending substantially perpendicular to the axis of symmetry of the seal, said annular end faces being connected to each other by two axially extending surfaces each having the same axis of symmetry as the seal, one of said axially extending surfaces defining at least in part the surface of a lobe having a summit region, and at least a first of said annular end faces being shaped to define an annular recess.

Abstract: A piston for an internal combustion engine having a double tapered top land to provide controlled variation in the clearance about the head of the piston. The controlled variation in clearance about the piston head provides a sufficiently sized orifice which prevents the formation of hard carbon and improves oil control without greatly increasing pollutants.

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

Abstract: An actuating cylinder for a magnetic rail brake unit on a vehicle has a piston slidable within a cylinder and the piston has an end position at the head end of the cylinder. A pair of concentric conical mating surfaces are provided on the piston and cylinder head end so as to be engageable with each other to stop the piston in the end position.

Abstract: A cylinder housing has a piston projecting from one end thereof for forming a longitudinally expandable ram. One end of the cylinder housing has a base and the projecting end of the piston has a head whereby upon engagement of the base of the cylinder and the head of the piston between the top and bottom of a backcut provided in the tree, the tree can be felled by expanding the ram. The engaging surface between the end of the piston and its head comprises a slidable concave-convex surface engagement to allow relative movement of the head on the piston as the tree falls. The head is held on the piston but capable of its relative sliding movement by a resilient cord connected between it and the base of the cylinder. The piston is hollow to reduce the weight of the unit and employs a novel seal between it and the cylinder.

Abstract: A piston-cylinder assembly having a circumferential groove around the piston near the end of the piston facing the cylinder chamber, a cuff around the piston at a location more remote from said chamber from the groove, a guide ring mounted in the groove for slideably abutting the cylinder wall, the guide ring having a convex inner configuration and a generally cylindrical outer configuration.

Abstract: A molding apparatus for forming articles and especially edible patties from such moldable materials as ground meat, fish and the like in which the apparatus includes a movable mold having a shaping portion therein, pressure means including a pressure chamber for applying pressure to the material therein for forcing the compressed material into the mold and pressure operated seal means communicating with the pressurized material for providing pressure operated seals that substantially prevent escape of the pressurized material from the pressure cavities of the apparatus.

Abstract: A piston and seal assembly is adapted to work in a cylinder, particularly a master cylinder of a vehicle braking system, the seal having a lip which sealingly engages the cylinder bore on the pressure stroke, an inner portion mounted on the piston, and an interconnecting portion between the lip and the inner portion. A retaining member holds the seal on the piston and engages the interconnecting portion during the return stroke of the piston so that the seal flexes about the line of engagement between the retaining member and the interconnecting portion to provide a recuperation flow path between the lip and the cylinder bore.

Abstract: A plunger for a downhole pump having a hollow mandrel with a concentrically arranged resilient cylinder thereabout, with an annular chamber formed between the mandrel and the cylinder. The annular chamber is flow connected to the interior of the hollow mandrel so that pressure which is effected within the hollow mandrel also is effected within the annular chamber causing the resilient cylinder to expand radially outwardly into engagement with the interior surface of the working barrel, thereby more efficiently sealing the plunger to the working barrel.