Abstract: A one-way valve for dispensing fluid assures, after the fluid has been dispensed, that any flow of contaminants into the source of the fluid is prevented. The one-way valve has a disc shaped valve body enclosed about the circumferential edge by an elastomeric membrane. Separate passageways conduct the fluid through the valve body with the fluid flowing from one passageway to the other between the circumferential edge and the elastomeric membrane. The valve body has a greater diameter than axial length.

Abstract: A pressure responsive spring valve which is able to function at high pressures and temperatures, and can attain a high degree of precision control in a minimum of space, as well as an improved high pressure fuel injector for internal combustion engines which uses such a spring valve to achieve the demanding performance characteristics of the more complex new injector designs within limited space requirements. In all cases, a band-like spring valve member is used to reduce the number of parts and the space requirements therefor relative to that required for a coil spring type pressure control valve.

Abstract: A diaphragm pump has a first fluid-operated valve which opens when the diaphragm performs a suction stroke and a second fluid-operated valve which opens when the diaphragm performs a compression stroke. The volumetric efficiency of the pump is enhanced by constructing at least one of its valves in such a way that the central portion of a resilient disc-shaped valving element, whose marginal portion bears against a seat when the valve is closed, abuts a supporting surface having a diameter selected in dependency on the diameter of the valving element, the thickness of the valving element and the Shore hardness of the material of the valving element in such a way that the selected frequency of the diaphragm in actual use of the pump induces a resonant frequency of the valving element. This also contributes to a reduction of noise and renders it possible to reduce wear upon the valving element and the adjacent parts of the respective valve.

Abstract: An air bag system for an assistant driver's seat comprises a housing including an open face to allow air bag deployment, an air bag folded in the housing, a gas generator secured to the rear wall of the housing opposite to the open face, first outlets formed in the gas generator to allow gases to flow into the air bag stored in the housing, second outlets formed in the gas generator to allow the gases to flow out of the housing, a passage defined in the housing to provide a communication between the second outlets and the outside of the housing, and a release mechanism situated in the passage for allowing the gases to flow from the gas generator into the outside of the housing through the passage when the pressure of the gases flowing through the second outlets exceeds a predetermined level.

Abstract: An airblast fuel injector tip is provided for reducing fuel vaporization problems as a result of high fuel temperatures without adversely affecting the airblast operational characteristics of the injector tip. The injector tip includes a fuel receiving chamber and an arcuate valve member movable relative to a valve seat member having a fuel discharge port for discharging fuel flow into the fuel receiving chamber as metered by said valve member in dependence on the pressure of fuel. The valve member comprises an arcuate reed-type valve received in a generally cylindrical tubular valve seat insert with the flow area of the fuel discharge port adjustable externally of the valve seat insert for adjusting the valve cracking pressure.

Abstract: An air distributing device mounted into the sloping wall of a hopper containing finely divided material, such as flour or cement, aerating and causing the discharge of the material with a pressurized air flow and keeping the material in constant motion toward the discharge outlet of the hopper, the air distributing device being substantially hemi-spherical in form and providing a wide distribution of the pressurized air.

Abstract: A valve assembly which allows air to pass in one direction in a substantially resistance-like manner while preventing the flow of air in the opposite direction. The valve assembly includes a hollow conduit having 1) an interior peripheral surface which defines a flow passage, 2) an exterior peripheral surface, and 3) a radial passage extending through the conduit for communicating the flow passage with the exterior peripheral surface. The valve assembly also includes a continuous recess formed in the exterior peripheral surface of the hollow conduit in the region of the radial passage and a valve positioned within the recess in the exterior peripheral surface and proximate to the radial passage. The valve includes a pressure ring portion and a continuous lip portion pivotably connected to said pressure ring.

Abstract: A fluid dispensing valve is made up of a valve body laterally enclosed by an elastomeric sheath. The valve body is connected to a container from which fluid is dispensed through the valve body. The valve body has an inlet passage for flowing the fluid from the container to a space between the elastomeric sheath and an outer surface of the valve body. An outlet passage through the valve body, spaced angularly from the inlet passage, has an opening through the outer surface of the valve body covered by the elastomeric sheath, so that fluid pressed out of the container can flow between the elastomeric sheath and the outer surface to the outlet passage and then be dispensed from the valve. The valve body can be a flat disk-like member.

Abstract: The invention is directed to a metering device for lung-demand valves and includes prepressure compensation. The metering device includes a valve body coacting with a valve seat for metering gas and a compensating piston is arranged between a primary pressure chamber and a secondary pressure chamber for transmitting the compensating force to the valve body. The compensating piston is guided in a compensating housing. The metering device is improved in that the compensating piston is movable without friction and a seal is easily secured. For this purpose, a membrane made of elastic material defines the seal unit. The membrane is tightly held and has a cylindrical side wall which is fixed in the compensating housing. The membrane has regions of reduced wall thickness on the periphery of the side wall and these regions are subdivided into segments or extend as one continuous portion around the periphery. The regions of reduced wall thickness act as a sealing lip.

Abstract: A liquid driven pump has a driving-liquid accelerating nozzle which opens into a pump chamber having an outlet part positioned coaxially with the nozzle. Opening into the pump chamber is an evacuation line which is intended for connection to a space to be evacuated. The outlet part of the pump chamber discharges into a coaxial drainage chamber and has an abrupt increase in cross sectional area in relation to the outlet part. The drainage chamber has downstream net-like elements which are passed through by the liquid. The relationship between the smallest cross sectional areas of the nozzle and the outlet part respectively and the distance between the nozzle orifice and the drainage chamber are such that essentially the whole of the diffusion process takes place through the agency of the net-like elements. The smallest cross sectional area of the outlet part is from 1.4 to 4.

Abstract: An airblast fuel injector tip is provided for reducing fuel vaporization problems as a result of high fuel temperatures without adversely affecting the airblast operational characteristics of the injector tip. The injector tip includes a fuel receiving chamber and an arcuate valve member movable relative to a valve seat member having a fuel discharged port for discharging fuel flow into the fuel receiving chamber as metered by said valve member in dependence on the pressure of fuel. The valve member comprises an arcuate reed-type valve received in a generally cylindrical tubular valve seat insert with the flow area of the fuel discharge port adjustable externally of the valve seat insert for adjusting the valve cracking pressure.

Abstract: A slit valve medical catheter includes a flexible tube the distal end of which is closed. A length of resilient tubing is mounted coaxially to the distal end segment of the tube so that the tubing extends along the inside or outside surface of the tube. The tubing is slitted lengthwise and an aperture is formed in the tube wall directly opposite each slit with the aperture being wider than the slit so that portions of the tubing wall on opposite sides of each slit overhang the sides of the corresponding aperture.

Abstract: The non-return valve in the air inlet of a pulsating burner includes a flat circular ring of elastic steel. The outer edge of the ring is provided between annular abutment surfaces with a predetermined play. The inner edge of the ring is movable from a closed position to a fully open position in which it has the shape of a truncated cone. The angle between the conical surface of the frustrum and its base is small in the fully open position, on the order of 3.degree., and resistance to opening is extremely small to permit rapid changes between the open and closed positions.

Abstract: An air distributor head mounted in a sloping wall for a hopper for pulverulent material to agitate and aerate the material as it travels down the wall surface toward the discharge opening in the bottom of the hopper; the head assembly including a generally cylindrical head with air flow passages and having an expandable generally cylindrical resilient skirt surrounding the body thus permitting air supplied through the passages under the skirt to be discharged into the pulverulent material to incorporate a flow of agitating and fluidizing air into the material.

Abstract: A dual seal valve having a bubble-tight primary seal and a metal-to-metal secondary seal for sealing engagement with a rotating valve element. The primary seal is preferably a composite seal comprising a relatively hard, high lubricity element bonded to a relatively soft, resilient elastomeric element. The elastomeric element biases the hard element into sealing engagement with the valve element. Several embodiments of the primary seal are disclosed. Tapered inserts are positioned on opposite sides of the valve element, and a seal groove is provided on a tapered outer surface of the insert and adapted for receiving a seal therein. The groove has an enlarged portion which provides a seal relief, allowing deformation and unsealing disengagement of the seal when pressure thereon exceeds a predetermined level. While plug valve embodiments are disclosed, the dual seal arrangement and seal relief are also applicable to ball valves, spherical plug valves, and other valve types having rotating valve elements.

Abstract: The air check valve has a one-piece housing provided with a pair of coaxial passageways and radiating ports which are closed over by an elastic sleeve. When the pressure in the upstream passageway is greater than in the downstream passageway and the crack or opening pressure of the sleeve is exceeded, the sleeve expands radially so as to permit communication between the two passageways for the conveyance of fluid.The air check valve may also be provided with a one-way valve in a partition between the two passageways to permit withdrawal of fluids from a patient.

Abstract: The invention relates to a fuel burner pump assembly of the type having a main regulating valve for controlling a supply of fuel to a burner nozzle and a flow responsive bypass valve for bypassing fluid from the main valve until a predetermined flow rate is achieved. A check valve downstream from the bypass valve and in series therewith has a small predetermined opening pressure which facilitates the operation of the bypass valve. The check valve utilizes a rubber sleeve as the closure member thereof which enhances the operation of the bypass valve by operating to close tightly despite the presence of small dirt particles in the fluid flow.

Abstract: An irrigation leakage prevention device for coupling between an irrigation supply source and an irrigation emitter unit. The device comprises a tubular throughflow conduit, at least the central portion thereof being formed of a resiliently flexible material and having end portions which are held against resilient displacement, a central barrier member being fixedly located within the conduit. With a water supply pressure less than a predetermined minimum, the central portion of the conduit sealingly embraces the barrier so as to prevent throughflow and when the water supply pressure exceeds this minimum, the central portion is resiliently displaced away from the barrier so as to allow throughflow.

Abstract: A valve assembly for a sphygmomanometer controls the inflation and deflation of a pressure cuff. The valve assembly includes an inlet connectable to a fluid pressure source such as a bellows, an outlet which is connectable to a blood pressure cuff, an inlet directional control which actively prevents the flow of fluid from the outlet to the inlet, axial passages which connect the inlet to the outlet, and means for slowly and fixedly or rapidly releasing pressure. The valve assembly may be set to one of three positively located positions: a cuff inflation position, a metered deflation position, or a fast vent position. In the cuff inflation position, fluid pressure delivered to the valve assembly's inlet passes through an inlet directional control to the valve assembly's outlet and on to the pressure cuff which becomes inflated.

Abstract: An O-ring is received in a groove having only an arcuate portion thereof operative to act as a check valve, with the arcuate portion being movable into a chordal recess so that it does not provide full circumferential sealing engagement in the area of the arcuate portion, allowing fluid pressure or flow therethrough so long as the arcuate portion is so displaced. The resilient character of the O-ring urges the arcuate portion back to the closed position along a tapered ramp surface of the recess into which it was displaced when there is no pressure differential acting across the O-ring. Movement of the O-ring support member relative to a fixed surface normally sealed by the O-ring and net pressure forces on the O-ring may also tend to return the O-ring to the closed position in one direction of movement.

Abstract: The valve comprises a valve socket to be mounted in the wall of an inflatable body, e.g. by a snap fastener device, and a valve cap having an internal thread for threaded connection with an external thread on the valve socket. The valve socket includes an air duct with a short duct section which is connected with the outer surface of the valve socket only through a number of narrow ducts discharging at the bottom of an annular groove from whose internal edge a number of radial ducts are connected with a central bore provided in the cap. At the internal edge of the annular groove a pressure sensitive annular sealing member is provided which by the pressure from the outside will be pressed out on a larger diameter in the annular groove. By eliminating the pressure action the sealing member reoccupies its initial position in airtight abutment between the bottom plate of the annular groove and an internal annular surface in the cap.

Abstract: A catheter having a tip which is resistant to plugging by blood components or other body fluids when used as a long term implant within a living body. A check valve is incorporated in the tip that is exposed to the blood stream or other body fluids. The central bore within the catheter is closed at its downstream end. A cross bore or port is provided immediately upstream from the closed end. This cross bore is covered by a thin elastic sleeve to create a check valve. The pressure developed by injected infusate through the catheter opens the valve against the elastic force of the outer sleeve. Fluids cannot enter the catheter either by diffusion against the high velocity exit flow or by suction applied to the proximal end of the catheter.

Abstract: A self-sealing check valve is disclosed for use in the inflation of a catheter cuff. The valve includes a valve housing and a valve element sealingly positioned within the housing. The valve housing has a transversely located fitting for receiving a Luer tip device. A valve element is cylindrical and preferably hollow. A circumferential rim at each end of the element is maintained in a state of compression so that it presses against the inner wall of the housing to form a seal. The element also includes a circumferential channel which is aligned with the Luer fitting. Insertion of the Luer tip device into the fitting depresses the valve element and breaks the seal between the rims and the valve housing wall. This allows fluid flow in either direction through the valve. Resiliency of the valve element causes resealment at the rims when the Luer tip device is removed.

Abstract: A vacuum breaker for connection in the discharge line from a source of liquid. The preferred embodiment comprises an elongated body for connection in the discharge line and opening to atmosphere through a lateral passageway selectively closed by a cylindrical sleeve coaxially carried by said body. In the open position of the sleeve the vacuum breaker is particularly adapted for in-line installation in the drain line of appliances. Various applications for the vacuum breaker are disclosed.

Abstract: A telescopic hydraulic shock absorber for a motor vehicle has a piston with a frustoconical valve element that provides a bypass passage from the rebound chamber to the jounce chamber during a low velocity rebound stroke of the piston with respect to the pressure tube. The frustoconical valve element is constructed to be sufficiently resilient to become seated and close off the bypass passage in response to a relatively high velocity rebound stroke such that all fluid is forced through the rebound ports and the rebound valve to provide higher damping than when the bypass passage is open.

Abstract: A small, reliable diverter valve that maintains a relatively constant flow through a spray nozzle in spite of water supply pressure fluctuations and that positively terminates flow from the faucet spout during hand spray operation. A variable elasticity cup seal keeps constant area passageway to the spray nozzle in spite of water supply fluctuations. A normally open path, moreover, enables air to flow from the spout into the water supply system in conditions of negative supply pressure and thereby assists the cup seal in preventing backflow from the spray nozzle into the fresh water supply.

Abstract: A flow control device which consists of a tubular body having radial sets of orifices therein covered by a resilient member which defines an annular space to which the orifices are connected. The resilient member permits positive pressure to drive fluid through the orifices but prevents negative pressure from sucking air through the orifices. A spring urges the resilient member against one of the sets of orifices.

Abstract: Apparatus for attachment to the side wall of a hopper or bin, having connections to an extenal source of pressurized air, and having an annular orifice internal to the hopper or bin, wherein the annular orifice is covered by a resilient ring, thereby pemitting the flow of pressurized air outwardly through the annular orifice while protecting the annular orifice from contamination and plugging by materials stored in the bin or hopper.

Abstract: A charging fixture for gas charging a damper includes a pair of body members adapted to be forced together under pressure. Alignment pins align the body members as they are forced together. Compressable elastomeric members define a cavity in the body members and are disposed in the body members and sized for compressing and deforming portions of an outer cylinder surface of the damper during charging. A passageway to the cavity is connected to a high pressure source of gas, and the damper is charged by gas entering from the cavity by displacement of a piston rod seal from along an intermediate cylinder head.

Abstract: A rupture disk assembly is provided which after rupture and pressurized fluid relief, recloses itself to prevent backflow therethrough. The assembly is comprised of a hollow rupture disk support member having a pressurized fluid inlet opening at one end and at least one pressurized fluid discharge port at the other end. A rupture disk is sealingly attached to the support member whereby until the rupture thereof, pressurized fluid is prevented from flowing through the support member to the discharge port therein.

Abstract: A pressure relieving device for use with gas flowmeters, pressure regulators and other fluid flow equipment is described. The device includes an O-ring and means for compressing and retaining the O-ring to provide a fluid-tight seal under normal operating pressure, but having a gap positioned such that the occurrence of an excessive pressure causes a portion of the O-ring to move into and through the gap to relieve the excessive pressure. A passage for enabling the fluid to contact the O-ring is sized to allow sufficient flow to relieve a fluid pressure substantially in excess of the normal operating pressure.

Abstract: A valve useful for connecting a source of fluid under pressure to a using apparatus upon actuation of an explosive squib. The connecting structure includes an outer tube of soft material within which there is disposed an additional tube of material having a frangible area. The inner and outer tubes define an annular space and an inner tubular space. One of the spaces is connected to the source of fluid under pressure, while the other of the spaces is connected to the using apparatus. Particularly, the inner tubular space is connected to a source of gas under pressure, while the outer annular area is connected to the using apparatus. Upon actuation of the squib the inner frangible tube is broken at the frangible area upon a bending of the outer tube without its fracturing thereby connecting the source of fluid under pressure to the using apparatus, while at the same time isolating the products of combustion of the squib.

Abstract: Apparatus for injecting ammonia into water, or more particularly, into hard water. Apparatus includes a check valve having a plurality of spaced recessed annuli therearound communicating with an axially disposed bore through orifices or ports interconnecting the bore with the annuli. Annuli profile is characterized by sharp right angle edges defining the outer and inner diameters with no tapered O-ring seat portions therebetween. O-rings are fitted around the annuli in pressure sealing relationship and make line contact only with the outer sharp edges or diameters of the annuli, thus providing a faster responding and more sensitive valve to minor adjustments in ammonia pressure than check valves with tapered seats for the O-rings as well as being devoid of tapered surfaces upon which hard insoluble calcium deposits or scale tend to form when ammonia is added to water.

Abstract: This invention relates to a valve assembly for a pressure-cooker in accordance with the preamble of claim 1.

Abstract: The invention relates to a hydraulic pump or motor having expansible chamber section at one end thereof, which may be a gerator gear set, and a drive shaft at the other end thereof. A distributor valve having a central bore directs fluid between inlet and outlet ports in the housing and the expansible chamber section. The leakage of pressurized fluid into the central bore of the valve causes certain problems including the problem of directly or indirectly causing destructive forces to be applied to the seal provided between the drive shaft and the housing. This problem is addressed by providing check valve arrangements in the housing between the central bore of the valve and the inlet and outlet ports. The check valves open in the direction of the inlet and outlet ports so that when fluid pressure in the valve bore exceeds the fluid pressure in either of the ports, the pressure in the bore is lowered by fluid being forced outwardly through the port having the lower pressure.

Abstract: A mixing valve for use in cementing, fracturing or other treatment of a well. The valve, which may be mounted in a pipe string, comprises a center mandrel surrounded by a coaxial housing having circumferentially spaced apertures therethrough. A packer cup surrounds the center mandrel below the apertures in the housing, and seals the annulus between the mandrel and housing when the pressure of fluid through the bore of the mandrel exceeds that on the outside of the chamber. When mixing fluids, it is only necessary to pressure the fluid outside the housing to collapse the packer cup against the mandrel, the fluid from the outside then entering the stream flowing from the mandrel bore. A method of mixing fluids utilizing the valve of the present invention is also disclosed.

Abstract: A sleeve valve is carried in a parenteral solution administration device. The valve comprises an outer housing (30) defining an outlet tube (28); an inner tubular support (38) defining an inlet tube (45) and a closed forward end positioned within the outlet tube. Lateral aperture means (46) are provided in the tubular support, and an elastic tube (40) surrounds the inner tubular support to cover the lateral apertures. The inner tubular support is free of elastic, tube-retaining structures at its closed end, and is adapted to permit the elastic tube to be laterally slidable on the inner, tubular support through a limited distance. The outer housing defines vanes (44) to limit the lateral advancement of the elastic tube on the support, while shoulder means (42) are positioned about the support to limit the lateral retraction of the elastic tube away from the closed end.

Abstract: A valve assembly having a cylindrical valve chamber with radially directed inlet orifices and with a circular spring leaf which resiliently seals the orifices and which may be deflected by fluid pressure within the inlet orifices to open the orifices. The spring leaf is configured so that it may deflect to open the valve inlet without deviation from its essentially oval shape.

Abstract: Fluid-actuated percussion mechanism includes a housing with an internal cylindrical space receiving a reciprocating piston dividing the space into a working stroke chamber and an idle stroke chamber. The mechanism further includes fluid distributing means mounted in the housing and communicating the chambers and the source of the working fluid. The housing also accommodates a work-performing member adapted to receive impacts from the piston. The distribution means includes at the inlet of at least one of the chambers a valve made in the form of a resilient annular element. The surface of the distribution means has made therein valve seats of which the number corresponds to that of inlets for supplying the working fluid into the chamber.

Abstract: Apparatus for controllably transferring fluid from a pierceable pressurized container includes a valve body, a stem member which is threadably connected to the valve body at one end and a fluid-conducting hose at the other end, and an elastomeric valve ball disposed in a cavity between the body and the stem member. The valve ball controls fluid flow from the container through the valve body and stem member to the hose in response to rotation of the valve stem relative to the body. Simultaneously, the valve balls acts as a check valve to prevent flow of fluid to the container. An O-ring seal between the stem and the valve body is adapted to leak at high pressure and bleed off fluid.

Abstract: Fluid-actuated percussion mechanism includes a housing with an internal cylindrical space receiving a reciprocating piston dividing the space into a working stroke chamber and an idle stroke chamber. The mechanism further includes distributing means mounted in the housing and communicating the chambers and the source of the working fluid. The housing also accommodates a work-performing member adapted to receive impacts from the piston. The distribution means includes at the inlet of at least one of the chambers a valve made in the form of a resilient element. The surface of the distribution means has made therein valve seats of which the number corresponds to that of inlets for supplying the working fluid into the chamber.

Abstract: An endotracheal tube for single use, which is provided, at its end projecting into the windpipe, with an inflatable low-pressure sleeve and has an auxiliary tube which is suitable for inflating the low-pressure sleeve and carries a non-return valve and a relief valve, the relief valve consisting of a hollow body which has a lateral opening, and an elastic tubular skin, which covers the opening, being stretched around the hollow body.

Abstract: A body of electrically insulating material contains a passageway extending completely through the body. The passageway includes a flexible diaphragm dividing the passageway into two compartments to isolate a transducer placed on one side of the diaphragm from direct contact with fluid contained on the opposite side. A pressure relief port, passing from one side of the body to the passageway on the fluid side of the diaphragm, is covered with an "O" ring. Excessive fluid pressure forces the "O" ring away from the relief port to vent the pressure and thereby prevent damaging the transducer.

Abstract: The disclosure of this specification illustrates and teaches the use of a self contained breathing apparatus for attachment to a user's back and incorporates a plurality of tanks having a manifold between them that is common to all with a single filling block leading thereto, and a reserve system mounted at one end thereof. The reserve system comprises a poppet valve which signals a loss in pressure by closing, after which it can then be actuated to open it for supplying the remaining portion of the reserve breathing gas through the manifold.The system also has a first and second stage regulator to provide regulated breathing gas to a user. The first stage regulator incorporates a dynamically balanced piston which is supported by an O Ring or torroidal member that is deformed through its cross section to provide movement to the valving piston. The O Ring is eliptical through its cross section.

Abstract: An inflation guide for permanent mounting on a tire valve for preventing over inflation of the tire.

Abstract: An improved plug valve is of the type that includes a valve body having a bore extending therethrough and a pair of passages intersecting the bore and being substantially normal to the axis of the bore. A valve plug is disposed within the bore for selective rotation between an opened and a closed position to respectively align and misalign a port through the plug with the passages. A first circumferential sealing member between the plug and the bore above the port and the passages and a second circumferential sealing member between the plug and the bore below the port prevents fluid from escaping from an interior of the plug valve and balances fluid pressure acting on the plug. A circumferential sealing device around the top of the plug prevents ingress of foreign matter into the region of the bore above the first sealing member.

Abstract: Unidirectional flow limiter housed in a union between a pipe and a user apparatus, comprising a first channel, a second channel, a flow reduction member between the two channels, a third channel, a non-return valve in the third channel and constituted by a deformable annular member placed concentrically about one of the first or second channels.

Abstract: A master cylinder for a vehicle braking system. The master cylinder including a housing defining a bore therewithin with a piston slidably mounted in said bore. The piston head and the housing bore define a pressure chamber in communication with at least one brake actuator. A conventional annular ring cooperates with the wall of the housing bore and with a radial surface of the piston head for controlling fluid communication between a supply chamber of the master cylinder which communicates with a reservoir and the pressure chamber. The annular ring has a lip which projects toward the radial surface so as to form a non-return valve which prevents fluid communication from the pressure chamber toward the supply chamber when the master-cylinder piston is out of its rest position.

Abstract: The fluid-actuated percussion mechanism includes a housing with an internal ylindrical space wherein a reciprocating piston, which divides the space into a working stroke chamber and an idle stroke chamber, is received. The mechanism further includes fluid distributing means and a distribution unit mounted in the housing for placing the chambers and a source of the working fluid in communication. The housing also accommodates a work-performing member adapted to receive impacts from the piston. The distribution unit includes at the inlet of at least one of the chambers a valve made in the form of a resilient annular element. The surface of the distribution unit has valve seats made in it, the number of which corresponds to that of the inlets for supplying the working fluid into the chambers. The resilient valve element is taut about the surface of the distribution unit in opposition to the inlets and encircles the periphery of the unit.

Abstract: A flexible boot surrounds a piston rod and is sealed at one end to the free end portion of the piston rod and at its other end to the rod end of the associated cylinder. The head end of the cylinder is connected to a source of gas under pressure and the interior of the boot communicates freely with the interior of the cylinder at the rod end thereof. A check valve is provided for relieving the pressure in the boot when it reaches a predetermined value.