Abstract: A combined and integral pump and check valve combination is disclosed herein for the control of fluid flow through a fluid pump portion having an inlet port leading to a gland cavity occupied by a movable sealing element yieldably held in position closing or sealing the inlet port by a self-biasing member such as an open-cell foam material. A retaining ring used during the assembly procedure is disposed between the edge marginal regions of the self-biasing member and the movable sealing element which may function to stabilize the element. A sealed retaining plate is attached to the pump supporting the self-biasing member and the movable element combination and further defines an outlet port or duct on the side of the movable element opposite to its side which is adjacent to the inlet port.

Abstract: The valve assembly comprises a body formed of substantially identical, or identical plates, in which one is the mirror-image or reverse of the other. The plates are held apart, in parallel planes, by an enveloping seal. Each plate is ported for the conduct of fluid therethrough in cooperation with a fluid-conducting void formed in the confronting plate. Flapper-type valving elements are confined within the body, between the plates. A single, centrally-disposed fastener secures the plates and the assembly together, and constitutes the means for the simple disassembly of the unit.

Abstract: A reciprocating pump is provided with a flexible resilient cylinder which is mounted under tension between two end caps. The end caps are adjustably interconnected by means of a plurality of staybolts whereby the longitudinal tension on the cylinder may be adjusted. A piston comprised of a spherical segment is mounted for reciprocation within the cylinder with the spherical surface of the piston disposed in sliding contact with the cylinder.

Abstract: A wear shield attached to a piston in a piston type compressor cushioning impact and reducing friction between the piston and a valve which opens in a direction toward the piston. During some conditions of operation, without the wear shield, a piston can impact the opening valve, which opens interior of a cylinder which holds the piston. The wear shield installed between the piston and the opening valve reduces wear on the piston and on the valve, and also reduces operating noise.

Abstract: The valve arrangement comprises a disc engageable with a valve seat without attachment and a resilient diaphragm engageable with the disc without attachment. The disc completely covers a passage surrounded by the valve seat and flowed through by a fluid. On the side remote from the valve seat, the disc has a central protuberance with cooperates with a central thrust surface of the diaphragm. The disc and the diaphragm are freely movable in a recess adapted to be flowed through by the fluid, the recess being present in a guide member extending around the valve seat. The recess has an inwardly projecting step with which the diaphragm edge part is urged into engagement. This arrangement leads to a flat compact valve with minimum dead space.

Abstract: A reciprocatory piston type compressor is provided with partition walls in a discharge chamber or chambers, the walls being arranged between discharge ports open to the discharge chamber, respectively, to prevent flows of refrigerant gas discharged from the discharge ports from directly interfering with each other at least during the time in which the opening of two adjacent discharge reed valves overlap one another. The partition walls may be formed integrally with a cylinder head of the compressor in such a manner that the partition walls extend centripetally from an inner wall surface of the cylinder head defining the discharge chamber. The flows of refrigerant gas discharged from the two adjacent discharge ports which are open will not interfere with each other but will be guided independently and centripetally along the partition walls in the discharge chamber toward the tops of the partition walls, and then toward an opening that leads to an outer discharge conduit.

Abstract: Noise is caused in a piston type compressor having a valve assembly including reed valves (13F, 14F) and a valve plate (10F) when the reed valves close and strike against the valve plate. The present invention provides a piston type compressor having a valve assembly including an elastic member (21F) and a thin valve sheet (20F) between the valve plate (10F) and the reed valves (14F), so that a shock caused by the reed valves striking the valve plate is absorbed, and the elastic member is protected by the thin valve sheet from damage usually caused by the striking thereof by the reed valves.

Abstract: A multi-piston swash plate type compressor for an air-conditioning system used in a vehicle such as an automobile, including a cylinder block body having a swash plate chamber formed therein for receiving a swash plate and cylinder bores formed therein for receiving pistons which are reciprocated by rotation of the swash plate. The compressor has a suction chamber which is fed with a refrigerant including lubricating oil from an evaporator of the air-conditioning system and a discharge chamber which feeds the compressed refrigerant to a condenser of the air-conditioning system. When the compressed refrigerant is discharged from the cylinder bore into the discharge chamber through a discharge reed valve, all of the discharged refrigerant is impinged on the peripheral and inner wall so as to separate the lubricating oil from the refrigerant, whereby an effective damping and sealing oil layer is formed between the discharge reed valve and the valve seat thereof.

Abstract: A high pressure reciprocating pump has a flange plate or mounting plate secured to the plunger end of a pump drive housing and a suction and discharge manifold is hingedly connected thereto. A stuffing box in bores in the flange plate has a central bore receiving one end of the plunger and forming a plunger pressure chamber coaxial with the plunger. A tapered packing assembly in the stuffing box surrounds the plunger in reciprocal sealing relation. A suction and discharge valve cartridge in one or more valve cavities in the manifold block is coaxial with the plunger. The hinged connection clamps the stuffing box in the flange plate for pivotal movement permitting clear access to the stuffing box and the valve cartridges whereby either may be removed as a unit for easy field maintenance. The valve cartridge comprises a common seat member with a suction valve and a discharge valve movably mounted thereon coaxial with the plunger and positioned concentric and radially spaced on the seat.

Abstract: A reciprocatory piston type compressor having a cylinder block in which a plurality of compression chambers permit a plurality of reciprocatory pistons to be reciprocated so as to compress a refrigerant gas drawn from a suction chamber formed in an end housing into the compression chambers through suction ports of a valve plate, opened and closed by a suction valve mechanism with a plurality of resilient radial suction valves having a free end thereof, respectively, and surrounded by cutoff slots formed in a suction valve sheet, and to discharge the compressed refrigerant gas from the compression chambers into a discharge chamber formed in the end housing through discharge ports of the valve plate, opened and closed by resilient discharge valves.

Abstract: Disclosed herein is a check valve assembly for use in high pressure pumps having a high pressure plunger reciprocating in a pressure chamber or for use in other pressure chambers wherein both fluid inlet check valve means and fluid outlet check valve means are provided adjacent to the pressure chamber. The check valve assembly of the present invention is especially suitable for use in high pressure pumps operating to produce fluid pressures in excess of 10,000 psi, and significantly increases the operating life of the check valve assembly by reducing the incidences of material fatigue caused by cyclic stresses due to cycling high and low pressures.

Abstract: A valve plate for a motor compressor has a continuously smooth figure-eight shaped port for reducing stresses along the primary longitudinal axis of a reed valve associated with the port, and an arrangement for providing a mechanical interlock for a head gasket to inhibit pressure loss between adjacent compressor cylinders.

Abstract: A diaphragm compressor composed of non-metallic parts capable of being manufactured and assembled so inexpensively as to be suitable for one-time use. Conventional expensive fasteners such as screws are eliminated and assembled parts are joined by press fitting, sonic welding or similar inexpensive functionally similar means.

Abstract: In a reciprocating compressor, the separator plate separating the suction and discharge plenums acts as a spring relative to the valve plate assembly. Under liquid slugging conditions the valve plate moves against the biasing force of the separator plate to establish a relief passage between the piston cylinder and the suction plenum.

Abstract: A valve assembly for a swashplate air conditioning compressor comprising a valve plate, discharge valve reeds on one side of the plate and inlet valve reed on the other side of the valve plate, a seal plate located adjacent the outlet valve reeds for sealing high pressure regions from low pressure regions, and retainers securing the valve plate, the valve reeds and the seal plate together in a subassembly, one subassembly being substantially interchangeable with a second subassembly at the opposite axial end of the compressor.

Abstract: A check valve assembly for fluid pressure-intensifying apparatus of the double-acting type is provided. The assembly has an inner low pressure poppet valve member communicable with the high pressure chamber of fluid pressure-intensifying apparatus, and an outer high pressure poppet valve member communicable with a high pressure fluid outlet line. The check valve assembly is designed for service accessibility without having to dismantle the intensifier.

Abstract: A V-twin, two-stage compressor has valve plates disposed between the head and cylinder of each stage and mounting free-floating flexible reed intake and exhaust valves therein. The flexible reeds are movably captured between the floors of respective reed recesses, and separate, non-fixed keeper bars are disposed over, but slightly spaced from, the reeds. Keeper bars over the exhaust reed extend above the valve plate for engagement by the head. A restrictor plate lies within a valve plate recess on keeper bars over the intake valve. A cored crankshaft providing motor drive shaft lubrication, and a removable counterweight providing crankshaft use with one-piece connecting rods is disclosed. A cooling fan is driven by the removable counterweight and V-shaped fan shroud projections direct cooling air over the cylinders and heads while another cooling air port directs air over an intercooler.

Abstract: An air pump assembly including a one-piece pump stock provided with a base portion defining a first recess for receiving a rubber cushion, the pump stock being attached to an interior wall of a pump casing by securing the base portion within a second recess formed on the interior wall by opposed inwardly directed flanges.

Abstract: A piston type compressor having a cylinder block in which a plurality of compression chambers permitting a plurality of pistons to be reciprocated so as to compress a refrigerant gas pumped from a suction chamber formed in an end housing into the compression chambers through suction ports of a valve plate, openably closed by a suction valve mechanism with a plurality of suction reed valves, and to discharge the compressed refrigerant gas from the compression chambers into a discharge chamber formed in the end housing through discharge ports of the valve plate, are openably closed by a discharge valve mechanism having a plurality of discharge reed valves.

Abstract: A refrigerant gas compressor having a compression chamber in a cylinder block, a suction and a discharge chamber in a cylinder head, a suction and a discharge port provided in a valve plate for fluid communication between the compression chamber and the suction and discharge chambers in response to the opening and closing of flapper type suction and discharge valves attached to the valve plate, the suction and/or discharge valve port having a non-circular opening configuration divergently spreading from one narrow end to the opposite wide end in reverse proportion to the amount of upward movement of the suction and/or discharge valve from the face of the valve plate.

Abstract: An improved valve plate assembly for use with a reciprocating piston fluid pump such as a low capacity air compressor. A resilient rubber valve molding is positioned over a plate defining inlet and outlet ports for forming a seal between the plate and a cylinder head, for forming an inlet check valve and for forming an outlet check valve.

Abstract: A piston type compressor having a cylinder block in which a plurality of compression chambers permit a plurality of pistons to be reciprocated so as to compress a refrigerant gas pumped from a suction chamber formed in an end housing into the compression chambers through suction ports of a valve plate, openably closed by a suction valve mechanism with a plurality of suction reed valves oscillatorily movable with regard to two bearing points, respectively, and to discharge the compressed refrigerant gas from the compression chambers into a discharge chamber formed in the end housing through discharge ports of the valve plate, openably closed by a discharge valve mechanism having a plurality of discharge reed valves oscillatorily movable with regard to two bearing points, respectively.

Abstract: A pump and a stress and fatigue resistant pump head, one embodiment of which is useful for a high pressure pump and having a manifold, a valve cartridge, inlet and outlet valves in the valve cartridge, a pump fluid cylinder with a reciprocating plunger therein, a packing cartridge with packing for the plunger. The pump head may exhibit one or more of the following features: a. increased diameter packing cartridge; b. increased length front bushing; c. inclined inlet valve; d. inlet valve spring in valve cartridge on manifold side of valve; e. decreased diameter of high pressure seal of packing cartridge.

Abstract: A diaphragm-type vacuum pump device which includes a diaphragm, a pumping chamber the volume of which is changed by reciprocating motion of the diaphragm, a check valve for drawing air into the pumping chamber, a check valve for discharging air from the pumping chamber and an orifice or relief valve disposed in the pumping chamber so that the pumping chamber communicates with atmosphere.

Abstract: A high-pressure plunger pump includes a pump housing centered on an axis and including a main body having two axially spaced ends, and a pump head secured to one of the ends of the main body. A plunger coaxially extends into the pump housing and a sleeve is floatingly supported on the plunger. The sleeve has two end portions one of which is closer to the pump head than the other, converges toward the pump head and has an axial end face. An insert body is positionally secured in the pump housing at the one end portion of the sleeve and bounds a circumferentially extending annular suction channel with this one end portion. The insert body includes an annular shoulder having a substantially axially facing seating surface. Pressure and suction valves are coaxially arranged within the housing.

Abstract: A seal and retainer assembly for an air compressor piston includes a cup-shaped seal with its marginal edge extending at an angle relative to the cylinder wall, the seal having a notch extending circumferentially at the base of its marginal edge defining a hinge which allows pivoting of the marginal edge relative to the main body portion of the seal which is clamped to the piston. A head plate includes an air intake port for communicating the compression chamber with an air inlet and a discharge port for communicating the compression chamber with a compressed air discharge outlet, each of the ports having a flexible spring closure member cooperating with an inclined valve seat to allow the ports to be open whenever the compressor is shut off.

Abstract: A hermetic refrigeration compressor has a flat valve plate closing off a cylinder bore. The valve plate has an elongated recess on the outer side around the discharge port and a discharge valve assembly, comprising a flat reed valve and backing spring, fits within the recess beneath an overlying valve stop which engages the bottom of the recess at each end. The recess, the reed valve, the backing spring, and the valve stop are so configured that they can be assembled only in the correct configuration. The valve stop is held in place by an arcuate retaining spring having ends engaging notches in the valve plate and a projecting boss on a cylinder head defining a discharge valve plenum engages the retaining spring to press the spring and the valve plate into position within the recess to retain all of the parts in operating position.

Abstract: A piston-type refrigeration compressor having a more secure valve plate seal is disclosed. A cylinder housing is provided with a cylinder block having a plurality of cylinders at one end. The end surface of the cylinder block near the cylinder is coupled to a cylinder head through gaskets and a valve plate. A circular depression is formed on the end surface of the cylinder block to accommodate the gasket substantially within the depression and thereby seal the cylinder block and valve plate. In this way, the outward expansion of the gasket is prevented which prevents the gasket from deteriorating.

Abstract: A discharge valve retainer for a compressor with at least two arcuately-shaped, annular segments which segments are joined together. By joining the annular segments together, a retainer structure having a very rigid central portion results, thereby reducing stress and fatigue of the retainer. The discharge ports are arranged in an annular fashion and the suction ports are disposed radially inside the annularly arranged discharge ports.

Abstract: A swash plate type compressor having combined cylinder blocks closed, at both axial ends thereof, by front and rear housings, each having a radially inner suction chamber and an outer exhaust chamber isolated from the suction chamber, valve plates and disks interposed between the axial ends of the combined cylinder blocks and each of the front and rear housings, a plurality of long screw bolts axially and hermetically combining the cylinder blocks, the front and rear housings, and the valve plates and disks, and an internal sealing unit arranged in the radially inner suction chambers of the front and rear housings for rigidly holding the valve plates and disks against a high pressure of a refrigerant after compression, to reinforce the hermetic seal between the axial ends of the cylinder blocks and the valve plates and disks.

Abstract: A cylinder head for a piston type refrigerant compressor is disclosed. The cylinder head of the compressor is provided with an inner partition wall and an outer peripheral wall adapted to contact a gasket of the compressor such that the interior of cylinder head is divided into a suction chamber and a discharge chamber. The inner partition wall is made slightly longer than the outer wall such that upon mounting the cylinder head to the compressor the force pressing the inner partition wall against the gasket element is substantially equal to the force pressing the outer peripheral wall against the gasket element.

Abstract: A diaphragm type pump device has an elastic material imparting elasticity by the change of its volume which is placed in an operation chamber to decrease residual volume in the operation chamber when a diaphragm reaches the upper dead point.

Abstract: A suction valve for a small refrigeration compressor is in the form of a thin sheet metal reed having a sealing portion adapted to make sealing contact with a valve seat around the suction port on a valve plate. The valve reed is formed from a valve sheet by an outline defining cut so that the valve reed is integral with the sheet. The valve reed has a reduced width neck portion and in this neck portion the material is plastically deformed along a bend line so that in a normal unstressed condition the sealing portion of the reed is spaced away from the valve seat by a slight distance and as soon as the piston starts on the compression stroke the fluid pressure forces the sealing portion into sealing engagement to prevent back-flow through the suction port. When the piston starts the suction stroke, the biasing of the valve reed causes the sealing portion to move out of engagement with the valve seat before there is a substantial pressure differential across the suction valve.

Abstract: A pumped medium supplied to a suction chamber of the pump is first introduced under the action of the plunger into a working chamber of the plunger and then into a pressure chamber and a subsequent pressure line. The seats of a suction valve and of a discharge valve are arranged on a housing of a central valve, which can be inserted into a cylinder head through an opening formed in a cylinder head which can be closed by means of a base part. A piston-like element which is provided with intermediate seals between the base part and the central valve housing serves to secure the position of the central valve housing. The piston-like element is acted on at both its end faces, due to the provision of spacing chambers, by the pressure of the pumped medium in the pressure chamber. The seals are wedge-shaped so that they are increasingly urged radially outwardly against the cylinder head under axial loading.

Abstract: An intake valve apparatus for an air pump having a cylinder with a cylinder iner, a piston positioned within the cylinder liner, a cylinder head and an intake valve. The intake valve comprises an upper annular valve plate having a reed extending inwardly therein and a lower seat plate having an opening facing the reed, the valve plate and seat plate being held between mating surfaces of the cylinder liner and the cylinder head and wherein the reed is positioned for movement in the seat place.

Abstract: A diaphragm pump of the type having a housing forming a pump chamber, a diaphragm attached to an outer periphery thereof to the housing within the chamber, inlet and outlet valves communicating with the chamber, and a motor having an eccentrically rotating driveshaft, in which a connecting rod is attached to the diaphragm and includes a substantially flat portion which extends through slots formed in the housing, and an aperture which receives the drive shaft of the motor and is sized to form a slip fit therewith. The slots are shaped to slidably receive the flat portion of the rod and constrain its motion, when displaced by rotation of the drive shaft, to a single plane which is perpendicular to a rotational axis of the drive shaft, thereby eliminating the transmission of thrust and torsional loads between the rod and drive shaft so that the motor bearing life is increased.

Abstract: A pump comprises a housing member bounding an elongated cylinder bore, a piston member received in the cylinder bore for reciprocation substantially longitudinally thereof, a drive for the piston member, and a sealing arrangement between the piston member and the housing member. The sealing arrangement includes at least one sealing element having a radial supporting section and at least one lip section sealingly contacting the housing member. The wall thickness of the supporting section exceeds that of the lip section. The sealing arrangement may further include another lip section pointing in the opposite direction counter to that of the one lip section, either provided integrally on the same sealing element or separately on a discrete second sealing element assembled with the initially mentioned sealing element to form the sealing arrangement.

Abstract: Submergible pumping apparatus for use in an oil or other well comprises, in a self-contained downhole unit, a double-acting reciprocating positive displacement pump for pumping well fluid, a reservoir containing power fluid for operating the double-acting pump, a rotary motor-driven positive displacement pump for supplying power fluid under pressure from the reservoir to operate the reciprocating pump, and a control valve for properly directing high pressure power fluid from the rotary pump to the reciprocating pump and from the reciprocating pump back to the reservoir so as to provide stroke reversal of the reciprocating pump.

Abstract: A reciprocating piston compressor which is driven by a rotating camshaft and cam. An auxiliary piston is located below the compression piston. The auxiliary piston is movable by a regulated control pressure against the compression piston so that the compression piston is stopped at its top dead center position. Thus, the reciprocating piston compressor is disabled since the compression piston is no longer driven by the rotating camshaft and cam.

Abstract: A double acting hydraulically actuated pump and engine valve assembly for use downhole in a borehole for producing fossil fuel therefrom. High pressure hydraulic power fluid is forced downhole to a special control valve means located between opposed engine pistons. The valve means causes the power fluid to apply an alternating force to confronting faces of the pistons, while the opposed faces of the spaced apart pistons serve to pump and force production fluid to flow from a production zone, upward to the surface. The pump assembly can be used in combination with existing bottom hole assemblies, fixed or free type, already installed downhole in the wellbore.

Abstract: Apparatus including a reciprocating piston driven by a connecting means operating within a slider for driving a piston in a reciprocating motion. The slider is mounted in a crank case housing and includes guides for maintaining the orientation of the piston relative to surrounding cylinder walls. The cylinder is attached to the crank case housing at one end and attached to a cylinder head at the opposite end. The cylinder head includes an intake valve and an exhaust valve for controlling the flow of fluid into and from the piston chamber. To drive the piston a crank shaft is rotatably attached to a connecting means that rotates within the slider and connects thereto. Fastened to the crank shaft is a flexible coupling for coupling the crank shaft to a source of driving power.

Abstract: A diaphragm pump wherein the lower portion of an upright housing surrounds an eccentric extending into the annular lower end portion of the one-piece connecting rod the upper end portion of which extends through the central openings of two discs flanking the apertured central portion of a flexible diaphragm whose marginal portion is sealingly clamped between the main housing portion and a cover overlying the diaphragm. The top part of the upper end portion of the connecting rod is deformed to constitute a rivet head which sealingly fills the opening of at least one disc and urges the discs as well as the central portion of the diaphragm against the S-shaped surface of a carrier forming part of the connecting rod and serving to support the underside of the adjacent disc.

Abstract: A high pressure check valve for an intensifier cylinder and secured in the end of the cylinder so as to reduce the stress on the check valve due to cyclic loading.

Abstract: A piston cylinder and head arrangement for compressors including a valve plate disposed between a piston housing and the head. An intake valve, a discharge valve, and an atmospheric vent valve are all operably disposed in the valve plate, and are all arranged relative to each other and relative to an intake chamber, a compression chamber, and cooling chambers so as to necessitate only one sealing gasket for sealing said valves and said chambers from each other during certain operational phases of the compressor. The arrangement further includes a piston operable responsively to discharge pressure in excess of a certain high degree for diverting such pressure output from the pressure discharge valve to the atmospheric vent valve until such pressure drops below the certain high degree.

Abstract: In a small reciprocating pump, an annular space is provided between a cylinder and a cylinder block. The cylinder is bifurcated at its upper end, and has two projecting edges. One of these projecting edges is radially outwardly spaced apart from the other, and greater in length than the other. A cylinder head has a lower surface provided with an annular groove in which the outer projecting edge of the cylinder is engaged. A seal ring is disposed in this annular groove, and another seal ring between the projecting edges of the cylinder to maintain the cylinder in gastight contact with the cylinder head. The other seal ring also serves to support a metal plate which forms therein a valve. The cylinder head is provided with an intake passage having an intake valve, and a discharge passage having a discharge valve. The cylinder block is connected to a crank case in a gastight fashion. A crankshaft is supported rotatably in the crank case for reciprocating a piston in the cylinder.

Abstract: There is disclosed an improved compressor cylinder head fabricated out of two separate parts to reduce cost and facilitate assembly, and an improved compressor valve plate for use with said cylinder head which utilizes multiple parts to provide concentric suction and discharge passages. A novel method of fabricating the valve plate is also disclosed.

Abstract: A pump and method for moving a fluid, as blood, having a body and end members forming a cylindrical chamber. A free floating piston located in the chamber is moved along the length of the chamber with a solenoid to pump blood into and out of opposite ends of the chamber. The end members containing inlet and outlet valves and sleeves are adapted to attach to veins or tubes to carry the blood to and from the pump. When electrical power is applied to the solenoid, a magnetic force operates to move the piston in the chamber, thereby pumping blood into and out of the chamber through the valves in the opposite end members.

Abstract: A diaphragm pump is described comprising a reciprocated diaphragm for expanding and contracting a chamber communicating with a passageway connecting the housing inlet and outlet for pumping a fluid therethrough, and a pair of check valves in the passageway permitting the fluid to flow only from the inlet to the outlet. The check valves are disposed along laterally-spaced parallel axes and provide a forward fluid flow through both valves in the same direction along the laterally-spaced parallel axes, the outlet of one check valve communicating with the inlet of the other via a folded section of the passageway having two 180.degree. bends. Such an arrangement enables the diaphragm pump to be constructed in compact and/or miniaturized form.According to another described feature, the diaphragm pump is constructed in combination with the peristaltic pump having an inlet for a liquid to be pumped, and an outlet connected to the inlet of the diaphragm pump. Both pumps are driven by a common drive shaft.

Abstract: A check valve assembly adapted for connection to a high pressure reciprocating pump cylinder, comprising valve body means, inlet check valve means and outlet check valve means. The valve body means has an inlet end adapted for connection to the pump cylinder and an outlet end adapted for connection to a high pressure outlet line. The inlet end has a planar surface adapted to be exposed to the interior of the pump cylinder. The valve body means also includes a low pressure inlet passage opening in the planar surface for providing communication with a source of low pressure fluid and a high pressure outlet passage extending between the planar surface and the outlet end. Such passages are parallel to one another and spaced apart a distance at least as great as the radius of the high pressure outlet passage. The inlet check valve means is mounted entirely on the exposed planar surface in association with the inlet passage and prevents high pressure fluid backflow into the inlet passage.

Abstract: A check valve assembly for use as intake and discharge valves for pumps. The assembly includes a valve element made into a square configuration, the corners of which are slidably received in indexed relationship within radially spaced, longitudinally extending grooves formed into opposed, interior, peripheral wall surfaces of the pump housing and made complementary respective to the marginal area represented by the corners of the valve element. This configuration of the valve components prevents axial rotation of the valve element, and forms four radially spaced crescent shaped inlet and outlet passageways between each of the valve elements and the pump housing. An intake cage is axially spaced in opposed relationship respective to an exhaust cage by a valve plate, with the intake cage, exhaust cage, valve plate, intake and exhaust valve elements being concentrically arranged respective to one another.