Abstract: A pneumatic cylinder for actuating fume extraction valves in fume and heat extraction plants has a piston (2) that may be actuated from both sides with at least one working surface and that can be made to slide by pressurised air in a cylinder (1) with at least one working chamber (4), as well as an energy accumulator with regulating means. The regulating means can be controlled by control means to open or keep open the fume extraction valves. In order to obtain a compact pneumatic cylinder for a fume and heat extraction plant which is easy to install, a storage chamber in which air or pressurised air is stored as compressible pressure medium is provided as energy accumulator. The storage chamber is in communication with a compression surface (7) of the piston (2), at its side opposite to the working surface (7), so that pressure medium may flow between the storage chamber and the compression surface (7).

Abstract: A pump for impelling a fluid includes a first variable volume, the first variable volume having a first inlet for allowing the influx of the fluid into the first variable volume and a first outlet for allowing the efflux of the fluid out of the first variable volume and a first membrane defining at least a portion of the first variable volume. The pump also includes a first contractile actuator, for displacing the first membrane from a first position to a second position in such a manner as to vary the first variable volume and a second contractile actuator, for restoring the first membrane from the second position to the first position in such a manner as to vary the first variable volume. A first check valve is coupled to the first inlet for regulating the influx of fluid into the first variable volume through the first inlet and a second check valve is coupled to the first outlet for regulating the efflux of the fluid out of the first variable volume through the first outlet.

Abstract: The dual stage, dual mode air pump is selectively operable in a low pressure, high volume mode or a high pressure, low volume mode. It includes a pump head, an outer tube that is engaged to the pump head, an inner tube that is engaged to the pump head and a middle tube that is slidably engaged to both the outer tube and the inner tube. A mode pump switch is utilized to allow the pump operator to change the mode of the pump. In the preferred embodiment, the mode switch is disposed within the pump head. It includes an air passageway having a manually switchable valve disposed therein. In the high volume, low pressure mode the valve switch is closed, whereupon pumped air passes into a pneumatic article engaged to the end of the pump. When the valve switch is opened, the pump is operable in the low volume high pressure mode, and a portion of the pumped air is outletted into the ambient environment, rather than being pumped into the pneumatic article.

Abstract: The invention concerns an artificial heart driving device having at least one blood chamber which is disposed in a pump housing and draws in and expels blood cyclically by means of a plurality of pressure plates which can be driven by a motor. The motor is directly connected to a drive gear or cam component. A movement component actuating the plurality of pressure plates engages with the drive gear or cam component and performs a reciprocating movement as the drive gear or cam component rotates.

Abstract: A positive displacement inductive pump which includes a pair of steel cylinders or sleeves having a non-magnetic corrosion resistant inner surface and non-magnetic alloy rings disposed at each cylinder end. Three ferromagnetic pole pieces having an axial opening are provided with each cylinder disposed between a respective pair of the pole pieces and connected to the pole pieces with the alloy rings. A pair of oppositely disposed steel plates connected to the pole pieces forms a magnetically conductive circuit between the pole pieces. A piston positioned within the bore defining a displacement chamber adjacent to each end of the bore. The piston includes a rod formed of magnetic material with a corrosion resistant lining encapsulating the rod. The pistons outer lining surface forms a seal with the material on the inner surface of the cylinders.

Abstract: The present invention is directed to a system for direct injection of chemicals or other additives in a liquid solution into a spray nozzle. The injection system of the present invention may be mounted adjacent, or in close proximity, to the spray nozzles of a sprayer. The present invention comprises a variable speed/stroke diaphragm pump capable of providing a double pumping action such that a liquid solution may be continuously pumped at a controllable rate to one or more spray nozzles of a sprayer.

Abstract: Replace the abstract in the instant application with the following abstract: A compressor has a reciprocating piston operating in a working area to compress the working medium, a drive unit for the reciprocating movement of the piston, and an intake and discharge device for supplying and expelling the working medium. The liner, in which the piston reciprocates, is manufactured as one piece with a valve plate. Further, the slider crank mechanism used to drive the piston is provided as a drive unit. As a result, the size of the compressor can be substantially reduced, virtually vibration-free motion is achieved, and the compressor reliability is appreciably enhanced.

Abstract: The invention is a method for producing reservoir fluids from an underground reservoir through the wellbore. The method includes the steps of intaking the gas phase from the wellbore into the wellbore-contained pump drive, powering the pump drive using the gas pressure of the gas phase in the wellbore, pumping the liquid phase from the wellbore towards the surface by a first pump and exhausting the gas phase from the pump drive towards the surface.

Abstract: An ion selective electrode assembly is provided having a sample injection cup, a flow cell analyzer and multiple module pump for simultaneously pumping liquids between the sample injection cup and the flow cell analyzer using a single motor. One of the pump modules is capable of pumping a reference solution directly to the flow cell analyzer. Flow through each pumping module is controlled by a pair of rocker valves. The sample injection cup includes a first diaphragm valve for allowing a mixture of sample and reagent to flow to the flow cell analyzer. The sample injection cup further includes a second diaphragm valve installed immediately downstream of the first diaphragm for allowing a flushing solution to flow throughout the sample injection cup and the flow cell analyzer.

Abstract: The present invention relates to an oil pump of the forced lubrication system in an automobile engine. The oil pump is mounted in the lower crank case, preferably at the bottom of the oil pan in order to be immersed in a lubricating oil filled therein. The oil pump of the present invention is a combination of the well known plunger type oil pump and the swash-plate pump, which has two pistons and one T-shaped operating rod incorporated therein. The outer end of the T-shaped operating rod is extended to the engine crank shaft. The outer end of the operating rod is directly coupled to the bearing load of the crank shaft, opposite to the engine connecting rod, to form a second connecting rod which allows translation of the connecting rod from rotation of the crank shaft.

Abstract: A reciprocating machine converts linear motion to rotary motion or vice-versa and is associated with a supply of working fluid, and includes rotational power apparatus having a rotational motion transfer member; a cylinder defining a longitudinal axis and having a first end at which are located working fluid input and output apparatus, and further having a second end; a piston located within the cylinder and arranged for linear, reciprocating travel along the longitudinal axis between the first and second ends; a connecting rod having a first end connected to the piston, and further having a second end portion; and linkage apparatus.

Abstract: A hollow through-bolt is threaded internally and externally, at one end, to receive therein a reciprocable, end-threaded rod. A pair of fluid-control valves, centrally bored, are mounted on the through-bolt in spaced apart disposition. The other end of the through-bolt has a shoulder formed thereon for seating one of the valves thereagainst, and the other valve central bore is tapped for threaded engagement with the one end of the through-bolt. A sleeve, slidably engaged with the through-bolt, and interposed between the valves, maintains the one valve positioned against the shoulder.

Abstract: The invention comprises an improved pressure transfer module having, in one embodiment, two double-diaphragm pumps each having its diaphragms connected to one another by a respective drive shaft for reciprocating motion. Spool valve assemblies are mounted directly on the connecting shafts of each pump and arranged to maintain the operation of the two diaphragms of the pumps 90.degree. out of phase in that each such assembly constitutes pressurized water control valves for the other pump. The two pumps are mounted with the drive shafts at 90.degree. to one another, and arranged to pump in sequence so that a complete pumping cycle comprises four pumping strokes, one every 90.degree.. To insure reversal of motion of the shafts in proper phase, the invention includes either two, meshed square cams and cam surfaces formed on respective shafts connecting the pumping surfaces, or a floating crankshaft with each end pivoted in one of the connecting shafts.

Abstract: A hand pump includes a piston slidably engaged in a housing for separating the housing into two chambers. A tube is secured on top of the housing. The piston includes two annular grooves for receiving two sealing rings. A piston rod has one end secured to the piston and has the other end extended outward of the housing. The piston may pump the air in upper chamber into the tube when the piston moves upward, and the air in the lower chamber may be pumped into the tube when the piston moves downward. The tube includes two mouths for engaging with different tire valves.

Abstract: A compressor which provides for minimum clearance in the compression chamber while substantially reducing the heat normally experienced by the piston during the compression stroke of a compressor of this type. The suction valve(s) of the compressor is concentrically mounted in the piston while the discharge valve(s) is concentrically mounted in a stationary position within the cylinder. Since the high heat of compression occurs at the discharge valve, the piston will be much cooler than in prior art compressors of this type which improves the efficiency of the compressor and which substantially extends the operational life of the piston rings.

Abstract: The invention relates to a double diaphragm pump having flexible diaphragms disposed in displacement spaces and connected and mechanically coupled to piston rods, the displacement spaces being communicated via check valves to a suction manifold on the one hand and to a pressure manifold on the other hand, wherein each diaphragm is connected to a piston rod, which piston rods extend coaxially and are mounted on opposite sides to a guide frame having at least one lineal guide for a guide block which rotatably mounts a crank pin of a crankshaft.

Abstract: A device (10), and a method for forming such a device (10), for a fluid system for a vehicle, comprises first and second members (12, 13). The first member (12) is adapted for direct mounting on the chassis or engine of a vehicle (11); the second member (13) defines at least part of a leak tight fluid chamber (15) of the device (10). The first member (12) is of a thermoset material suitable for withstanding operating conditions and loads associated with direct mounting of the device (10) on the chassis or engine (11), and the second member (13) is of a thermoplastic material suitable for welding to ensure leaktightness of a fluid chamber (15). The second member (13) is interlocked with the first member (12) during moulding thereof.

Abstract: An object of the present invention is to provide a pump which suppresses a decrease in the volumetric efficiency of the pump to a great extent even in case that the kinematic viscosity of a fluid is high with a compact structure of the pump itself.

Abstract: A pump has an extruded metal housing surrounding a square internal chamber accommodating a piston assembly with square pistons. An eccentric member and block assembly associated with a driven shaft reciprocates the piston assembly to pump fluid. The flow of fluid into and out of the pumping chamber is controlled with intake and exhaust valves incorporated into plates mounted on opposite ends of the housing.

Abstract: A hand pump includes a housing having two chambers communicated with each other. An attachment member is secured to the front portion of the housing. A piston is slidably engaged in one of the chambers and includes two annular grooves for receiving two sealing rings. A piston rod has one end secured to the piston and has the other end extended outward of the housing. The piston may pump the air in front of the piston into the attachment member when the piston moves forward, and the air in the rear portion of the piston may be pumped into the attachment member via the other chamber.

Abstract: A connecting rod used for a multiple chamber compressor pump comprises a central section having in the main surface thereof an opening for receiving therein a bearing for an eccentric of the multiple compressor pump, at least two pushing sections, and respective hinge areas arranged between the central section and the pushing sections and generating restoring forces, when the pushing sections are deflected relative to the central area.

Abstract: A system for improving the economics of production by reducing lifting costs of a producing well utilizes the upstroke of a pump to produce a fluid mixture of primarily oil with only a fraction of the produced water and the downstroke to inject the remaining produced water beneath a packer into a lower formation.

Abstract: A reciprocating pump particularly useful in ventilator apparatus includes a piston reciprocatable axially within a cylinder and dividing its interior into an inlet chamber and an outlet chamber, a wall fixed within the inlet chamber, and a drive housing fixed to the wall. The drive housing includes a motor, a rotor rotatable by the motor, a nut rotatable within the drive housing, and a screw threadedly coupled at one end to the nut and fixed at its opposite end to the piston. The piston is substantially unrestrained for axial and rotary movement such that forward and reverse rotation of the nut by the motor reciprocates the screw and the piston axially of the cylinder, and also permits the screw and the piston to rotate with respect to the cylinder to thereby even out wear between the piston and cylinder.

Abstract: A fluid intensifier (10) includes an unequal-area pump piston (11) and a drive piston (14). The large-area pump piston chamber (21) communicates with the small-area pump piston chamber (29) via a communicating conduit (30) having a check valve (25) therein. The pump piston is coupled to a drive piston (14) having a lost-motion connection (18) with a two-lobed pilot valve spool (41). The pilot valve (16) controls a pilot pressure in the spool end chamber (60) of a spring-biased control valve (19). The fluid intensifier is automatically reversing as the pump piston approaches either end of its stroke, and is arranged to provide a substantially-constant intensified fluid pressure (P.sub.i) at an outlet.

Abstract: A high pressure fluid pumping transformer apparatus has a cylindrical transformer body surrounded by an outer pressure sleeve defining an annular working fluid chamber substantially surrounding the transformer body which receives fluid from an external source. The interior of the transformer body is divided into a central exhaust chamber and axially spaced working chambers at each end thereof. High pressure cylinders mounted in the transformer body at the end of each working chamber have a high pressure chamber spaced axially outward of the working chambers which contains a suction valve. Discharge valves mounted in the outer ends of the transformer body each contain a discharge valve and discharge port. An exhaust outlet extends from the exhaust chamber and is isolated from the working fluid chamber. A plunger reciprocally mounted in the transformer body has a portion which reciprocates in the working chambers and a reduced diameter at each end which reciprocates in the high pressure chambers.

Abstract: A double acting piston blood pump having distal and proximal manifolds that are connected by a cylinder having a piston reciprocating therein and dividing the cylinder into a proximal and distal chambers. The manifolds have chambers that are in fluid communication with the distal and proximal chambers of the cylinder and one way valves for controlling fluid flow from and to the cylinder chambers.

Abstract: A rotary motion/constant velocity linear reciprocating motion conversion device capable of converting rotary motion into a constant velocity linear motion or vice versa, and a hydraulic system which can minimize a ripple by using the above-mentioned conversion device, comprises a rotary motion part having a pair of first power transmission elements rotating at the same speed mounted to a common shaft, each element having alternatively positioned teeth capable of transmitting power. A linear motion conversion part comprises a second pair of power transmission elements each positioned adjacent to and engaging the teeth of the first elements. The second elements are each slidably mounted to a helical spline and comprise projections that engage helix grooves arranged in opposite directions along the shaft. The interaction of first and second power elements causes the linear motion of the helix shaft. The helical spline comprises a piston at each end that reciprocates within a respective cylinder.

Abstract: A reciprocating piston fluid pump according to the present invention comprising: a pump driving section including a cam operated by an engine and a roller driven by the cam, the roller being provided at a lower end of a piston rod; a piston provided at an upper portion of the piston rod; a pump chamber housing the piston and divided into a piston upper chamber and a piston lower chamber by the piston, the pump chamber including a bearing opening at a central portion of the piston lower chamber, through which the piston rod extends; a rod seal retainer portion provided between the piston rod and the bearing opening of the pump chamber; a spring for urging the piston rod downwardly; oil passage means for communicating the pump upper chamber or the pump lower chamber with the bearing opening, the oil passage means being provided on an oil seal member or the piston rod; oil supply means for supplying lubricating oil to the pump driving section or the bearing opening; and at least one communication hole provided b

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

Abstract: A fluid transport device for compressing or pumping a work fluid comprises a rotating coupling having an off-center first gear, a fixed internal second gear of twice the pitch diameter of the first gear, and a housing having a diametrical channel with a sliding piston disposed therein. A crank-like connector rotatably coupled with the first gear has a depending lug engaged within a hole in the piston and acts to drive the piston to and fro within the channel. First and second chambers are defined to either side of the piston, with the terminal ends of the chambers defined by the wall of the housing each having an egress aperture and an ingress chamber. A slotted depending rim of the coupling alternately obturates the egress aperture of one chamber and the ingress aperture of the other in step with the intake and expulsion stroke of the piston in each chamber.

Abstract: A pumping unit, particularly for waterblasters and similar equipments, comprising the pump, the control unit, and the pressure damping device to form a single body, although they can be separated from each other. The pump has one double-acting plunger.

Abstract: The present invention relates to a shock absorber pump/compressor which comprises attachments to the car's chassis and to the wheel axle housing; a rack gear that is set into a reciprocating motion as the car runs on the uneven surface of the road; a pinion gear that is rotated back and forth by the rack gear; a crank that is attached fixedly to the shaft of the pinion gear and which sets a double piston to move in a reciprocating manner. A diaphragm is attached to each piston head and the periphery of each diaphragm is clamped tightly between the cylinder and a cylinder head. The interior of each cylinder head and a diaphragm form a contractive and expansive space which draws in fluid from an outside source as the space expands and forces the fluid out as the space contracts. At the same time as fluid is drawn into one contractive/expansive space, fluid is forced out of the other space at the other end of the double piston.

Abstract: A motor compressor unit comprises a hermetically sealed housing, a vibration motor with a rotationally vibrating drive shaft, and a symmetrical twin free-piston compressor comprising two oppositely disposed identical free pistons which can be reciprocated in respective cylinders by the drive shaft. In order to minimize piston drift from the center position, each cylinder is formed with a duct connecting the respective compression space to the space between the housing and the motor-compressor where the suction pressure prevails, which ducts are situated at equal distances from the respective cylinder end walls and can be closed by the respective pistons. As a result of this, the pressure in both cylinders is built up with the same swept volume and piston drift is minimized.

Abstract: A double acting simplex plunger pump comprising a pair of unique unitary combined stuffing box and head members pre-assembled with a double ended plunger, the subassembly being sandwiched between the axial end face of a drive motor and a flat surface of a unitary manifold means and further characterized by means including check valve means for aligning and holding the members.

Abstract: A double acting simplex plunger pump comprising a pair of unique unitary combined stuffing box and head members pre-assembled with a double ended plunger, the subassembly being sandwiched between the axial end face of a drive motor and a flat surface of a unitary manifold means.

Abstract: The compressor has a straight cylinder wholly confined within which are inlet valves, and reciprocatable discharge valves. One inlet valve is set in place by a centerbolt which can be turned by a wrench (or the like) to move the inlet valve to selected positions relative to its confronting discharge valve, whereby the volume of the clearance pocket is varied. The centerbolt mounted inlet valve, then, comprises an instrument for selectively varying the clearance pocket volume, obviating any need for any special clearance pocket varying devices or components.

Abstract: A pumping apparatus comprises a piston/cylinder assembly mounted between two laterally spaced end cap sections attached to base means and including spring-loaded valve devices. A piston rod is movably supported in and extends outwardly from one of the end cap sections. A manually operated linkage mechanism effects axial longitudinal movement of the piston rod and a support mechanism maintains longitudinal axial alignment of the piston rod during its longitudinal axial movement. The longitudinal movement of the piston rod operates in concert with the spring-loaded valve devices to pump fluid manually when the pumping apparatus is positioned in any angular disposition with respect to the horizontal.

Abstract: A positive displacement apparatus of the general type used as superchargers on internal combustion engines has two or more compression chambers capable of lateral movement to accommodate circular motion of the pistons. The driving forces for the chambers are derived from forces originating independently of the movement of the pistons, that is, the chambers, instead of being driven by the pistons, are driven directly from the eccentric mechanism that drives the pistons. A lateral reciprocating motion is imparted to two transfer members that are mechanically secured to the end of, or form part of, the chamber. Preferably, each of the end plates of the chamber forms an integral part of the chamber drive structure. An orbitally-driven, non-rotating, rigid drive sleeve encompasses two spaced eccentric drive members on a drive shaft and supports the piston drive structures. Rotational forces generated by the chamber drive arrangement are resisted by sets of guides rails and slidably mounted pads.

Abstract: A compressor shielded from crankcase oil by a wall having a hole surrounded by a wiper through which a piston rod assembly passes and having the chamber between the crankcase and the underside of the piston provided with a pressure relief valve and an atmosphere vent having a check valve whereby the chamber is never at sub-atmospheric pressure and there is never gas flow through the wiper toward the piston.

Abstract: A radial piston pump for a brake system in automotive vehicles. The resulting system produces little noise and is split up into various circuits. The resulting system provides damping of the pressure vibrations caused by the pump pistons. The individual channels are furnished with permanently allocated damping chambers. These damping chambers are combined with the associated outlet valves to form a replaceable construction unit (damping-chamber valve) which is adapted to a given application.

Abstract: An improved double acting piston pump of the type having a shaft connected to the piston for reciprocating the piston wherein the shaft extends from the pump body. The improvement of the present invention is to reciprocate the shaft with an asymmetrical uniform motion rotary cam so that the pump delivers the same constant flow rate of a liquid being pumped during both the forward and the backward movements of the pump's piston.

Abstract: A reciprocating pump mechanism having a pump body forming a fluid inlet chamber and opposed pump cavities in communication with the fluid inlet chamber. The pump employs a piston having opposed pumping extremities adapted for pumping entry into the respective pumping cavities and is of a length such that with one pumping extremity positioned to its full extent within a pumping cavity the opposite pumping extremity there of is disposed in fluid inletting relation with the opposite pumping cavity. The piston may also include opposed drive shafts at least one of which extends from the pump body. One of the piston shafts may be adapted to be driven by any suitable reciprocating prime mover while the opposite piston shaft is adapted for connection to a similar exposed piston drive shaft of a similar double-acting piston pump to thereby provide for connection of the pumps in tandem driven relation by a single prime mover.

Abstract: The assembly, designed for use in combination with a straight-cylinder, gas-compression chamber, has a center bolt which is threaded at opposite ends thereof to receive a pair of valve sets. Each of the latter has a ported valve seat, valve guard, and ported valve plate. The guard is set about the bolt, and against a shoulder formed on the bolt therefor. The seat is centrally threaded, to engage one of the threaded ends of the bolt, and it and the guard confine the valve plate therebetween. In that one of the valve sets is turned 180.degree. from the other, i.e., the two guards being in confrontation, and the two seats remotely disposed, vis-a-vis, the one valve set is open to fluid flow, while the other is closed, as the assembly is reciprocated in such a straight-cylinder, chamber. Identical valve sets, on different, short bolts set in end closures of such a chamber, serve as gas inlet valves, while the reciprocable assembly carries the discharge valves.

Abstract: A hydraulic pump provides two different fluid pressure outputs from a single input. The pump includes a first double acting piston and cylinder having a pair of inlets on opposite sides of the first piston and a pair of outlets on the opposite sides of the first piston. A second double acting piston and cylinder are provided which cylinder has a pair of inlets on opposite sides of the second piston and a pair of outlets on opposite sides of the second piston. A common piston rod interconnects the pistons and means is provided for alternately supplying fluid to the first inlets of the first and second cylinders on one side of the pistons and then to the first inlets on the other side of the first and second pistons to cause the first and second pistons to reciprocate within the first and second cylinders, respectively.

Abstract: A double acting simplex plunger pump comprising six unitary extruded members, i.e., a crankcase body, a manifold connected thereto and, at each end of the body a stuffing box member abutted on one face to the body and, on the opposite face, to a head member. The pump also comprises a double ended plunger supported by the body for reciprocation of the ends thereof into pump recesses of the stuffing box members.

Abstract: A rotatably driven positive displacement pump including a tubular conduit with a barrel communicating therewith, the barrel having a plurality of pairs of spaced apart fluid inlet and fluid outlet ports, each port being controlled by a unidirectional valve, a piston reciprocally supported within the barrel between each pair of inlet and outlet ports, each piston being tubular and having a continuous substantially sinusoidal wave-shaped groove in the interior surface and a groove in the exterior surface in a plane of the piston cylindrical axis, a pin extending from the side wall for each piston and into the exterior groove to permit axial displacement, but limiting the rotation of the piston, a drive shaft rotatably received within the barrel and within each piston opening and a crank member affixed to the drive shaft for each piston and extending within the wave-shaped groove in the internal surface of the piston so that as the crank shaft is rotated, the pistons are axially displaced within the barrel and a

Abstract: To reduce space requirements, vibrations and certain stresses in a motion converting mechanism, a rod is constrained to reciprocate within a housing where the rod is attached to the crankshaft by a cylindrical shaped connector that orbits around the crankpin in a direction opposite that of the crankshaft while rotating inside the rod. Through the center portion of each stroke, the connector also interfaces directly with the housing by such means as a cam cam-follower or gearing to eliminate a second degree of freedom at midstroke. The resulting motion defined for the center of the connector and the rod is sinusoidal being twice that of the motion of the crankpin in the axis of reciprocation. The resulting stroke is four times the crankpin offset.

Abstract: An electrically driven double-acting diaphragm air pump having a diaphragm-driven system including an eccentric for the motor shaft, a freely movable yoke having a solid framework solely supported by the diaphragm system with one end connected to a first diaphragm assembly, and at an opposite end to a second diaphragm assembly, and with the yoke having a large central opening. The eccentric is coupled directly to the solid framework through a yoke driver. The yoke driver is rotatably connected to the solid framework at one end of the framework adjacent to the first diaphragm assembly, and is coupled to the eccentric through ball bearings, with the opposite end of the yoke driver suspended for free movement within the large central opening of the solid yoke framework.

Abstract: An infusion pump for administering fluid from a fluid source to a patient comprises a base member having an electric motor for driving a fluid pump housed within a cassette detachably mountable on the base and connectable to the motor. The cassette houses a reciprocative piston and cylinder assembly which both pumps fluid to the patient while simultaneously drawing fluid from the fluid source so as to maintain a continuous flow rate of fluid to the patient. The cassette also houses deformably closable pairs of tubes connecting each of the pump's two fluid chambers to the cassette inlet and outlet respectively to provide the necessary valving to produce continuous flow in cooperation with the reciprocative piston and cylinder assembly.

Abstract: A scotch yoke compressor assembly is disclosed wherein four radially disposed pistons reciprocate in cylinders defined in a crankcase. In a central portion of the crankcase, a scotch yoke mechanism operably couples the pistons to an eccentric portion on a rotating crankshaft. Each piston includes suction ports extending therethrough and a suction valve on the piston head. The suction valve is operably retained on a piston head and the piston is attached to a yoke member by a single bolt. The bolt head is received within a recess coined in a valve plate interposed between the crankcase and a cylinder head cover. Circularly arranged discharge ports in the valve plate are opened and closed by an annular discharge valve guidedly retained against the valve plate at diametrically opposed locations, by a combination of guide pins and an annular retainer member.