Abstract: A fluid dispensing system is provided which has first diaphragm pump means, a filter connected to receive the discharge of said first pump, and accumulator/second diaphragm pump means connected to receive the discharge of said filter. Hydraulic fluids pumped by cylinder/piston/stepper assemblies independently actuate each of the diaphragm pumps, providing accurate, controllable and repeatable dispense of the subject fluid.

Abstract: An improved dual-stage pump system is provided for the accurate pumping and filtering of viscous fluids. Two hydraulically activated pumps are provided in series with a filter and reservoir disposed in-line between the two pumps. The reservoir acts as a source bottle for the second pump and allows the first pump to pump the viscous fluid through the filter at a rate independent of the dispensing rate of the second pump. By operating the first pump at a rate independent of the second pump, back pressure at the filter is avoided. Each hydraulically activated diaphragm pump is equipped with an improved diaphragm that is pre-formed to the geometries of the process fluid cavity thereby eliminating any inaccuracies in the operation of the pumps due to expansion of retraction of the diaphragm during pump operation.

Abstract: An apparatus is provided for transferring electrically conductive coating materials, such as water-based paint, from a source to at least one coating dispenser such as a spray gun for discharge onto a substrate. In alternative embodiments, the coating material is supplied to the dispenser(s) from parallel flow paths which are comparatively simple and inexpensive in construction, and which are capable of delivering high pressure, high volume flows of coating material while substantially eliminating pressure fluctuations in the coating material supply when switching from one flow path to another.

Abstract: A fluid dispensing system is provided which has first diaphragm pump means, a filter connected to receive the discharge of said first pump, and accumulator/second diaphragm pump means connected to receive the discharge of said filter. Hydraulic fluids pumped by cylinder/piston/stepper assemblies independently actuate each of the diaphragm pumps, providing accurate, controllable and repeatable dispense of the subject fluid.

Abstract: An improved dual-stage pump system is provided for the accurate pumping and filtering of viscous fluids. Two hydraulically activated pumps are provided in series with a filter and reservoir disposed in-line between the two pumps. The reservoir acts as a source bottle for the second pump and allows the first pump to pump the viscous fluid through the filter at a rate independent of the dispensing rate of the second pump. By operating the first pump at a rate independent of the second pump, back pressure at the filter is avoided. Each hydraulically activated diaphragm pump is equipped with an improved diaphragm that is pre-formed to the geometries of the process fluid cavity thereby eliminating any inaccuracies in the operation of the pumps due to expansion of retraction of the diaphragm during pump operation.

Abstract: A pulsatile pump the output of which is infinitely variable between a slow pulsatile flow and increased up to a sharply pulsed flow rate until the pulses run together and a smooth flow results, and which may be varied between wide output pressure and frequency limits. The pump is comprised of a pneumatic control circuit, at least two pneumatically isolated compression chambers, and a novel inlet/outlet pump cartridge and condition-responsive locking means. Operation of the pump is controlled by the use of novel tactile pneumatic response switches. Each compression chamber is communicated with a supply of working fluid through the cartridge. Means are provided for varying the operation of the pneumatic circuit and hence the pump. A flow of pressurized fluid, such as air or nitrogen, is used as the operating media of the pneumatic circuit, although other fluids may be used. Means for monitoring and adjusting pump system parameters are also provided.

Abstract: A compact redundant cooling module has four fans operated by two electric motors, one electric motor serving to operate two fans at one time to cool a heavy industrial engine as required for efficient operation; the other motor and pair of fans being rotated but not operated, in order to provide a backup system.

Abstract: The invention relates to a pump assembly comprising first and second pump units designed to be driven hydraulically, consisting of pump housing chambers, pump housing cylinders with pumping plungers mounted therein, and hydraulic cylinders with driving chambers which can be connected to a pressure source through a control valve for developing in the driving chambers a certain hydraulic pressure, which is used to operate the driving plungers.

Abstract: A pair of control valve assemblies for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve assembly is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow. Each of the valve assemblies uses an intake-exhaust valve and a signal valve with the signal valve of one pump being connected to be pressure responsive to the piston of the opposite cylinder or pump.

Abstract: A multiple well pump assembly tool. The tool is designed to allow use of multiple submersible pumps in a single borehole. The tool collects the output from two or more pumps and discharges the combined output into the well discharge line. The tool may be utilized for efficiently controlling pump output to meet varying load demands, or alternatively for incrementally increasing output from a deep well. The tool may also be used to provide a primary and a standby pump in a single well bore. The rugged tool assembly is advantageous for pumping deep wells of relatively small diameter where high output is required. In one embodiment, a first header gathers output from a lower pump, and a second header combines that output with the output from a second pump and sends the total output to the well discharge pipe.

Abstract: An improved water pressurizer comprises a pair of piston and plunger type intensifiers each driven by pressurized oil on one side of the piston and returned to the starting position by air pressure on the opposite side of the piston. Magnetic sensing switches detect proximity of the piston as it nears the end of a power or return stroke and send enabling signals to electropneumatic relays controlling air actuated ball valves on input and output oil lines. Because of the displacement volume and piston to plunger ratio, the intensifiers reciprocate at unusually low frequencies, reducing down time for maintenance or repair and thereby increasing reliability and capacity factor. Installed on a trailer for transportation, the apparatus can be attached to any available water supply for providing pressurized working fluid to a remote site.

Abstract: A fluid pumping system that maintains the temperature rise at a minimum value of the fluid being recirculated in the pumps during a given operating condition in the pumping system's operating envelope be disclosed. A pair of positive displacement pumps judiciously sized at different capacities are driven by a differential pumping or gearing system that is driven by a single source and cooperates with a fluid circuit delivering flow to a receiver so that the relationship of the pressure in the fluid circuit bears a given relationship to the flow capacity produced by each pump at given operating points in the operating envelope.

Abstract: A control valve assembly for alternately actuating a pair of fluid-driven free-piston devices by using fluid pressure communication therebetween. Each control valve is switched by a pressure signal depending on the state of its counterpart's piston. The communication logic is arranged to provide overlap of the forward strokes of the pistons, so that at least one of the pair will always be pressurized. Thus, uninterrupted pumping of liquid is made possible from a pair of free-piston pumps. In addition, the speed and frequency of piston stroking is entirely dependent on the mechanical power load applied. In the case of a pair of pumps, this enables liquid delivery at a substantially constant pressure over the full range of flow rates, from zero to maximum flow.

Abstract: A vertical centrifugal hydraulic pump assembly is provided fitted with at least one replaceable pack incorporating the centrifugal hydraulic elements of the pump, the pack being clamped between two flanged end plates and mounted vertically in a receiving bore of a pump body, the base region of the receiving bore housing a flat annular non-return valve fitted between the inner wall of the bore and the outer wall of a central inlet connector, the valve opening in the direction of delivery of the pump.

Abstract: A fluid dispensing system is provided which has first diaphragm pump means, a filter connected to receive the discharge of the first pump, and second diaphragm pump means connected to the receive the discharge of said filter. Hydraulic fluids pumped by cylinder/piston/stepper assemblies independently actuate each of the diaphragm pumps, providing accurate, controllable and repeatable dispense of the subject fluid. In addition, pressure sensing means are provided to indicate the pressure of the actuating hydraulic fluids, and computer controller means may be utilized to monitor, adjust and control the rates and intervals of filtering and dispense of the system in response to said pressure sensing means or otherwise.

Abstract: A multistage turbocompressor with a two-stage transmission with a double intermediate cogwheel (5) consisting of two cogwheels (51 and 52). The first cogwheel has a larger module than the second cogwheel and engages only a central cogwheel (2) that drives the pinion shafts (3 & 4) in the first stage. The second cogwheel engages only the pinion shafts (6, 7, & 8) in the second stage.

Abstract: A dual pump fault tolerant fuel delivery system for providing a metered fuel flow to an aircraft gas turbine engine, combines a fixed displacement pump with a demand control pump operating at a speed commanded by an electronic engine control such that the electronic engine control can provide the metered fuel flow by controlling the speed of the demand control pump and the area of a metering valve to reduce the temperature of the fuel in comparison to fuel systems employing a fixed displacement pump, a pressure regulating valve and a bypass fuel flow system.

Abstract: A scroll compressor apparatus comprising a closed scroll compressor, an oil reservoir vessel separate from the closed scroll compressor, a discharge pipe, and an oil supply pipe. The closed scroll compressor includes a closed container having a suction port through which a compression medium is suctioned, a scroll compression mechanism encased in the closed container, a motor encased in the closed container, a first oil supply passage extending through an end plate of a fixed scroll and through which a first opening facing a sliding contact portion with an orbiting scroll is communicated with an oil supply port, a second oil supply passage formed in an end plate of the orbiting scroll and through which the first opening is communicated with a second opening facing an end face of a driving shaft, and a third oil supply passage, formed in the driving shaft, through which the second opening is communicated with the third opening facing a bearing supporting the driving shaft.

Abstract: The invention refers to a multiple connection of rotation vacuum pumps having a common housing and drive motor. The vacuum pumps arranged in two rows. Each one of the vacuum pumps has a pump gear, and these gears, together with a drive gear, are arranged such that they form a single row with their teeth drivingly intermeshed. Preferably only inner parts of the pump are located in the housing.

Abstract: A dual capacity pump having at least two gear pump stages with a common fluid inlet passage, each pump stage having a discharge port, the discharge port for one stage communicating with a fluid pressure load through a flow delivery passage and the discharge port for the other stage communicating with the flow delivery passage through a one-way flow valve, and flow control valve means responsive to an operating variable for connecting the discharge side of the other stage to the common fluid inlet passage during operation in a first operating range of low driving speeds for the pump and to said flow delivery passage through the one-way flow valve during operation in a calibrated range of values for the operating variable.

Abstract: A system for metering the volume of a liquid, e.g. ink, supplied by a positive displacement pump to an installation, such as a printing press, employs a device for generating a first series of signals each indicative of completion of a pumping stroke. The speed of the pump is also sensed to generate a second series of signals each indicative of the positive supply of liquid by the pump. The signals of the first series are counted only in the presence of a corresponding signal of the second series. The result is an accurate numerical indication of the total volume of liquid pumped.

Abstract: A valveless, positive displacement pump including a living hinge for angularly adjusting a pumping head with respect to a rotatable drive member is provided. The pump includes a block to which a pumping head and drive member are mounted. The block includes a first support pivotably connected to a second support by means of an integral, flexible hinge. The pumping head is mounted to the first support while the rotatable drive member is mounted to the second support. Movement of the first support about the flexible hinge allows the stroke of the piston, and therefore the flow rate of the pump, to be adjusted. Such a pump may be manufactured by extruding the block in elongate form and then cutting it into individual sections to which pumping heads may be mounted.

Abstract: An hydraulic power generating pack 1 comprises a primary pump 23 of the multi-cylinder, reciprocating ram type with a reciprocable piston 27 located in each cylinder 28 and displaceable by a crank shaft 20 rotatable by a prime mover 2 to provide a primary hydraulic fluid output 32 at a predetermined constant pressure and constant volume, and a power take off 14 to drive a secondary pump 36 of the pressure compensated variable delivery type, the output 40 of which drives a pressure intensifier 42 serving to intensify, to the required secondary pressure and volume, hydraulic fluid supplied to the intensifier 42 at a first pressure and volume.

Abstract: A system of parallel compressors for compressing fluids miscible with oil. Means are provided for internally separating each compressor connected in parallel into a discharge chamber, a suction chamber, and a crankcase chamber, the chambers of each compressor being independent of one another. The crankcase chambers are connected in oil and gas flow communication with one another. A suction manifold is connected to the suction chambers, and each crankcase chamber is equalized with suction pressure. A discharge manifold is connected to the discharge chambers. Means for separating the oil from compressed fluids leaving the discharge chambers and returning the oil so separated to the crankcase chambers are also provided.

Abstract: A pump assembly including a primary power source and several axial piston pumps is disclosed. A connection flange is provided on the primary power source on which a first axial piston pump is connected. At least one more axial piston pump is coaxially connected on the connection flange. In order to support the multipump assembly stress-free and pinch-free without special adjustments, it is proposed to fasten at least approximately vertical guide or support plates on at least one and preferably both sides of the first axial piston pump at the connection flange of the primary power source and to connect the plates through an intermediate flange housing with the additional axial piston pump that is connected coaxially with the first axial piston pump.

Abstract: A high volume, low pressure impeller apparatus is provided for the spraying of liquids having a wide range of viscosities. The use of two serially interconnected impeller blowers enables the spraying of both stains and latex paints while still achieving fine sprayed coatings.

Abstract: A multiple channel medication infusion system is disclosed which has a plurality of disposable pump cassettes mounted on a single main pump unit, thereby making the system compact and resulting in an economic system. The system has a printer which may be connected to the main pump unit to provide a printed record of system operation. Several modes are accessible to set up and program the system, to monitor actual system performance, and to test the system or display warnings indicating system malfunctions or that new cassettes should be installed.

Abstract: A system of parallel compressors for compressing fluids miscible with oil. Means are provided for internally separating each compressor connected in parallel into a discharge chamber, a suction chamber, and a crankcase chamber, the chambers of each compressor being independent of one another. The crankcase chambers are connected in oil and gas flow communication with one another. A suction manifold is connected to the suction chambers, and each crankcase chamber is equalized with suction pressure. A discharge manifold is connected to the discharge chambers. Means for separating the oil from compressed fluids leaving the discharge chambers and returning the oil so separated to the crankcase chambers are also provided.

Abstract: An apparatus and method controls a dual piston pump for a liquid chromatography system so as to pump a flow of solvent through the liquid chromatography column at a constant flow rate and with a solvent composition which is substantially equal to the desired solvent composition despite changing conditions of compressibility of the solvent. A computer is used which measures the time it takes the pump shaft to move through an overlap region in the pump cycle when both pistons are simultaneously pumping as normalized to the time taken by the pump to move through a constant velocity portion of the piston travel defined by the user. This time is compared to the time stored in the computer for the particular flow rate used to measure the time defined above for the pump to move through the overlap region for an incompressible solvent at low pressure as normalized to the time taken by the input piston to move through the same user defined segment of the constant velocity portion of the travel of the input piston.

Abstract: The folded channel radial pump assembly (10) comprises a housing (12) having therein a stepped diameter bore (14) receiving a rotor (30). The rotor (30) is attached by way of a flexible coupling (50) with the output shaft (61) of an electric motor (60) attached to the housing (12). The rotor (30) includes one or more intake (26, 36) and exhaust (28, 38) ports, the ports (26, 28, 36, 38) being radially aligned and communicating with the stepped bore (14).

Abstract: A plurality of unloading steps for a compressor are achieved by providing the compressor with at least two cylinders having different displacements. By unloading different cylinders, the compressor output is better able to match system demand.

Abstract: A dual impeller recirculating pump having a plurality of simultaneously activated motors with counterrotating shafts coupled to the motors. An impeller is coupled to each shaft and rotated thereby. The impellers rotate within an impeller housing divided into individual sections, each section opening into a common outlet coupled so that counter rotation of the impellers forces water entering the housing sections out of each section into the common outlet which acts as a mixing chamber merging the fluid flow and thus increasing the flow rate and efficiency of the pump.

Abstract: An electric motor driven inline hydraulic apparatus comprises a common housing, a stationary shaft mounted in said housing and spaced pump cylinder block subassemblies that rotate around and are mounted on said shaft. Each subassembly includes a cylinder block and a plurality of circumferentially spaced pistons. The cylinder block subassemblies are positioned such that the pistons of one subassembly extend toward the other subassembly. A common yoke plate is mounted between the two cylinder blocks and bears the two groups of piston shoes, one on each of its two bearing surfaces. Each cylinder block is driven independent of and in direction opposite to the other by an electric motor integrally mounted such that its hollow rotor houses the block and drives it. All components described above are contained in one housing and operate submerged in hydraulic fluid.

Abstract: The stream of suction gas and entrained oil flowing from the evaporator in a parallel compressor refrigeration system is directed into a flow separator where it diverges and is expanded into a separation chamber of increased cross-sectional area. A takeoff conduit has an inlet end disposed generally in the center of the separation chamber which faces into the suction gas flow stream. Because of the location and size of the cross-sectional area of the inlet end of the takeoff conduit, a larger portion of the suction gas flow stream and oil entrained therein bypasses the takeoff conduit inlet than enters it. The separation chamber is in flow communication, at its outlet end, with the shell of the one of the compressors which is designated to receive a majority of the suction gas and oil entrained therein. The takeoff conduit is in flow communication with the other of the compressors.

Abstract: A proportioning pump with tandem diaphragm pumps each having a pumpage chamber connected with a source of supply and a mixer and dispensing nozzle, a piston pump for operating each of the diaphragm pumps, a common eccentric drive for the pistons of the piston pumps, the piston pumps having cylinder wall sleeves extending into the hydraulic fluid reservoir, the sleeves having refill ports therethrough communicating between the pump chamber and the reservoir, one of the sleeves being longitudinally adjustable, a double threaded rotary control for the longitudinal adjustable cylinder wall sleeve, bypass pressure relief valves and passages for the hydraulic fluid from the pump chambers returning fluid to the reservoir in the event of excessive pressure, and the pump motor having a variable speed drive for widely varying the speed of the pump.

Abstract: A multiple fluid pumping system uses two or more fluid pumps each driven by a pneumatic piston or plunger and cylinder combination whose piston top stroke and bottom stroke positions are detected by reed switches in combination with a magnet attached to the piston. The top stroke reed switches are connected in series with one side of a two position pneumatic solenoid valve while the bottom stroke reed switches are connected in series with the other side of a two position penumatic solenoid valve. The circuit is designed to prevent one of the pistons from changing the direction of its stroke prior to the other piston reaching the end of its stroke. A further embodiment utilizes a magnet mounted on one pneumatically driven piston or plunger and a pair of reed switches mounted on the other penumatically driven piston or plunger to prevent one piston or plunger from moving faster or slover than the other piston or plunger.

Abstract: An integral combination of two motor pumps wherein two pumps 12, 14 are operated preferably from the motor shafts 41, 43 of a centrally located, pancake-type, d.c., brushless electric motor 10, the entire combination being housed in a unitary casing. The stator 22 is located within a central peripheral cavity between a pair of rotor faces 26, 28 in which are set spaced permanent mangets 32, 34 which react with the commutated d.c. fields of the stator coils to rotate the rotors 36, 38. Each rotor, e.g. 38, is integral with a motor shaft section which is integrally coupled with a pump shaft, e.g., 44. The pump shaft 44 supports an inducer 46 and an impeller 48 which pump a fluid that is also sent through passages in the motor 10 to lubricate the sleeve bearings 54 and to cool the motor components. The speeds of the rotor 36, 38 can be individually adjusted, for example, by adjusting the number of permanent magnets 32, 34 in each rotor face 26, 28.

Abstract: An actuator control system is disclosed using fluid dispensing means to selectively add or remove fluid from a closed actuator system, whereby the movement of the actuator is volume rather than pressure responsive.

Abstract: A fitting for use downhole in a well for connecting a pair of well pumps one above the other to the bottom of a drop pipe or the like, so that each of the pumps may discharge well fluid into the drop pipe, comprises an elongate housing with an inlet at its bottom end for connection to the discharge of one of the pumps, an outlet at its upper end for connection to the drop pipe, an elongate pocket portion between the ends for receipt of the second pump, the pocket portion defining a bypass conduit for well fluid flowing from the first pump through the fitting to the outlet, and a further inlet for connecting the discharge of the second pump into the fitting at its upper end. The fitting is suitable for use in well casings down to a diameter of about six inches and the design of the fitting promotes smooth non-turbulent flow of well fluid therethrough.

Abstract: A two-machine aggregate, preferably a dual-pump aggregate, with two swash plate axial piston pumps arranged coaxially to each other back-to-back is provided, where an auxiliary shaft is provided for the purpose of offering a connection and attachment possibility for at least one additional pump, which shaft runs parallel to the coaxial shafts of the two machines of the two-machine aggregate and is driven by means of a torque transfer unit, in which case the auxiliary shaft and the torque transfer unit are located in an intermediate component which extends between the two machines of the two-machine aggregate and projects above them.

Abstract: A variable speed ratio system for the controlled dispensing of a plurality of non-compressible fluids at high pressure, principally for use in reaction injection molding processes. Each of the pistons in two or more displacement cylinders that contain the fluids to be mixed is connected via a rack gear to the piston of a hydraulic driving cylinder, all hydraulic cylinders being connected to a common source of pressure. A variable speed change gear train connected to each rack gear will control the speed ratios of the displacement pistons irrespective of the fluid viscosities or mixing orifice sizes while the gears are subjected to only the differences in forces acting on the displacement piston rods.

Abstract: A duplex compressor arrangement for shipboard application is provided with a central oil pickup to minimize the effects of trim on the sump. Additionally, the compressor crankcases are connected to the sump via return lines and equalizer lines which can act as secondary drain lines under the proper trim conditions.

Abstract: A combined power steering pump and vacuum pump assembly is disclosed wherein a vented reservoir is connected to receive the discharge of the vacuum pump as well as supply the fluid for circulation by and lubrication of the power steering pump. A sealing arrangement seals the vacuum pump from the power steering pump when the pumps are stopped but provides limited delivery of the fluid from the power steering pump to the vacuum pump when the pumps are running whereby the fluid in the power steering system is prevented from draining into the vacuum pump when stopped and is delivered thereto when running to lubricate same and is then delivered with the discharge air to the reservoir so that there is no loss of the fluid from the power steering system in lubricating the vacuum pump.

Abstract: The invention is directed to a dual-piston reciprocating pump assembly which includes two opposed substantially identical reciprocating pumps, a housing within which the pumps are mounted, a cam mounted on a cam shaft which is driven through a coupling by a stepping motor, each of the pumps including a piston assembly comprising a piston body having a piston end, the other end of the piston body being in the form of a yoke which is mounted for reciprocating motion in the housing, a cam follower carried between the arms of the yoke for engaging the cam face of the cam, a cylinder head having a piston cylinder therein for receiving the piston end, the housing having an end opening for receiving said cylinder head, a guide bushing mounted in the cylinder head for facilitating the assembly of the piston end, an inner bearing bore for the piston end disposed adjacent the guide bushing, a high-pressure seal disposed adjacent the inner bearing bore, the piston end having substantial radial end play, and a piston spr

Abstract: The invention relates to a circuit for ventilating and filtering the medium contained in a confinement enclosure (10) and also a method for sterilizing such an enclosure and its supply and discharge filters.An emergency or standby circuit is associated with the circuit ensuring ventilation and filtration under normal operating conditions and which comprises a supply pipe (20) and a discharge pipe (12), equipped with a suction fan (14). The said emergency circuit comprises the same pipes used in the opposite direction under the action of a suction fan (28) located in supply pipe (20), whereby said fan (28) can be automatically controlled by a pressostat (30). Sterilization is performed chemically, using a sterilizer which is connected to the supply duct between a valve and the supply filters disposed downstream of the valve. The sterilizer delivers a sterilizing agent which passes successively through the supply filters, the enclosure and the discharge filters.

Abstract: At least two radial piston pumps having a common eccentric rotatable within an eccentric chamber of the pump housing supply pressurized fluid to separate fluid circuits. The eccentric chamber is divided into separate fluid delivery compartments to which fluid is conducted from a common suction port by the pumps through passages that dampen the transfer of pressure fluctuations between the fluid circuits.

Abstract: A back-up system is provided for a pumping plant or a pressure reservoir system used to maintain insulating oil under pressure in high voltage submarine power cables which includes a gas driven membrane pump to insure a small outflow of oil at a rupture point in the power cable to prevent water from penetrating the cable. The proper operation of the membrane pump is insured by introducing degasified oil at the drive side of the pump during the stand-by and test modes of operation of the back-up system.

Abstract: A pump, for injecting chemicals into a well, comprising a pivot arm for synchronous movement with a well pump. The pivot arm causes reciprocation of a plunger within the body of the chemical pump. The plunger, during its upward stroke causes the entry of chemicals from an outside source into the pump body and, during its downward stroke causes the exiting of the chemicals into the well.

Abstract: A portable positive displacement respirator/ventilator is provided for both a pressure sigh and a volume sigh of predetermined duration and frequency by providing a variable length crank arm connecting a piston through a connecting rod by mounting the connecting rod on a circular toothed gear, pivoting the gear for movement at its center and driven on its outer edge with a separate motor driven pivot gear which when moved relocates the effective length of movement of the point of attachment of the connecting rod thereby changing the volume swept by the piston for the same arc of reciprocal movement of the larger circular toothed gear enabling both a volume change or a volume sigh with the device. A cooperating multiplicity of adjustable pressure regulating valves where at least one can be intermittently closed during the operation of the device regulates ventilation pressure or breathing pressure and sigh pressure.

Abstract: Parallel connected compressors are provided with an oil management scheme in which an oil equalization port on one compressor is connected via an oil return solenoid operated valve within a small diameter line to an injection port of a second compressor, and vice versa. When the oil level in one compressor drops to a level sensed by an oil float switch, the oil float switch changes state, the oil return solenoid operated valve is opened, feeding its injection port and energizing a one minute on delay timer. Failure of the oil float switch to reset itself causes the compressor to go off on oil failure, and the oil return solenoid operated valve is closed. If the oil float switch resets itself at any time during the first minute, upon resetting, an off delay timer is energized to keep the oil return solenoid operated valve open for an additional minute, and the compressor continues to operate.