Abstract: A scroll type compressor including a housing, a fixed scroll which is joined to the housing and including a first end plate from which a first wrap extends and an orbiting scroll which includes a second end plate from which a second wrap extends. The wraps interfit at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets. The first end plate is formed with a plurality of pairs of holes, the holes of each pair of holes being placed at symmetrical positions. The most inwardly placed hole is placed at a location defined by involute angles within the area defined by .phi.end-2(n-1).pi.>.phi.1>.phi.end-2n , where .phi.end is the final involute angle of the wrap which extends from the end plate having the holes, .phi.1 is the involute angle at which the hole is placed and n is the amount of pairs of holes. The most outwardly placed hole is placed at a location defined by involute angles within the area defined by .phi.n-1+2.pi.>.phi.n>.

Abstract: A modular three block assembly provides unloading control for a hydraulic cylinder functioning to variably position a slide valve on a helical screw rotary compressor. A first compressor block is fixedly and sealably mounted within the hermetic compressor outer casing and has through holes leading to a first tube connected to a source of oil under discharge pressure forming the hydraulic fluid for the hydraulic cylinder, a second tube connected to the hydraulic cylinder and a third tube to the suction tube returning low pressure vapor to the compressor suction side. A needle valve block is fixedly mounted to the external face of the compressor block and bears within longitudinal through passages paired needle valves determining the load and unload flow rates for the hydraulic fluid passing through said compressor block through holes.

Abstract: A scroll type compressor is disclosed. The compressor includes a housing having a fluid inlet port and an outlet port. A fixed scroll is fixed within the housing and has a circular end plate from which a first wrap extends. The end plate of the fixed scroll partitions the inner chamber of the housing into a front chamber connected to the fluid inlet port and a rear chamber. The rear chamber is divided into a central chamber connected to the fluid outlet port and an outer chamber. An orbiting scroll, which is disposed in the front chamber, also has a circular end plate from which a second wrap extends. Both wraps interfit at angular and radial offsets to form a plurality of line contacts to define at least one pair of sealed off fluid pockets. The end plate of the fixed scroll has at least two holes which are placed at symmetrical position and connect the fluid pockets to the outer chamber. The end plate also has a communicating hole which connects the first chamber and the outer chamber.

Abstract: A rotary compressor is provided with a rotary valve arranged rotatably in the housing unit. The rotary valve is partially exposed to an interior space of the housing unit. The interior space is divided into a plurality of variable working spaces. A return port is formed in the rotary valve for feeding a cooling medium into an inlet port from the working space. A quantity of the cooling medium discharged from the working space through an outlet port is changed in accordance with the rotation of the rotary valve controlled by the actuator.

Abstract: A variable flow reversible vane pump having a rotor with slidable vanes, a shaft providing rotary power take off for the rotor and a cam ring wherein said rotor rotates with the vanes engaging the inside of the cam ring. A case encases the cam ring and a front bearing plate connects to the front of the case. A rotary valve surrounds the shaft and flushes against the cam ring and the rotor with slidable vanes and has a structure defining a plurality of directly opposed channeled arcuate grooves, at least one port in each of the opposed grooves, and a plurality of gear teeth along part of the periphery. A rear bearing plate encloses the other end of the cam ring and the rotor and has a structure with rear plate apertures in communication with one of the opposed arcuate grooves and the port therein of the rotary valve plate. A rotatable gear is lodged within a gear channel of the case and meshes with the gear teeth along the periphery of the rotary valve plate.

Abstract: The invention relates to a valve arrangement for capacity control of an oil-injected screw compressor. One or more piston valves are arranged one after the other in the axial direction of the rotors at the portion of the rotor barrels where the internal compression phase occurs. The compressor control valves are actuated by the discharge pressure, which in their turn open or close the piston valves. When the piston valves are open, a portion of the gas in the compression space is discharged to a bleed off passageway and it flows back to the inlet port of the compressor so that substantially no compression work is spent on this portion of the gas.

Abstract: There is disclosed a scroll-type machine specifically suited for use as a gaseous fluid compressor. The machine has intermediate relief valve means providing variable pressure ratio characteristics to thereby improve efficiency, as well as protect against overcompression.

Abstract: A scroll type fluid machine having two scroll members each having an end plate and a spiral wrap formed on the end plate, the scroll members being coupled to each other such that the wraps thereof mate with each other. One of two scroll members being adapted to make an orbitary movement with respect to the other scroll member while being prevented from rotating around its own axis, so as to form at least one working chamber of different pressures between two scroll members. At least two pressing force imparting chambers are formed on the opposite side of the orbitary scroll member to the wrap.

Abstract: A cylinder extends into a container containing fluid to be dispensed and includes a pressure accumulating valve at the internal end. A piston sliding in the cylinder includes an air suction valve at the internal end and a pressure chamber is formed between the piston and the cylinder. An elastic piece is axially flexible and is attached to the bottom of the piston. The air suction valve has an axially flexible valve body. A stem fixed at one end to the bottom of the elastic piece is extended into the piston at the other end, and has a pushing part at the other end to release the air suction valve from the valve seat by contacting the valve body when the elastic piece is moved toward the air suction valve.

Abstract: An air switch comprises a switch body having a recess thereon and a switching member having an output connection port. The recess is connected to vacuum and pressure outlets through passages in the switch body. The vacuum passage is connected to a port on the wall of the recess while the pressure passage is connected to a partially circularly extending channel on the recess wall. The switching member is rotatably received in the recess and includes a radially extending channel on its inner wall. Positioning of the switching member in the vacuum or pressure modes places the member channel in fluid communication with either the vacuum port or the channel on the recess wall. When in the vacuum mode, the pressure channel is vented to the atmosphere and when in the pressure mode, the vacuum is similarly vented. When in the minimum pressure mode, a portion of the pressure is vented to the atmosphere although this pressure venting is reduced to zero when the switching member is in the maximum pressure mode.

Abstract: A scroll type compressor is disclosed. The compressor includes a housing. A fixed scroll is joined to the housing and includes a first end plate from which a first wrap extends. An orbiting scroll also includes second end plate from which a second wrap extends. The wraps interfit at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets. The first end plate is formed with at least two holes which are placed at the symmetrical positions. A first of the holes is placed at a location, defined by involute angles, within the area defined by .phi. end >.phi.1>.phi. end-2.pi., where .phi.0 end is the final involute angle of the wrap which extends from the end plate having the holes, and .phi. 1 is the involute angle at which the first hole is placed. The second hole is located at an involute angle approximately .phi.1-.pi.. A control mechanism controls the opening and closing of the holes to thereby control the capacity of compressor.

Abstract: The high pressure end wall of an axial flow helical screw type compressor has a slide member which is movable transversely of the rotors for controlling the size of the discharge passage through the end wall and is controlled by sensing means responsive to the pressure at the end wall and in the discharge area in order that full compression which is substantially equal to the pressure at discharge may be obtained.

Abstract: A control device for regulating the capacity and the built-in volume ratio of a helical screw rotor machine comprises at least one additional valve member which is axially aligned with first and second valve members in the screw rotor machine, the additional valve member being movable between the positions in which said additional valve member contacts one or both of said first and second valve members to form an extension of either or both of the first and second valve members. The additional, first and the second valve members are connected to the operating device to permit displacement thereof. This permits varying the length of the second valve member (the slide valve) in one or more steps, which in turn means that it is possible to displace the gap between the first and second valve members without moving the high pressure end of the second valve member (the slide valve).

Abstract: A valve for compressor clearance or by-pass control for a gas compressor having a compressor cylinder which includes a tubular member having a bore communicating with the compressor cylinder, an outer surface and an opening. A valve sleeve receives the tubular member therein and is slidably movable with respect thereto between an open position whereat one of a clearance pocket and a suction chamber communicates with the compressor cylinder through the opening and a closed position closing the opening. A plug is positioned in the tubular member bore and reduces the amount of clearance in the compressor cylinder. Actuator means is provided for moving the valve sleeve between its open and closed positions. The tubular member is attached to an outboard side of a suction valve assembly, and the bore thereof communicates with a passage extending through the suction valve assembly and opening into the compressor cylinder.

Abstract: A discharge flow control rate valve for a multiple cylinder type reciprocating pump has a flow rate control valve associated with two cylinders of the pump. The flow control valve has a bypass passage connecting the suction side of the pump with a stepped cylinder chamber provided in the body member of the control valve. A needle valve fitted with a separate valving element is reciprocably disposed in the stepped cylinder chamber and operates to return a part of the fluid in the first cylinder or in the first and second cylinders to the suction side of the pump as a function of the intrusion distance of the valve into the cylinder chamber so as to modify the overall discharge flow rate of the pump.

Abstract: Apparatus for unloading a scroll compressor to modulate its capacity by separately controlling fluid flow into first and second inlets. The first and second inlets are disposed diametrically opposite each other in a fixed scroll plate, and are enclosed by a perimeter wrap which extends from the radially outer end of the fixed spiral shaped wrap element. A compliant sealing member is provided between the inner surface of the perimeter wrap and the outer flank surface of the orbiting scroll wrap to interrupt fluid flow between the two inlets through this area. Valves connected to the first and second inlets selectively control the flow of suction fluid into fluid pockets being formed between the radially outer ends of the orbiting and fixed wrap elements to unload the compressor over an extended range of its rated output capacity.

Abstract: An apparatus and a method for controlling the capacity of a reciprocating compressor by altering the effective stroke length of the working piston of the compressor is disclosed. The working piston of the compressor has a piston opening extending through the top surface thereof. A bypass piston having a cylindrical portion sized to block the piston opening and a reduced cross-sectional portion designed to allow gas to flow through the piston opening is provided. By adjusting the position of the bypass piston the effective stroke length of the working piston may be controlled to allow modulating compressor operation.

Abstract: A piston type fluid pump which can maintain its prime even though the source of fluid from which the pump draws its supply becomes empty. The pump is capable of pumping its discharge into a pressure vessel as well as to the atmosphere if desired. The pump assembly includes a discharge chamber that receives discharged fluid from the pump and for ultimate delivery to the outflow of the pump assembly. The discharge chamber is of a volumetric size at least equal to or greater than the volume of the effective pumping chamber of the piston so that any air that enters the pumping chamber from the supply or inlet side of the pump remains at the top of the pumping chamber and is discharged into the discharge chamber and the pumping chamber remains full of fluid and consequently primed.

Abstract: A compressor is provided which has a housing formed with a volume control chamber located in the vicinity of the discharge port and within which a valve is mounted, a first port communicating the volume control chamber with a pumping chamber defined within the housing, and a second port communicating the volume control chamber with the suction port. The valve is disposed so as to open selectively the first port alone or both the first port and the second port, to thereby make it possible to control the discharge rate of pressurized gas or interrupt discharge of same without interruption of driving of the gas pressurizing member of the compressor for compression of gas such as a rotor or a piston.

Abstract: A system for supplying fuel to an atomization fuel oil burner nozzle from a fuel pump at a rate less than that rated for the nozzle for burning of less fuel while achieving good combustion. The fuel is delivered to the nozzle at a pulsing frequency which is dynamically matched to intermittent pressure pulses within the fuel pump to create resonant pressure peaks at the nozzle. The fuel pump creates a pressure pulse each time a tooth of one gear of the pump makes full penetration into the space between a pair of teeth of a coacting rotatable ring gear. Rotatable valving structure, including gear ports in the rotatable ring gear pulses fluid flow to the nozzle by alternately connecting a fluid outlet of the pump to either a pressure port within the pump at the time of a pressure pulse or to the fuel pump inlet with the pressure peak of the pulsed flow being phased together with said pressure pulse.

Abstract: A gas compressor of the scroll type is disclosed wherein unloader means are provided for selectively varying its capacity by effectively delaying the point at which the closed moving volumes defined between the wrap elements begin compression. To this end, passage means extend through the end plate means of the compressor from a location in communication with the closed moving volumes to a location in communication with working gas normally at suction pressure during operation of the compressor. Valve means are provided for selectively blocking flow through the aforementioned passage means, whereby the compressor operates at a relatively high capacity; and for permitting flow through the passage means, whereby gas is exhausted via the passage means to suction pressure as the closed moving volumes progress radially inwardly to a predetermined position at which compression is permitted to begin.

Abstract: A reciprocating piston swash plate refrigerant compressor is disclosed having a variable pumping capacity control arrangement wherein the pumping capacity is varied by effecting communication between the compressor's suction side and one or more of the cylinders during compression. Such communication is provided by a bypass valve controlling an additional suction port formed in the head end of the cylinder in parallel with the normal valve controlled suction port therefor. The bypass valve is urged to open the bypass port by cylinder pressure acting directly and continuously on a small pressure responsive area thereof and is urged to close the bypass port by discharge pressure delivered to act on a large pressure responsive area thereof under the control of a separate control valve which alternatively communicates suction side pressure with the large pressure responsive area when it is desired to permit the bypass valve to be opened by the cylinder pressure.

Abstract: A process to supercharge and control a compressor comprising a single screw co-operating with at least two pinions in order to constitute as many partial compressors as there are pinions, such partial compressors operating in parallel and one of them at least being provided with a delivery control device, wherein the supercharging flow is injected into only one of the partial compressors and the delivery of the compressor is controlled from maximal delivery by reducing at first the deliveries of those partial compressors into which the supercharging flow is not injected.

Abstract: A method and apparatus for controlling a resonant piston compressor of the type comprising an electrodynamic linear reciprocating motor adapted to be driven cyclically by an alternating current power source and having at least one piston coupled to and adapted to be driven within a selectively valved working cylinder by the linear reciprocating motor in synchronism with the frequency of the alternating current power source. Enclosed volumes of gas act as resilient gas springs coacting with the piston and with the linear reciprocating motor to form a mechanical resonant system having a resonant frequency substantially centered on the frequency of the alternating current power source. A midstroke porting arrangement is responsive to the position of the resonant piston for selectively communicating a gas spring control valve with said gas springs.

Abstract: A gear machine comprises two helical gears (1, 2) in mutual mesh for compressing or pumping a fluid. The suction side of the machine can be made conventionally. The outlet port (4) of the machine is made as a plurality of holes (14), extending in towards the meshing zone at one side of the gear pair. The plurality of holes opens at one end (14a) within a Y-shaped area comprising the union of the surfaces which are each defined by the respective gear top and bottom circles (K, L) between a plane (P) through the axes of the gears and a gear radius (R) forming an angle to the axis plane at most attaining B .times. (1/R) .times. tangent .beta., where B is the width of the gear pair, R is the outside circle radius of the respective gear, and .beta. is the helix angle of the gears. At their other ends (14b), said holes are connected to a duct (6) at axially separated places in the duct, in the same order as they in the peripheral direction of the gears, open out onto said end surface.

Abstract: A fluid system, especially for a transmission having a hydrodynamic torque converter and a mechanical change speed gear box downstream therefrom. For supplying pressurized fluid to the working chamber of the torque converter, the clutches and brakes of the torque converter and the servomotors which control the gear steps of the downstream mechanical change speed gear box, there is provided a pressure system having first and second low pressure pumps and preferably an auxiliary high pressure pump. The first low pressure pump delivers fluid continuously for delivery to the working chamber of the torque converter and to the servomotors. The second low pressure pump can deliver pressurized fluid through a one way valve to the discharge side of the first low pressure pump or alternatively its output can be bypassed directly to the input of the second low pressure pump.

Abstract: A grease gun is fed from a constant supply under pressure. The gun has a hand-pumped lever for delivering shots of grease either at high pressure and low volume or low pressure and high volume depending on a changeover valve. Air bleeds from the gun through the nozzle by a single pump of the lever. The lever causes a pushrod to open a one way valve allowing grease to travel entirely through the gun to the nozzle.In another version the pushrod is replaced by a cone valve. Both versions are for single handed operation.

Abstract: A variable displacement balanced vane pump includes an alternate flow passage for fluid being compressed in an intervane chamber whereby the excess portion of the fluid is by-passed from the pump discharge zone to the pump inlet zone without appreciably increasing the pressure of the excess fluid portion to minimize the required pump input energy.

Abstract: This invention relates to a rotary fluid machine (e.g. a compressor) of the single screw type, the single screw cooperating with rotary toothed gate rotors to define fluid-filled chambers whose volumes vary as the screw rotates. The invention is concerned with the provision of two or more capacity-regulating valves provided for the chambers of such a machine, the operating members of such valves being arranged such that one member can be moved independently of the other or others.

Abstract: An apparatus for supplying molten bituminous material to an elevated level in which the molten bituminous material is pumped by a pump through a valve and up an upstanding supply pipe to the elevated level the supply pipe is in communication through two ports of the valve with the interior of the vat for free draining under gravity of the body of bituminous material from the supply pipe back to the vat when the supply of molten bituminous material to the elevated level is discontinued. While the supply of molten bituminous material to the elevated level is discontinued the bituminous material is pumped through two further ports of the valve for recycling back into the vat, preferably at an end of the vat remote from the pump inlet in order to ensure substantially complete circulation of the molten bituminous material within the vat.

Abstract: A hydrostatic transmission control system including a variable displacement pump driving a constant displacement motor arranged in a hydraulic circuit having a controlled by-pass valve interconnected for positioning the pump swash plate in two established positions corresponding respectively to a stand still position or a full speed position of the motor. A thermosensitive element is coupled to the valve control spool for bypassing the flow of the pump in the event of motor jamming.

Abstract: A hydraulic motor of the Gerotor-type which is designed for rotation in both the clockwise and the counterclockwise direction and which includes a pair of relief valves arranged to protect the motor shaft seal, irrespective of the chosen direction of rotation. The Gerotor element also includes a pair of motoring grooves which cooperate with a feed channel formed in the surface of the motor end plate and with a corresponding shadow feed channel on the opposite motor front plate to equalize the forces on the rotor element of the Gerotor and thereby prevent distortion and binding of the rotor element due to thrust forces thereon.

Abstract: In a rotative machine for fluid circulating between an inlet and an outlet comprising a plate with spiral-like passages formed by rib members, the extremities of the passages emerging into a central chamber and into a perpheral chamber, respectively, and a disc rotating in relation to the plate around a common axis and carrying vane wheels on its face in front of the plate, the vane wheels having vane members which circulate in the passages of the plate, the fluid compartments being defined by the vane members in the passages and further defined by the cooperation of the conjugated surfaces of the ridges of the ribs bordering the passages and of the disc, the improvement which comprises: means to put an outlet of the passage in communication with the discharge fluid or, alternatively, in communication with the inlet of the fluid.

Abstract: Disclosed is a constant pressure spraying apparatus in which the motor driven pump piston moves within a pump housing and valve assembly which are carried by a cap or closure for the fluid tank forming the reservoir of fluid to be pumped and sprayed. The cap structure is shaped so as to provide a drain sump for fluid leaking past the pump piston.

Abstract: A low well yield control system and method for preventing over pumping of wells and other fluid reservoirs. The control is positioned in the reservoir and includes a plurality of relief valves which are opened to replenish liquid in the reservoir from the pumped liquid in the event the liquid level is lowered relative to a float.

Abstract: A device is provided for monitoring and controlling the above-ambient pressure in a system by comparing a net pressure force, produced by the system pressure on a pair of diaphragms having unequal areas, with a net spring force produced by a pair of opposed springs which clamp together a valve member and a valve seat in a pressure-relief member. The valve seat is connected by a passage to a port which is connected to the system pressure. While thus clamped together, the valve member and the pressure-relief member travel together through most of the total stroke created by movement of the pair of diaphragms and activate a microswitch for admitting additional fluid to the system when the system pressure is insufficient. If the net pressure force is sufficiently greater than the net spring force because of excessive system pressure, a port is opened when the valve strikes a stop and the pressure-relief member continues to move.

Abstract: A gear pump which comprises a casing provided with an inlet port communicating with an intake chamber, and a delivering port communicating with a delivery chamber. A drive gear is mounted in meshing engagement with a driven gear, each gear being placed in a corresponding bore in the casing, the gears being placed in the flow path between the intake chamber and the delivering chamber.One of the gears contains a central bore with passages which connect the bore to the gaps between adjacent teeth of the gear. A spool is slidable in the central bore for controlling fluid communication through the passages and the movements of the spool are controlled by the pressure difference between the fluid pressure in the delivery chamber and an operating pressure in such a way that the spool is held in a closure position in which the communication through the passages remains blocked as long as the delivery of the pump remains below a given level corresponding to a predetermined pressure difference.

Abstract: The present hydraulic system for driving a submersible pumping unit has an above-ground pump for pumping oil through a hydraulic motor in the submersible pumping unit, and a check valve between the above-ground pump and that hydraulic motor to prevent the reverse flow of oil after the submersible pumping unit is turned off. A pressure regulating valve limits the oil pressure to the hydraulic motor. The inlet flow to the above-ground pump is filtered.

Abstract: A reciprocating vane rotary compressor for an automotive air conditioning system wherein the compressor capacity may be varied in response to the evaporator pressure or temperature such that the evaporator pumps only the amount of refrigerant required at moderate ambient temperatures. The compressor has a circumferentially adjustable modulation ring mounted in concentric relation with the internal compressor chamber surface. The ring, having by-pass port means, may be advanced in the direction of rotation of the rotor, with the port means operative to delay the time that the chamber goes under compression. By varying the induction cut-off point of the ring by-pass port means, the compressor chamber undergoing pre-compression returns gas via a suction transfer passage in the housing to the compressor suction cavity. The compressor rotor is mounted on a unique overhanging stub shaft arrangement to provide a simplified single journal bearing location for the rotor.

Abstract: A pump comprising a body having at least one chamber and preferably two axially spaced and aligned pumping chambers, each such pumping chamber communicating at opposite ends respectively with a pump inlet and a pump outlet and containing an actuator reciprocable longitudinally of the pumping chamber by drive means, the actuator having a rigid main central portion and a peripherally extending elastic sealing ring in non-sliding fluid-tight engagement with a lateral wall of the pumping chamber and having mounted thereon actuator valve means controlling the flow of fluid from the inlet to the outlet of the pump, the pumping chambers communicating at their outlet ends with manifold passageways in the body of the pump which in turn communicate with respective passageways in an outlet duct situated on opposite sides of a longitudinally extending web therein terminating at a position spaced from the downstream end of the outlet duct to provide for cyclic flow of the pump fluid out of one pumping chamber and into the

Abstract: A rotary gas compressor or expansion motor with a housing having circumferentially spaced inlet and outlet ports. An outer cage or sleeve rotor has alternate slots and teeth. An inner lobe rotor has lobes which mesh with the slots of the cage rotor as the two rotate. The space between the two rotors is filled with a crescent-shaped housing member. The slots, teeth and lobes of the rotors are helical.

Abstract: A fuel injection valve for an internal combustion engine includes a fuel storage compartment and a pressure chamber from which a reciprocating pump piston delivers fuel to the engine's fuel lines. The fuel conduit between the storage compartment and the pressure chamber can be closed off by an electromagnetic valve. To permit engine operation even when the electrical system is non-functional, the magnetic valve is of the normally open type, held open by a spring. In the energized state, the valve closes off the fuel conduit and its closure is aided by the fuel pressure gradient across the valve.

Abstract: A fuel injection pump for internal combustion engines has a simultaneously reciprocating and rotating pump piston which aspirates fuel from a fuel compartment and then delivers it under pressure to engine fuel lines. An electromagnetic valve can obturate the conduit between the fuel compartment and the pressure chamber of the pump, thereby shutting off fuel delivery. To permit manual override of this shut-off, the electromagnetic valve may be partially unscrewed from the pump housing, thereby lifting the valve closing member from its seat and permitting fuel flow. In another version, an externally accessible central valve bolt partially lifts the valve-closing member from its seat.

Abstract: A rotary compressor apparatus having a housing with a rotor eccentrically mounted therein and such rotor includes a plurality of sliding vanes which define constantly changing compression pockets as the rotor is rotated. The apparatus includes a plurality of ports which may be opened to permit full unloading when starting the compressor and which may be selectively closed to control the quantity of gaseous matter being compressed. The apparatus also includes a high pressure oil injector at each end of the rotor for sealing such ends to prevent loss of compression.

Abstract: An unloader assembly for a gas compressor having a compressor suction chamber and a compressor cylinder with a compressor piston slideable therein for effecting one-way gas flow through a suction valve assembly mounted in the compressor suction chamber, said suction valve assembly having a central passage therethrough. An unloader piston is slideably movable in the central passage of the suction valve between a first position closing a plurality of ports in the suction valve each providing communication between the suction chamber and the suction valve central passage and a second position opening the ports. A clearance bottle is mounted on the compressor and a valve controlled aperture permits communication between the suction chamber and the clearance bottle until closed by a clearance bottle valve.

Abstract: A valve device is disclosed for unloading pressure from a compressor of the type utilized in a medical respirator. The device is formed with a cylindrical chamber containing a compressible elastomeric member. Inlet and relief ports of the valve open into the chamber, and the inlet port is connected with the outlet of the gas compressor. Bistable actuator means is provided for moving a plunger within the chamber which in turn causes the cylindrical member to assume either a compressed or uncompressed state. In its uncompressed state a radial clearance between the outer wall of the elastomeric member and the chamber provides a flow path between the inlet and relief ports to bleed pressure from the compressor. In its compressed state the elastomeric member expands to occlude the flowpath and prevent pressure bleed-off from the compressor.

Abstract: A control system for preventing over-pumping of wells using submersible pumps. When the pump lowers the level of the water in the well, the control automatically diverts some or all of the water pumped back into the well to assure that sufficient water is available in the well for pumping. In this way, pump cavitation is eliminated and water is pumped from the well either at a rate equal to the capacity of the pump or, if the flow of water into the well is less than the capacity of the pump, at a rate equal to the flow of water into the well.

Abstract: A rotary displacement compressor having a driven cylindrical rotor inside a casing provided with spirally-extending grooves, and at least one gear in sealing engagement with the teeth of the rotor in which the axis of rotation of the gear intersects the axis of rotation of the rotor and in which the gas to be compressed is drawn-in through the open ends of the grooves at one end of the rotor and an exhaust port is located in the wall of the casing near the other end including a second port in the wall casing at the same axial height as each exhaust port, the port being in communication with the intake side of the compressor via a return pipe, and a regulating ring to control the size of the return port and the exhaust port.

Abstract: This invention relates to a variable capacity type gear pump which is capable of operating efficiently by flowing out by-passed liquid under extremely low pressure to adjust or control the amount of feed-out liquid. This is accomplished by providing the walls of the casing (housing) of the gear pump with ports or slits, which ports or slits are connected to a controlling valve in order to remove the desired amount of by-passed liquid.

Abstract: A hydraulic fluid circuit comprises an engine-driven pump for communicating pressurized fluid through a combined unloading and relief valve and to an implement control circuit of a construction vehicle. Actuating means are provided for selectively opening the valve during engine start-up to reduce fluid pressure in the valve and implement control circuit to a first predetermined level. An override means is operatively connected to the actuating means for preventing the valve from opening when the fluid pressure exceeds a second predetermined and operating level which is higher than the first predetermined level.