Abstract: A progressive cavity drilling motor is disclosed with a multiplicity of helically formed conduits positioned in a resilient stator. The conduits are placed between an inner wall of a motor casing and a helically formed through hole formed by the stator. The conduits are located in parallel with each of the semi circular lobes thereby reducing the thickness of the elastomer in the lobe area resulting in a reduction of the hysteresis in the elastomer that is caused by cyclic stress reversals of the stator during motor operation. The conduits additionally divert a portion of the drilling fluid through the stator conducting heat therefrom. In addition, one or more of the conduits may be utilized as a communication channel therethrough for measurement while drilling capabilities.

Abstract: A composite stator construction for a downhole drilling motor which provides improved sealing and distortion properties. The elastomer which maintains the sealing/pumping action of the motor is applied in a uniform thickness to a rigid metallic form. In the stator, the rigid former has the basic configuration of the stator and is mounted within the casing of the motor. In the rotor, the elastomer can be applied directly to a metallic rotor core. The basic geometry is provided by the metallic former thereby reduces distortion of the lobes under increased torsional forces.

Abstract: A sliding-vane rotary compressor including a drive shaft having one end portion rotatably supported by a bearing fitted in a central hole in a rear block, the opposite end portion of the drive shaft extending loosely through a central hole in a front block and being rotatably supported by a bearing fitted in a central bore in a front head, the front head having a plurality of support ribs held in abutment with an outside end face of the front block for supporting the front block. With this construction, the front block and the front bearing are thermally separated from one another, so that a bearing clearance between the front head and the drive shaft is kept always constant even when the front side block is subjected to a high temperature. In addition, by the use of the support ribs, a thinner side block can be used.

Abstract: A two stage dry primary pump comprises, in a single common stator: a screw pump at its low pressure end; and a fluid viscous effect, single rotary screw gas exhaust pump at its high pressure end; with a link duct providing communication between the screw pump and the viscous effect, single rotary screw gas exhaust pump. The invention is applicable to vacuum pumps.

Abstract: The scroll gas compressor of the invention is so constructed that an enclosed container is partitioned by a fixed scroll member into a high pressure chamber and a low pressure chamber for gas-liquid separating intake refrigerant and storing it, the low pressure chamber being disposed at the lower portion and the high pressure chamber at the upper portion of enclosed container, the high pressure chamber disposing therein a drive unit related to a scroll compression mechanism and a lubricating oil sump, and the fixed scroll member serving also as part of the bottom of the lubricating oil sump, thereby providing that is small-sized, wide in an operational speed range, and superior in durability, and that prevents absorption of heat and noise propagation from the low pressure chamber serving as both the gas-liquid separation chamber and the reservoir of fluid, thereby improving the compression efficiency and lowering noise.

Abstract: In a mechanical supercharger having rotors mounted on rotor shafts, the rotor shafts are rotationally and axially supported in the supercharger housing by first and second sliding bearings. The first sliding bearing includes an inner part fixed to each of the rotor shafts and having both a cylindrical part and a radially extending, disc-like plate part. The first bearing also includes an outer part having bores closely surrounding the cylindrical parts of the inner part and axial surface facing an axial surface of the plate parts of the inner parts. A retainer engages the outer part and encloses another axial face of the inner part to form bearing spaces into which oil can be pumped for lubricating the sliding bearing. The pump can be in the form of spiral grooves in the radially extending, disc-like plate part.

Abstract: A twin-shaft vacuum pump includes a pump chamber, a pair of rotary pistons disposed in the pump chamber, and plates which laterally delimit the pump chamber, and a housing ring which peripherally delimits the pump chamber. In order to increase the ability of the pump to withstand thermal stresses, the housing ring and the rotary pistons are made of different materials, with the coefficient of expansion of the piston material being lower than the coefficient of expansion of the housing material. Other improvements include cooling of the lateral end plates, cooling of the rotors, and the provision of sleeves which serve to fix the position of the rotors on the shafts and which are composed of a material whose coefficient of expansion is lower than that of the rotor material.

Abstract: A method and apparatus for distilling, especially vacuum refining and deodorizing edible oils and fats utilizing sheets of oil driven downwardly in a distiller with a vacuum source at its top. A nozzle includes pressure equalization chambers, cantilever adjustment screws, and a central drag sheet to produce longer lasting and more uniform thin oil sheets to be driven in the distiller. A continuous process deaerates, dehydrates, degums, bleaches, refines, removes tocopherol, deodorizes, and strips peroxides and hydroperoxides from raw oil in a series of isothermal stages utilizing driven sheet distillers. No stripping steam is used except in the stage which strips peroxides and hydro peroxides. The method produces valuable, pure products such as tocopherol and fractionated fatty acids. It is especially efficient in heat exchange and low in waste and pollution producing products.

Abstract: A spiral displacement machine for compressible media is described which has at least one displacement chamber in the form of a spiral-shaped groove arranged in a stationary housing and also has a spiral rib-shaped displacement body associated with each displacement chamber. Each displacement body is on the side of a disc-shaped rotor which is driven eccentrically in a translatory movement relative to the housing. During operation, each peripheral point of the displacement body performs a circular movement bounded by the peripheral walls of the associated displacement chamber. At the edges of the displacement bodies and of the housing walls forming the displacement chambers, sealing strips mounted in spiral grooves engage the adjacent surfaces of the other component of the machine.

Abstract: A screw fluid machine in which the distance between a point on each of bore walls and the axis of a male or female rotor decreases at a normal temperature in the vicinity of a high-pressure port as the point proceeds from the low-pressure side to the high-pressure side.

Abstract: An air-cooled oil-free rotary-type compressor comprises a first air cooling-type air cooler, a backflow preventing valve and a second air cooling-type air cooler respectively disposed in a channel of a discharge gas compressed in a compressor body. The first air cooling-type air cooler and the second air cooling-type air cooler are disposed in a passage of cooling air flow.

Abstract: A cooling water system for a rotary internal combustion engine includes initial direct water cooling for the outer surface of the exhaust manifold with the cooling water directed therefrom to serially interconnected cooling water passages in the various housing elements comprising the engine block. The cooling water passage in each housing element is circumferentially disposed along the peripheral portion of the housing which is directly adjacent the high temperature exhaust and combustion areas of the engine rotor chamber. The cooling system thus supplies water directly to the portions of the engine subject to the highest operating temperatures. The system also includes protection against the formation of hot air or steam pockets and the cooling system is readily adaptable to both single and twin rotor engines.

Abstract: A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

Abstract: Described herein is a method for operating an oil-free screw compressor and an oil-free screw compressor construction, the method including the step of feeding a gas of a temperature Ta to a discharge space in the vicinity of the discharge port of the compressor, the temperature Ta satisfying the relationshipTa.ltoreq.Tl/kwherein Ta is the temperature (.degree.K.) of said feed gas; Tl is the temperature (.degree.K.) of the compressed gas before feeding; and k is a polytropic index number.

Abstract: A fluid cooling system of a rotary piston internal combustion engine of trochoidal type of construction having a housing with one or more trochoidal shaped inner surfaces and having side plates with an eccentric shaft passing therethrough. A triangular piston is mounted upon an eccentric secured to the eccentric shaft and has corners of the triangular piston revolving to have corners of the triangular piston continuously engaged with the inner surfacing and furthermore having the eccentric shaft constructed hollow for cooling of the eccentric bearings and having cooling medium flowing via a by-pass conduit of the main cooling circuit circulation.

Abstract: A multi-section Roots vacuum pump of the reverse flow cooling type with internal flow division arrangement includes a sequence of pump sections, casings for the pump sections including housings for accommodating pairs of rotor therein, inlet passages and outlet passages connected to the casing for pump sections, upper peripheral gas passages connected to the inlet passage formed around an upper portion of the housing, lower peripheral gas passages connected to a supply inlet of reverse flow cooling gas formed around a lower portion of the housing, partition walls between the upper and lower peripheral gas passages, and inter-section walls for separating adjacent pump sections.

Abstract: A liquid or fluid cooled housing of a rotary piston internal combustion engine of trochoidal type of construction consisting of side parts and a dual-arc housing inner surfacing and having an eccentric shaft passing through the side parts. A triangular piston rotates upon an eccentric mounted on the eccentric shaft and corners of the triangular piston are in sliding engagement along the housing inner surfacing. A connection tube is provided supplying cooling medium into the individual housing sections. A series connection of the cooling medium circulation is produced between a first side part in direction of cooling medium flow and a first housing part as well as between a center part and a second housing part respectively having a closure disc installed therewith. Perforations are provided for pressure equalization in the closure discs.

Abstract: A scroll type pump has a fixed scroll and an orbiting scroll engaging therewith, wherein a curve of a wrap of either of the scrolls is offset inwardly or outwardly relative to a set curve so as to prevent formation of a gap between the wraps due to thermal expansion of the scroll wraps.

Abstract: A rotary internal combustion engine has a rotor housing with drilled coolant passages extending generally axially therethrough, a thin wear-resistant liner lines the inner trochoid surface of the rotor housing. A ceramic insert may be used to insulate a top-dead-center region of the inner portion of the rotor housing. Some of the coolant passages may cross each other through a "V-crotch" portion of the housing between the spark plug and pilot injector bores.

Abstract: An external axial rotary piston blower having a housing including a casing part and two side parts of which the casing part encompasses a cylindrical runway surfacing which is formed by two cylinders intersecting each other in a region of an inlet and an outlet and in which two identical pistons having at least one wing portion rotate among each other, such pistons having starting surfaces with a large radius running against a casing runway surfacing and respectively another piston having a starting surface with a small radius running correspondingly against a casing runway surfacing. Shafts of the pistons are offset or shifted in cold condition in a direction of a short housing axis toward the outlet and the housing on the side of the outlet is shorter in axial direction in cold condition than on the side of the inlet.

Abstract: A rotary compressor for helium gas has a cylinder defining a closed space therein, a rotor disposed in the closed space for eccentric rotary motion while making a sliding contact with the inner peripheral surface of the cylinder, and a blade slidably mounted on the cylinder and resiliently projected into the closed space for sliding contact with the rotor so as to divide the closed space into a suction chamber and a discharge chamber. The compressor further has an oil relief passage which is arranged to allow the discharge chamber to communicate with a space outside the discharge chamber in the final stage of the discharging stroke before the crank angle of the compressor reaches an angle corresponding to the position of a discharge port.

Abstract: The engagement parts of the external rotor of a machine having plural fixed internal axes are reinforced by locking screws, which extend radially outwards to the side parts of the external rotor at an acute angle parallel to the longitudinal axis of said engagement parts. The thus prevented bulging of the engagement parts due to centrifugal forces permits high rotational speeds in the case of narrow sealing gaps between the external and internal rotors and with respect to the machine casing.

Abstract: An oilless rotary compressor system including an oilless rotary compressor, a radiator, a precooler, a cooler and a check valve. Heat resulting from a compression by the oilless rotary compressor is carried to the radiator through an aqueous solution of propylene glycol which flows through the oilless rotary compressor and precooler in this order and is dispersed into the atmosphere.

Abstract: A scroll type fluid displacement apparatus with an axial sealing mechanism is disclosed. The compressor includes a pair of scrolls each of which comprises an end plate and a spiral element extending axially from one end surface of the end plate. A groove of uniform depth is formed in the axial end surface of each spiral element and a seal element is disposed within each of the grooves to seal the fluid pockets defined by the scrolls. The axial thickness of the seal element at the center thereof is smaller than the depth of the groove and the axial thickness of the seal element at the outer portion thereof is larger than the depth of the groove. Accordingly, when the compressor is assembled, an axial gap between both scrolls is fixed by the seal element, and the devices can accommodate thermal expansion of the spiral element because of the temperature rise in the fluid upon compression.

Abstract: A housing mantle or casing produced in a compact construction for a rotary piston engine with a trochoidal-shaped dual-arc mantle runway or raceway and sealing strips arranged in corners of a triangular piston rotating upon an eccentric of an eccentric shaft so that the sealing strips slide along the mantle runway. A layer of steel forming the mantle runway and an outer layer of aluminum alloy is cast around the layer of steel. The layer or band of steel forming the runway has openings with radially outwardly bent-open edges which are cast of filled-out with cast metal forming the outer layer as far as to a plane which coincides with a base plane of the steel layer or band forming the mantle runway.

Abstract: The compressor comprises four stages of compression. It has four compression chambers within four, separate compartments removably bolted to a central, supporting, gear housing. In the compression chambers are rotary (rolling) pistons. A pair of parallel, gear-driven shafts journalled in the housing have eccentric pins on ends thereof. The pins intrude into the chambers and rotatably carry the rotary pistons thereon. Conduits traverse the compartments to inject water into the chambers for cooling, sealing, and lubrication of the rotary pistons. Too, the compartments conduct compressed gas therethrough from the compression chambers, and conduct coolant therethrough as well to heat exchange with the compressed gas product.

Abstract: A pair of dry-sealed screw rotors for compressors which includes rotor tooth profiles in which an inter-tooth gap at a profile point on male and female rotor of a normal temperature is determined by an amount of interference due to thermal expansion caused during the operation of the compressors and an amount of minimum safety clearance necessary for the operation. The inter-tooth gap is further determined by a total thickness of seal coatings applied to the peripheral surfaces of the rotors at a profile point at which the thus determined gap is smaller than the total thickness of seal coatings. With the thus shaped rotor teeth, a most preferable seal line is achieved so as to produce an improved compression efficiency.

Abstract: A scroll type hydraulic machine having an improved thrust bearing structure, whereby the thrust bearing is capable of tilting radially and peripherally. The thrust bearing is preferably composed of at least three sectors, and an anti-rotation member is provided between adjacent ones of the sectors. A bearing support is provided, a portion of which has the form of a ball. The thrust bearing is surrounded by an annular portion whose height is substantially the same as that of the thrust bearing.

Abstract: A compressor unit of the type in which a rotary vane compressor draws air from an intake opening and directs it to a pressure tank through a minimum-pressure valve and is self-lubricated by oil supplied by the air pressure itself includes a non-return valve in the intake opening, which maintains the compressor under pressure when it stops. Thus, the internal pressure upstream and downstream of the compressor is balanced instantaneously and the lubricating oil does not get into the compressor, avoiding the consequent danger of damage or breakage upon subsequent starting.

Abstract: A rotary engine has a substantially trochoidal-shaped housing cavity in which a rotor planetates. A cooling system for the engine directs coolant along a single series path consisting of series-connected groups of passages. Some coolant passages in the top-dead-center region are restricted to equalize cooling among various portions of the top-dead-center region.

Abstract: A supercharger for supplying a heat engine of a motor vehicle includes a main body having a working chamber in which rotate at least two bodies continuously sealed along at least one generatrix parallel to the axis of the main body and in which said chamber is in communication with an intake duct and an outlet duct. The main characteristic of this supercharger lies in the fact that it comprises constituent parts made with a relatively rigid supporting structure having an external form provided by moulding material onto the supporting structure.

Abstract: A scroll type fluid displacement apparatus is disclosed which includes a pair of scrolls each having a circular end plate and a spiral element extending from one end surface of the circular end plate. The pair of scrolls are maintained at an angular and radial offset so that both spiral elements interfit to form a plurality of line contacts between their spiral curved surfaces to thereby seal off and define at least one pair of fluid pockets. The fluid pockets are moved by relative orbital motion of the pair of scrolls. At least one of the circular end plates is provided with an anti-wear plate covering the end surface thereof in the area on which an axial end surface of the opposing spiral element slidably contacts. The circular end plate has a depressed portion at the center portion thereof to define an axial clearance between the anti-wear plate and the central portion of the end plate.

Abstract: A hydrostatic machine having a rotor mounted in a housing and having a leakage oil connection, the leakage oil being conducted before discharge to the tank through predetermined housing portions in order to heat the central part of the housing during the start-up phase of the machine.

Abstract: A capacity control device for a compressor used with an air conditioning system for an automotive vehicle and driven by an engine of the automotive vehicle, including flow resistance portions provided in a refrigerant inlet passage and capable of reducing the flow rate of a refrigerant flowing into working chambers of the compressor as the rotational speed of the compressor (or the engine speed) rises, to thereby reduce the volumetric efficiency of the compressor in a high engine speed range.

Abstract: This vane type compressor includes: a main body comprising a cylinder block formed with a bore and end members closing the ends of the bore; a rotor received within the main body in the bore so as to be rotatable about an axis extending in its longitudinal direction, its surface being formed with several slots extending in its longitudinal direction; and several vanes, each slidably fitted into one of the slots with its outer edge bearing against the inside surface of the bore in the main body. The material from which the vanes are formed is a composite material, comprising carbon and a metal including a substantial proportion of aluminum, and further including a substantial quantity of aluminum carbide, which holds the composite material together well and prevents the metal from coming away therefrom. This aluminum carbide may lie between the carbon and the reinforcing metal, and may be in a quantity of from about 1% to about 20%.

Abstract: A rotary vane evacuating pump having two series connected pumping stages is disclosed. Each pumping stage is provided as an exchangeable unit and has a housing which is detachably connected to one face of an interface flange. The housings of the pumping stages are contained in a chamber defined between the interface flange and an outer shell which is detachably mounted thereto. The chamber is filled with water surrounding and contacting the two housings. Each pumping stage is readily dismantled for the purpose of service or replacement.

Abstract: In a rotary vane-type compressor the rotor, the housing and the side plates are made of the same kind of material as one another. A plurality of vane grooves the length of each of which is as long as the thickness of the rotor is provided on the rotor. A set of vanes which is made of a different material than the rotor, more particularly a material the coefficient of thermal expansion of which is larger than that of the rotor, is received in the vane grooves in such manner that the end faces thereof face against the side plate. And the width of the vanes longitudinally of the rotor is determined as follows. The width is slightly less than the thickness of the rotor when the temperature there of is less than normal, but when the temperature becomes high the vane width becomes slightly greater than the thickness of the rotor because of the difference of the coefficients of thermal expansion.

Abstract: A rotary compressor housing is outwardly formed with reinforcing grids in the form of square, diaper or honeycomb. The reinforcing grids allow the intermediate wall portions between the bolted wall portions to thermally expand as much as the bolted wall portions, resulting in that the inner periphery of the center housing always keep its circularity when the inner temperature rises due to an unavoidable compression of air.

Abstract: A rotary engine has a substantially trochoidal-shaped housing cavity in which a rotor planetates. A cooling system for the engine directs coolant along a single series path consisting of series connected groups of passages. Coolant enters near the intake port, passes downwardly and axially through the cooler regions of the engine, then passes upwardly and axially through the hotter regions. By first flowing through the coolest regions, coolant pressure is reduced, thus reducing the saturation temperature of the coolant and thereby enhancing the nucleate boiling heat transfer mechanism which predominates in the high heat flux region of the engine during high power level operation.

Abstract: A single-stage oilless screw compressor system includes a single-stage oilless screw compressor of the type which is capable of operation without requiring oil to be fed to a working chamber of the compressor and which has a pressure ratio (discharge pressure/suction pressure) of over 4, preferably in the range between 7 and 8. The system further includes a precooler located in a gas passage on the discharge side of the compressor, a check valve located on the outlet side of the precooler and a cooler located on the outlet side of the check valve, for supplying a clean gas having no oil incorporated therein which has a pressure of above 4 kgf/cm.sup.2.

Abstract: A scroll type fluid displacement apparatus including a housing, a pair of scroll members each comprising an end plate and a spiral wrap means projecting from one surface of the end plate. Both wrap means are interfitted to make a plurality of line contacts between them, and a driving mechanism including a drive shaft is connected to one of the scroll members to effect orbital motion thereof relative to the other (fixed) scroll member while rotation of the orbiting scroll is prevented. The center portions of the wrap means are made thicker than the remaining portions thereof, the center portions extending substantially from the inner ends of the wrap means outwardly at least throughout the portions thereof which contact one another when the two innermost fluid pockets are merged into a single fluid pocket to form the high pressure space near the center of the scroll members.

Abstract: A scroll type fluid displacement apparatus, for example a refrigerant compressor, includes reinforcing ribs on the rear side of the base plate of the orbiting scroll element to provide rigidity to the base plate. Central and peripheral thrust bearings behind the base plate provide axial restraint for the orbiting scroll element, and one of the thrust bearings is arranged to maintain the fixed and orbital wrap in predetermined angular relationship. A swirling system for the fluid inlet into the scroll apparatus separates liquid from gas in the incoming fluid before it reaches the involute scroll wraps, and the tip edges of the scroll wraps are preformed so that the tip of each scroll wrap tends to expand under exposure to a differential thermal gradient between its inner and outer region to maintain a uniform tip clearance across its entire diameter under operating conditions.

Abstract: A hermetic refrigeration rotary motor-compressor comprising a hermetically sealed pressure tight housing can enclosing a compressor unit comprising a housing having at least two axially spaced walls and rotatable in relation to the housing piston and cylinder-piston journaled on eccentric portions of two oppositely rotatable shafts. The piston and cylinder-piston form movable walls, and axially spaced walls of the housing form stationary walls of at least two compression chambers. The compressor unit may be operated by any suitable prime mover, preferably an electric motor. An intake charge of refrigerant vapor may cool the motor unit and is admitted into the compression chamber through intake ports and discharged through a system of discharge valves into the discharge line.

Abstract: A hermetic refrigeration rotary motor-compressor comprising a hermetically sealed pressure tight housing can enclosing a compressor unit comprising rotary cylinder-piston and piston elements journaled on eccentrics of two oppositely rotatable shafts, and a motor unit for driving the compressor unit having a rotor mounted on one of the compressor unit shafts, with a stator of the motor unit positioned in operative relation to the rotor of the motor unit. The piston and cylinder-piston form moveable walls, and two axially spaced walls form stationary walls of a compression chamber. An intake charge of refrigerant vapor may cool the motor unit and is admitted into the compression chamber through intake ports and discharged through a system of discharge valves into the discharge line.

Abstract: A dynamic cooler apparatus is provided for dynamically cooling molten plastic extrudate while pumping metered amounts of that extrudate to an extrusion die or the like. The dynamic cooler apparatus utilizes bi-helical gears in a gear pump configuration in a housing in which a heat exchange medium is circulated. The heat exchange medium is also circulated internally of the gears so that the gear teeth and the housing act to cool discrete volumes of extrudate from four sides defined by the gear teeth and the internal surface of the housing. The bi-helical gears are driven to minimize loading between the teeth thereof and to permit the teeth to be as small as practical to present more cooling surface for a given cross-section of extrudate and optimize the heat transfer capability of the dynamic cooler apparatus. Provision is also made to use the molten extrudate as a lubricant for the shafts and bearings of the bi-helical gears.

Abstract: The invention comprises a positive fluid displacement apparatus of the scroll-type described as a fluid compressor in the exemplary embodiment. The embodiment has single fixed and movable scroll elements in which the latter describes orbital movement relative to the former to form variable volume pockets therebetween which move from an inlet to an outlet. To accommodate for a difference in thermal expansion between the innermost and outermost zones of the apparatus, the scroll elements are formed with varying thicknesses along the lengths thereof. Accordingly, centrally of the apparatus, whereat an exhaust port is formed, scroll element thicknesses are greatest, the compressed fluid is most dense, and the thermal expansion is least, the elements define close, substantially sealing minimum clearances of a given measure.

Abstract: A scroll compressor for compressing a gas to a high pressure or for use in a refrigeration system such as a refrigerator, freezer, air conditioner or the like, is provided. In the compressor, a compressor unit and its driving motor is enclosed gas-tightly in a casing, and the compressor unit is provided with a backpressure chamber into which is introduced a partially compressed gas so as to press an orbiting scroll member against a stationary scroll member. The compressed gas discharged from the compressor unit is circulated through component parts such as the motor enclosed in the casing before it flows into a next stage outside of the compressor. With the above arrangement, the separation of the orbiting scroll member from the stationary scroll member due to the gas pressure is prevented to thereby attaining a secure axial seal between them, and also the motor is satisfactorily cooled.

Abstract: Apparatus for the generation of compressed air includes a compressor, a motor for driving the compressor, a supply source of liquid lubricant for cooling the compressor, a storage container for the liquid lubricant, devices for separating the lubricant from the compressed air and for cooling the separated lubricant, and devices for controlling and regulating the procedures effected by the apparatus in the generation of the compressed air.

Abstract: A gear-type pump for thermoplastic materials including synthetic and natural polymers or resins, the pump including a housing, intermeshing gears disposed in the housing, the housing having an inlet conduit for directing bulk thermoplastic materials to the gears and an outlet conduit for movement of the material from the gears, and heater structure disposed in the housing and proximate the gears and the inlet and outlet conduits to impart heat to the material as the material flows through the pump.

Abstract: A single-stage oilless screw compressor system includes a single-stage oilless screw compressor of the type which is capable of operation without requiring oil to be fed to a working chamber of the compressor and which has a pressure ratio (discharge pressure/suction pressure) of over 4, preferably in the range between 7 and 8. The system further includes a precooler located in a gas passage on the discharge side of the compressor, a check valve located on the outlet side of the precooler and a cooler located on the outlet side of the check valve, for supplying a clean gas having no oil incorporated therein which has a pressure of above 4 kgf/cm.sup.2.