Abstract: A refrigerant compressor for using HFC 134a as a refrigerant and a refrigerator oil such as polyether type oil, polyester type oil, or the like which is compatible thereto is disclosed. The refrigerant compressor has a iron type substrate with a compound layer mainly made of iron sulfide on sliding portions such as sliding parts and shaft in the compression mechanism. The sliding parts in the compression mechanism are a cylinder and a rotor and a piston which are moving parts. In a rotary type compressor, the sliding parts are a blade and so forth. The hardness of the compound layer mainly made of the aforementioned iron sulfide is large and thereby effectively preventing metals from being contacted and preventing adhesive abrasion which is the primary cause of the abrasion of the sliding portions.

Abstract: An oil groove is formed on the end surface of a rotor of an aluminum alloy for a compressor of a vane type, in an economical manner by a method comprising forming the oil groove of a concave type on the end surface of the rotor slidably moving in contact with a side plate by warm-pressing a die stamp.

Abstract: A hermetic type refrigerant compressor operates using a refrigerant and a refrigerator oil in which the refrigerant is soluble. The refrigerant compressor includes slidable members adapted to slidably move and a compressing mechanism for compressing the refrigerant with the aid of the slidable members in a hermetic casing. The refrigerant, the refrigerator oil and the slidable members are selected and constructed in the following manner. The refrigerant is a 1,1,1,2-tetrafluoroethane or a 1,1-difluoroethane, the refrigerator oil is at least one kind of refrigerator oil selected from a polyalkylene glycol based oil and a polyester based oil, and at least one of the slidable members has a slidable surface which is prepared such that a surface hardened layer having a Vickers hardness of 400 or more and a thickness of 2 microns or more is formed on a substrate of ferrous metallic material, and subsequently, an iron oxide layer composed of Fe.sub.3 O.sub.4 as a main component and having a thickness of 0.

Abstract: The invention proposes in gear ring pumps for reciprocating internal-combustion engines and/or automatic transmissions allowing the hollow gear to run in the hollow gear housing with a play which is large enough for the pronounced fluctuations of the radial position of the crankshaft or input shaft carrying the pinion of the gear ring pump to be taken up thereby and selecting a toothing for the pump such that the effective mounting of the hollow gear on the pinion is achieved. If a correspondingly largeplay is provided between the shaft and the pinion, the hollow gear is mounted with minimum play in the housing. The pinion is then mounted in the hollow gear.

Abstract: A working member of a helical downhole motor can have the form of either a rotor with outer helical teeth or a stator with inner helical teeth. The working member includes separate sections having helical teeth arranged in succession, one after another, and interconnected by rings. Each ring has helical teeth coinciding in pitch and direction with the helical teeth of the sections, and equidistant in profile. This allows automatic orientation of the helical teeth of the sections of the working member.

Abstract: A spacer of a desired thickness sets the clearance between an end face of a fluid displacement device rotor and an end plate of a fluid displacement device housing. Initially the spacer is located on either the end face or the end plate. The end face is then positioned adjacent said end plate. Next, the rotor is axially displaced relative to the housing to a desired position wherein the spacer is in contact with both the end face and the end plate. Finally, the rotor is secured in said desired position.

Abstract: A pivoting vane rotary compressor is disclosed including a housing having a generally cylindrical chamber. A generally cylindrical rotor is mounted eccentrically in the chamber to define about the rotor a main chamber region, which narrows to a constricted chamber region. An intake port is formed in the housing for introducing air into the main chamber region. An exhaust port is formed in the housing for discharging air from the constricted chamber region. At least one pair of vane elements are pivotably mounted to the rotor and extend therefrom into the chamber. The rotor is rotatably driven such that the vane elements engage the cylindrical wall of the chamber and each pair of vane elements defines a compartment that transmits air from the main chamber region to the constricted chamber region, whereby air is compressed and discharged through the exhaust port.

Abstract: A rotary sliding vane pump having vanes fabricated from a carbon/carbon based material that provides improved performance by inhibiting vane wear, chipping or fracture. The advantages provided by carbon/carbon based materials may be further enhanced by impregnating each carbon/carbon sliding vane with a teflon based coating.

Abstract: The seal or pattern between two machine parts has on one of the sealing gap-forming, facing surfaces (5) a plastic layer (1) with closely juxtaposed depressions (8) which have the form of partly cut off voids of an expanded plastic structure. They are formed by the removal of a plastic layer (3) expanded on the machine part, the layer thickness being so uniformly reduced that the voids (4) of the bottom void layer (4) adjacent to the base surface (5) of the machine part are open. This avoids the insulating action of the closed voids of an expanded plastic layer and the latter has a very limited weight, which avoids any risk of the layer being detached or separated due to centrifugal forces. Moreover, in simple manner, a honeycomb-like, open surface structure is obtained, so that there is a labyrinth effect in the sealing gap.

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 rotational speed variable type refrigerant compressor includes a closed vessel in which a refrigerator oil is received and stored, a rotational speed variable type motor mechanism and a compressing mechanism driven by the motor mechanism to compress a refrigerant. The compressing mechanism includes a slidable part which comprises a first slidable member made of a ferrous material with a nitrided layer composed of an iron nitride as a main component formed on the surface thereof and a second slidable member made of a ferrous material with an iron oxide layer composed of Fe.sub.3 O.sub.4 as a main component formed on the surface thereof along which the first slidable member comes in slidable contact with the second slidable member. For example, a shaft is constituted by the first slidable member. In addition, for example, each of the bearings for rotatably supporting the shaft is consituted by the second slidable member.

Abstract: A displacement machine for compressible media includes a stationary housing, and a plurality of disks mounted for eccentric movement within the housing. Each of the disks has two symmetrically disposed spiral displacement bodies that are offset from one another by substantially 180.degree. mounted on at least one side thereof so that the spiral displacement bodies move in an orbital fashion within the housing during operation. The disks are positioned with respect to one another such that each of the spiral displacement bodies intermeshes with another spiral distribution body to define pairs of cooperating spiral displacement bodies. The spiral displacement bodies have a curvature that is dimensioned such that opposed surfaces of cooperating spiral displacement bodies substantially contact one another at at least one sealing line that progresses continuously during operation.

Abstract: A compressor has a cylinder formed of an aluminum alloy, and a moving member slidably received within the cylinder. Hard particles are dispersed in the inner peripheral surface portion of the cylinder. The hard particles are formed of a chemical compound such as a nitride and a carbide. The cylinder is manufactured by preparing a first green compact formed of a mixture of a powdery material for the aluminum alloy and the hard particles and a second green compact formed solely of the powdery material, preparing a billet having an inner layer formed of the first green compact, and an outer layer formed of said second green compact, placing the billet in a preheated state into a container and further heating same therein, and fitting a mandrel through a central bore of the billet and pressurizing the billet to extrude same through a die hole in a die.

Abstract: A helical gear pump having a stator in which the wall thickness of the stator is substantially constant. This reduces heating in dry running conditions and this effect can be improved by providing anti-friction surfaces on both the rotor and stator.

Abstract: A rotary compressor is provided for use in an air conditioner of an automobile. This compressor includes a cylinder having a cylindrical inner wall portion composed of aluminum alloy filled into the pores of a sintered liner composed of iron series metallic fibers, or into the pores of a blister metal liner. With this arrangement, sliding abrasion between the cylindrical inner wall face and the vanes, and deformation thereof by gas compression forces and high temperatures, can be prevented.

Abstract: A helical gear pump is described in which the geometry of the stator and rotor are modified such that the interference is significantly more at the locations of the minor diameter d than the locations of the major diameter D of the rotor. The rotor is preferably plasma coated with modified chromium oxide and the base metal of the rotor is advantageously machined so that in the region of locations of major diameter D, the thickness of the plasma coating is less and, in the region of the locations of minor diameter d, the thickness of the plasma coating is greater than in the remainder of the rotor while allowing the interference to be significantly more at the locations of the minor diameter d than at the locations of the major diameter D.

Abstract: A rotary compressor has a plate-like hollow vane disposed in sliding contact with a rotary piston. The vane has an internal cavity formed by a plurality of bores each having a substantially rectangular cross-section. The corners of each bore are each formed by a curved concave surface of a radius of curvature which is greater than the thicknesses of the outer walls of the vane. The major side surfaces of the vane are in slidable contact with opposing walls of a vane slot and have surface layers each formed of an oxide film consisting mainly of tri-iron tetraoxide (Fe.sub.3 O.sub.4). The film is finished by smoothing processing, thus attaining a smaller friction between the vane major side surfaces and the vane slot walls and suppressing local wear of the vane slot walls.

Abstract: A sliding structure such as a compressor and etc. comprising a member made of an iron base material and another member having a porous ceramic layer slidably contacted with the iron base member, wherein the surface portion of the iron base member has both a porous oxide film containing tri-iron tetroxide as a main constituent, and an oxynitride layer formed under the oxide film.

Abstract: A fluid powered vane motor for operation with a minimum of externally supplied lubrication has a motor chamber made up of a cylinder with an eccentric cylindrical bore and end plates abutting the ends of the cylinder. A rotor with a plurality of axially oriented radial slots on its circumferential surface is supported on bearing means within the chamber. Radially slidable vanes are disposed in the radial slots of the rotor so that they form a moving seal between the rotor surface and the cylinder wall. Pressurized fluid introduced to the motor chamber acts upon the vanes of the rotor and imparts rotary motion thereto. Operation with a limited amount of externally supplied lubrication is accomplished by making end plates of inherently lubricious material such as fiber-reinforced polymeric material, and by coating the innner bore of the cylinder with a soft coating having lubricious properties in contact with the selected vane material.

Abstract: An oilless double rotor, rotary gas compressor with second stage inputs for precompressed gas is described. A compression rotor having at least three lobes which match in intersection to cavities in a counterrotating valving rotor providing an extended sealing surface. The lobes further provide an extended, near-contact surface with the housing with adjacent lobes defining successive compression chambers. Second stage ports are also provided for input of precompressed gas for use with energy recovery systems. A discharge equalization passage is provided in association with a discharge port for efficient gas exhaust.

Abstract: One of male and female rotor elements is coated with a coating which is different in hardness from the other uncoated element. Even when the rotor elements come to contact with each other during the operation due to thermal expansion or the like, because of the difference in hardness between the coating and the other uncoated element, either of them which has a less degree of hardness is scraped off. As a result, accident due to contact between the male and female rotor elements can be prevented and the screw rotor can be operated with an optimum clearance between the elements.

Abstract: Vane type positive displacement pump includes three separate vane type pump units on a single shaft, with spacers between the middle pump unit and both end pump units for axially positioning the pump vanes for the middle pump unit at both ends and axially positioning the pump vanes for the two end pump units at one end. The shaft has reduced diameter journal portions adjacent opposite ends of the barrel portion for the middle pump unit on which the spacers are mounted. Also, the outer diameter of the barrel portions for the two end pump units corresponds to the outer diameter of the journal portions for the spacers. At the other end of the end pump units are end bearings for axially positioning the vanes for the end pump units at such other ends.

Abstract: The instant invention relates to a displacement-type rotary system steam-turbine engine that among other mainly functions as a displacing-type steam engine. Through the partial utilization of the kinetic energy generated by the impinging steam molecules upon the rotor blades said invention functions additionally similar to a radial flow turbine.

Abstract: A vane compressor in which a cylinder block, front and rear side blocks, a rotor, and vanes are formed of an aluminum-based alloy, and at least one of the component parts are coated with Ni electroless composite plating layers having polytetrafluoroethylene (PTFE) dispersed therein. The vane compressor further includes a capacity-controlling plate interposed between the rear side block and the rotor, which is formed of the aluminum-based alloy and coated with the Ni electroless composite plating layer having PTFE dispersed therein.

Abstract: A vane for a rotary fluid pump and a method for producing the vane are disclosed. The vane has a base vane body and an overlaid welding layer which functions as a sliding layer. The sliding layer is formed by using alloy powders and applying plasma arc to the end face of the base vane body. The alloy powders have high wear resistivity high resistance to thermal seizure and high corrosion resistance. During application of the plasma arc, the alloy powders are supplied, so that first and second layers are presented in the sliding layer. The first layer which is an inner layer is formed of a mixture of a material of the base vane body and the material of the alloy powders, and the second layer which is an outer layer is formed of the alloy powder material only.

Abstract: A rotor for a rotary screw machine having helical lobes and intermediate grooves, the rotor having a core including a shaft 1 of a first material and a rotor body 2 of a second material mounted on the shaft. The surface of the rotor is coated with a plastic layer 3.

Abstract: A portable abrading or polishing tool including a body structure containing an air motor which drives a head carrying an abrading or polishing element to abrade or polish a work surface. The motor has a housing containing a chamber within which a rotor turns, with an essentially vertical shaft of the motor projecting downwardly through a bottom wall of the housing and operatively connected to the head to drive it. A wear plate is located vertically between the rotor and the bottom wall of the housing and is formed of a material harder than the rotor or housing, and contains an opening through which the shaft projects downwardly in closely fitting but non-contacting relation to minimize downward escape of air from the chamber along the shaft and protect a bearing carried by the bottom wall of the housing against loss of lubricant by the pressure of escaping air.

Abstract: A dual-shaft machine comprising a housing, two pistons rotatably mounted in the housing leaving a cold play spacing between one another and said housing, and a coating provided on either the housing or the pistons, or both, to reduce the cold play spacing to that required by the intended field of use of the machine.

Abstract: A sliding member of an iron-based non-porous material, such as vane, of a rotary compressor has a sliding surface processed by a surface treatment in which the surface is subjected to oxidizing and nitriding to form an oxidized and nitrided layer thereon. The surface is then subjected to a steam-treatment in which water is caused to react with components of the oxidized and nitrided layer to form a layer of oxidized iron of a porous network structure disposed outwardly of the oxidized and nitrided layer. The oxidized iron layer is composed mainly of tri-iron tetroxide and softer than the oxidized and nitrided layer.

Abstract: A rotary pump having an eccentric rotor disposed in a cylindrical housing is provided with a pair of cylindrical roller pistons disposed in opposed recesses in the rotor for rolling engagement with the internal surface of the housing. A pair of bearing rings having radially inwardly projecting ribs are located at opposite ends of the housing with the ribs disposed in engagement with complimentary grooves formed in the external surface of the rotor and in the external surfaces of each roller to positively locate the rollers within the recesses. A plurality of bearing support members are provided having semi-circular cradle portions engaging the grooves in the rollers and parallel leg portions extending through parallel bores in the housing. Interconnecting rods are provided between the legs of opposed bearing support members to maintain the rollers in positive engagement with the internal surface of the housing at all times.

Abstract: The portable medical suction device of the preferred embodiment of the present invention comprises a disposable suction component including a suction tube bonded to the inlet of a plastic flow-through rotary vane pump, a collection tube bonded to the pump outlet and a flexible reservoir bag bonded to the collection tube and having a hydrophobic vent, adapted to be economically disposed of after a single use without the necessity of cleaning the components of the device that contact the aspirate. The rotary vane pump of the disposable component is designed for ready operable coupling and decoupling to the output of an electric motor. The motor is removably mounted in a support frame. The reservoir bag is also gathered within the support frame, having a first volume capacity when so gathered and a second larger volume capacity when unfolded through an opening at one end of the support frame.

Abstract: A scroll type compressor is disclosed which includes a housing with an inner chamber and fluid inlet and outlet ports connected to the inner chamber. A fixed scroll, which is mounted within the housing, has an end plate from which a first spiral wrap extends. An orbiting scroll also is mounted within the housing for orbital motion with respect to the fixed scroll. The orbiting scroll has an end plate from which a second spiral wrap extends; and the first and second wraps interfit to define at least one pair of sealed off fluid pockets. The end plate of the fixed scroll partitions the inner chamber of the housing into a suction chamber and rear chamber. The end plate of the fixed scroll has at least one pair of holes for adjusting the displacement of the compressor. A control mechanism selectively controls fluid communication through the holes. The axial end surface of the second wrap is provided with a seal element which forms an axial seal between the second wrap and the end plate of the fixed scroll.

Abstract: In a positive displacement machine, a rotor has screw grooves in which pressure chambers are variably limited, at one end, by teeth of a plastic pinion which is the front element of a composite pinion meshing with the grooves. A metal backing pinion supports the plastic pinion. The metal pinion and plastic pinion are rotatable with respect to each other about the axis of rotation of the composite pinion, in conjunction with a deformation of a resilient angular coupling provided between them. This coupling is a metal blade at least partly surrounding the backing pinion shaft between the plastic pinion and the backing pinion, in a groove of the backing pinion. One end of the blade is secured to the plastic pinion, the other end of the blade is secured to the backing pinion. Several embodiments of the blade are disclosed.

Abstract: A displacement machine for fluids, having a displacement chamber, arranged in the manner of a groove in a fixed casing, running approximately spirally from an inlet to an outlet and spanning more than 360.degree., into which chamber a likewise essentially spiral displacement body engages, which is held eccentrically drivably in such a way so as to execute a circular movement limited by the peripheral walls of the displacement chamber, the radii of curvature of the displacement body and the said peripheral walls being dimensioned such that, during its circulating, twist-free movement, the displacement body at least virtually touches the inner and outer peripheral walls at a continuously progressing sealing line.

Abstract: The stator comprises a rigid tubular casing and an elastic lining which is tightly enclosed by the casing and symmetrical with respect to the longitudinal center axis of the stator. The inner surface of the lining forms a multiple thread and, in cross section, consists of a number of sections near the axis equal to the number of courses of the thread and an equally great number of concave arcs. The lining has a minimum thickness each at the concave arcs and a maximum thickness each near at least two of the transitions between the sections near the axis and the concave arcs.

Abstract: A rotary vane compressor or vacuum pump having an extended service life in which the rotor housing is composed of cast iron, the rotor of either cast iron or powder metallurgy materials, and the associated adjacent surfaces which form the rotor chamber are coated with a material having the characteristics of plastic with respect to friction and abrasion resistance.

Abstract: A starter arrangement for an engine includes a fluid actuated rotary vane motor which is adapted to engage an associated engine. The rotary motor has a plurality of blades or vanes with each of the blades being made from a fiber reinforced plastic material to reduce friction. A sleeve, in which the rotary motor is positioned, has on its inner surface a hard metallic coating to reduce friction. A relay valve member selectively provides a pressurized operating fluid to the rotary motor. The blade material and the sleeve inner surface coating cooperate to enable the vane motor, when it is actuated by the relay valve member, to rotate in the sleeve with a minimum of friction thereby obviating the need for a lubricating agent.

Abstract: A gap seal formed between surfaces cooperating with each other such that operation free of engagement between the cooperating rotor and housing parts with respect to each other at relative speeds occurs subject to a roughened light-metal surface of one part cooperating with a covering of foamed synthetic material on the other part so as to assure gap seal therebetween rather than having any metal-to-metal and/or foamed-material to foamed-material interengagement. The foamed synthetic material covering of a surface preferably is made of polyurethane and the light-metal surface is made of aluminum roughened by sandblasting or etching. The lightweight metal part can have cavities and recess spaces therein to be filled with foamed material as well as other fins, ribs, and anchoring provision for holding the foamed synthetic material bodies in place.

Abstract: In a rotary piston engine which can be produced by simple manufacturing techniques and which has an outer and an inner rotor which rotate in a housing about different axes of rotation, wherein strip-like projections on inwardly extending engagement members generate the contour of the piston of the inner rotor, whereby a well-defined contact seal can be realized in use, the projections have two sealing corners adjacent to but spaced from one another in the direction of rotation of the outer rotor.

Abstract: A reversible, self-priming rotary pump has a housing with a stator of elastomeric material which is softer than the elastomeric material of the rotor on a cam on shaft. The inlet and exhaust ports are separated by a lobe received in a recess in the stator. As the shaft is rotated, the rotor orbits within the stator to pump the fluid between the inlet and exhaust ports, the stator being at least partially compressed along the line of contact with the rotor to form an efficient seal therebetween.

Abstract: A scroll type fluid displacement apparatus is disclosed in which a pair of scrolls interfit at an angular and radial offset, each scroll including a circular end plate and a spiral element. The outer wall surface of each spiral element, which extends from an outer terminal end of the spiral element to the point of contact with the outer terminal end of the opposed spiral element at the orbital position where the sealed off fluid pockets are initially formed, is a rough unfinished surface. Accordingly, the time for manufacturing each spiral element is reduced and waste of material which is produced when the scroll surfaces are finished by turning is decreased.

Abstract: The invention comprises a rotary pump with sliding vanes with a self-lubricating solid coating covering the exterior end facing surfaces of the rotor and end facing surfaces of air transfer end plates. Additionally disclosed herein is a rotary pump with sliding vanes with a pair of bushings centrally located in the rotor with the internal bearing facing surfaces of the bushings covered with a self-lubricating solid coating.

Abstract: A rotary vane pump having a metallic rotor, rotatably positioned within an ellipsoidal cavity, a pair of stationary wear plates on the sides of the cavity, the rotor having a plurality of radial slots each of which contain a carbon composite vane riding against the ellipsoidal cavity in reciprocal motion to define variable volume pumping chambers and a pair of carbon composite rotor side plates each being positioned between one side of the rotor and the stationary wear plates, each of the rotor side plates having a similar pattern of congruent radial slots to that of the rotor, the vanes having sufficient width to extend into the slots of both side plates to drive the side plates with the rotor during operating.

Abstract: A compressor has stationary and orbiting scroll members formed thereon with spiral wraps engaged with each other to define compression chambers which, when the orbiting scroll member is moved relative to the stationary scroll member, are radially inwardly moved while decreasing their volumes. Each scroll member is composed of a metallic base scroll member having a spiral wrap formed on one side and a coating layer of a resin compound formed on the said side of the scroll member, including the surfaces of the wrap. The coating layer is molded by placing the base scroll member in a mold cavity with a space left between the said side of the base scroll member and a mold part and by injecting the resin compound into the space.

Abstract: A vane pump in which an engaging portion in engagement with vanes to restrain the protrusion of the vanes to a given amount is provided on the inner surface of an end wall of a housing, the vanes being made of a material having a relatively high brittleness, the housing having an inner peripheral surface finished into a rough surface so as to restrain the sliding resistance of the vanes resulting from rotation thereof.

Abstract: A single rotary pump is provided with a driven valve having outer curved faces and inner curved recesses along the major axis thereof, a rotary piston having vanes between which there are semi-ellipses having raised portions therebetween, said valve being driven by an external source to cause rotation of said piston whereby liquid under pressure flows from an inlet of the pump to an outlet of the pump.

Abstract: A steering power-assistance pump of vane type includes a combined flow control and pressure relief valve. When the steering valve of the steering arrangement shuts off the flow of oil, the output of the pump is converted into heat within the pump which accordingly suffers a substantial rise in temperature. The rotor of the pump and the cam ring with which the rotor vanes co-operate are combined with a pressure plate and a wear plate on respective sides of the rotor to form a unit which is displaceable in the axial direction of the pump against the force of a compressible sealing means for sealing off inlet ducts relative to a pressure chamber behind the pressure plate. The unit is thus displaced against the force of the compressible sealing means, as a result of thermally induced deformation of the housing portions of the pump. The wear and pressure plates have coatings of bearing metal on their surfaces which co-operate with the rotor, to provide better anti-friction properties.

Abstract: A Roots type pump comprising a pair of mating lobed rotors which are supported by rotor shafts, respectively. Each rotor is fixed to the corresponding rotor shaft by a pin forcibly inserted in a through hole provided through the rotor and rotor shaft. The outer surface of each rotor is surrounded by a coating layer of plastic material, at which the through hole has end openings having cross sectional dimensions greater than that of the substantial part of the through hole.

Abstract: A press for the preparation of raw plastic material blanks is described. It has a feed device connected to a rotor housing in which a circular rotor is eccentrically supported for the generation of pressure and the transport of the material. Rotor housing and rotor form a tapering channel. The circular rotor has at least one axially extending material transport ridge forcibly guided along a guide rail located in the rotor housing. At its smaller end the tapering channel forms an extrusion gap which opens into an outlet opening for the plastic material, to which a nozzle is attached.

Abstract: A starter arrangement for an engine includes a fluid actuated rotary vane motor which is adapted to engage an associated engine. The rotary motor has a plurality of blades or vanes with each of the blades being made from a fiber reinforced plastic material to reduce friction. A sleeve, in which the rotary motor is positioned, has on its inner surface a hard metallic coating to reduce friction. A relay valve member selectively provides a pressurized operating fluid to the rotary motor. The blade material and the sleeve inner surface coating cooperate to enable the vane motor, when it is actuated by the relay valve member, to rotate in the sleeve with a minimum of friction thereby obviating the need for a lubricating agent.