Abstract: Various multicolor writing tools and methods for applying multiple volatile marking substances one at a time. The tool includes a case member, a cartridge member, a cap member, and an optional actuator member. The case member forms an interior in which is disposed the cartridge member with multiple cartridges each containing one of the marking substances and a tip through which the marking substance is applied. The cap member changes and restores its configuration, while the actuator member changes the configuration and exposes one of the tips selected by an user out of the interior when the tool is in use, and then restores the configuration and encloses all of the tips inside the interior when not in use. Thus, the tool opens the cap member in response to input force without requiring the user to engage in a separate maneuver to remove the cap member.

Abstract: Product applicators that are separable from a product reservoir and that heat a portion of product. A product applicator fitted with an electronic heating element capable of connecting to a low voltage power source. Most of the electric circuitry is incorporated into a circuit subassembly, for example a flexible substrate with printed-on circuit. The preferred heating element is a flexible heater. Heat emanates from the surface of the separable applicator so that the product that is closest to the applicator surface is heated prior to and/or during application.

Abstract: A stretchable device is provided including a base layer; a wipe layer attached to the base layer at a seam and defining an interior space between the wipe and base layers, the interior space having an internal surface; and a pouch positioned within the interior space and attached to one of the seam and the internal surface, the pouch having a top layer, a bottom layer attached to the top layer to form a cavity therebetween, an opening in one of the top and bottom layers, and a pull tab coupled to the pouch and to one of the seam and the internal surface.

Abstract: The present invention relates to a packaging and applicator device comprising: a reservoir containing at least one composition for application; an applicator element that is secured to the reservoir at least during application; an applicator-element holder; and a support for fastening the applicator-element holder on the reservoir, the support including a tubular sheath surrounding the applicator-element holder and the applicator element over at least a fraction of its length, the tubular sheath and the applicator-element holder presenting facing surfaces in contact; at least one hollow longitudinal channel being formed in one of the surfaces, so as to enable the composition coming from the reservoir to flow towards the applicator element.

Abstract: A ring binder mechanism has a resilient polymeric housing. The housing has a central portion and lateral sides extending downwardly along either side of the central portion. A metal ring support is supported between the lateral sides for movement relative to the housing. Each of a plurality of rings includes a first ring member mounted on the ring support for movement therewith to open and close the rings. The housing applies a spring force biasing the ring support toward the open position when the first ring member is proximate its open position and biasing the ring support to the closed position when the first ring member is proximate its closed position. The housing spring force is the only spring force applied to the ring support that moves the ring support.

Abstract: A ring mechanism for retaining loose-leaf pages includes a housing and hinge plates supported by the housing. Rings for retaining the loose-leaf pages are mounted on the hinge plates for movement with the hinge plates between an open and closed position. A lever is mounted on the housing and includes a first portion and a second portion. The second portion is disposed to engage the hinge plates and move the rings from the closed to the open position. The hinge plates are supported by the housing so that at least one of the hinge plates is in continuous engagement with the second portion of the lever when the rings are in the closed position. The at least one hinge plate has an upper surface facing toward the housing and a lower surface facing away from the housing and is in continuous engagement with the second portion of the lever.

Abstract: A modular crankshaft features a connection system between modules that features opposed female receptacles. A pin having opposed beveled ends and hydraulic passages with it is inserted into the opposed receptacles. A pair of seals is disposed on the beveled ends and straddles a hydraulic fluid outlet. The crankshaft wall that defines each receptacle is designed to flex in response to applied hydraulic pressure between the seals on the tapered pin portion. A notch at the base of the receptacle in the crankshaft reduces stress concentration and enables the wall defining the crankshaft receptacle to come back when hydraulic pressure through the pin is removed. The opposed crankshaft receptacles are flanged to allow them to be pulled together over the pin. An interference fit results around the pin after the flanges are mated and the hydraulic pressure is removed.

Abstract: A connection joint (20) is described that is formed by inserting a plastic connector (10) into the end of a silicone tube (14). The connector includes a plurality of barbs (12). A reinforcing agent (16) is placed between each of the barbs (12) of the connector (10). An adhesive (18) is injected between the tube (14), the reinforcing agents (16) and the connector (10). The adhesive (18) is then cured at a predetermined temperature for a predetermined time in order to solidify the connection joint (20).

Abstract: A non-lethal energy absorbing vehicle barrier for decelerating an impacting vehicle includes a first gate member and a second gate member disposed downstream of the first gate member. The first and second gate members are movable from a retracted position in which the first and second gate members are disposed so as not to impede vehicular traffic on a vehicle pathway, to a deployed position in which the first and second gate members are disposed to impede vehicular traffic on the vehicle pathway. The first gate has a height that is lower than a height of the second gate in the deployed position. Both the first and second gate members include at least a pair of deformable energy absorbing members that are deformed in a substantially inboard direction by a deforming member when the first and second gates are deformed from a pre-impact configuration to an impact configuration.

Abstract: The invention relates to a vehicle restraint system provided for delimiting roadways and including guide barriers (1) which are placed next to one another in a detachable manner. Each guide barrier (1) includes a housing-type base body (2) that can be placed upright on the ground and a guide rail (14) arranged above the base body (2). The guide rail (14) and the base body (2) can be coupled together by means of tension rods (19), wherein each tension rod (29) is connected to the guide rail (14) with an upper end (20) and can be tightened at a bottom end (22) in an abutment (23) arranged in the base body (2). The guide rail (14) and the base body (2) are suitably arranged at a vertical distance from one another by spacers (30), with the tension rod (19) extending through the spacers (30).

Abstract: A form for receiving a filler material to create an island is provided. The form is made essentially entirely out of galvannealed steel that is easily paintable. The form has a substantially continuous wall having an outer surface and an inner surface. The wall is made out of a plurality of galvannealed steel wall sections. The wall has a first side and a second side opposite the first side. The inner surface forms an enclosed chamber for receiving the filler material. A first support made out of galvannealed steel is attached to the inner surface of the first side of the wall and a second support made out of galvannealed steel is attached to the inner surface of the second side of the wall. A brace made out of galvannealed steel is disposed between the supports, wherein the brace removably engages the supports.

Abstract: A set of concrete pavers is formed by a plurality of pavers being arranged in a paver row, and a plurality of paver rows being arranged to form a row. A number of parallel, adjacent rows form linear or meandering joints in the end-paver region of the rows when the rows are laid together. At least one section of the upper delimiting surface of the pavers is convexly cambered towards the outside, and projections on the side faces of the pavers form support elements for the adjacent pavers. The support elements, in combination with projections on adjacent pavers, create spaces that act as water-drainage openings in the joint regions. The pavers in each set include not only paving blocks with a length-to-height ratio of less than or equal to 4 but also at least one paving slab with a length-to-height ratio greater than 4.

Abstract: A concrete paving machine which has a main frame and two hydraulic jacking columns at each end of the frame for raising and lowering the machine frame. Crawlers attached to the jacking columns move the paving machine in the travel direction. A paving kit is secured to the main frame and has a rigid center portion. Each terminal kit has an end frame secured to the center portion, an adjustable length support structure between the end frame and the slipform, and a hydraulic actuator. Spacers are interposed between the end frame and the slipform. A finishing pan is provided to finish the concrete surface. All replaceable components of the terminal are constructed and arranged so that they can be manually exchanged be one or two persons without removing the paving kit from the main frame and without needing the help of lifting equipment.

Abstract: A device for generating and maintaining a standing wave face capable of being ridden by an individual. The device includes a container having a base wall and a sidewall and containing a fluid, at least one inlet into the container, and means for imparting a combination of rotational vertical and horizontal velocity to a fluid with-in the container.

Abstract: A socket wrench attachment (SRA) is connected by a circular array of bolts (28) connecting the mounting flange (30) to the rotary output member (22) on a rotary output shaft (20). The shaft (20) is a part of a rotary drive mechanism (12) which is mounted for longitudinal travel along a tower (14).

Abstract: A clamp assembly for securing a vibratory device to a pile comprising a frame, first and second clamp members, and an actuator. The frame is adapted to be secured to the vibratory device. The first clamp member is supported by the frame and comprises a first engaging surface defining peaks and valleys and comprising a first surface layer formed on the peaks and valleys defined by the first engaging surface. The second clamp member is supported by the frame and comprises a second engaging surface defining peaks and valleys and comprising a second surface layer formed on the peaks and valleys defined by the second engaging surface. The actuator member is arranged to displace at least one of the first and second clamp members such that first and second engaging surfaces engage the pile such that the pile is gripped by between first and second clamp members. At least one of the first and second surface layers defines a thickness dimension of at least approximately 0.

Abstract: An erosion control system for reducing shoreline erosion resulting from wave action, runoff and hydrostatic pressure. The system includes a flexible geotextile provided over a shoreline. A plurality of rigid erosion control mats are provided over the flexible geotextile and secured in place by a plurality of anchors secured into the shoreline. The geotextile, erosion control mat and anchors may be adjusted to accommodate shorelines of varying slopes and susceptibility to erosion.

Abstract: Provided herein are systems and methods for use in controlling a translocation process of a pneumatic tube system in order to reduce the amount of energy transferred from the tube system to a pneumatic carrier and, hence, its contents. Generally, these utilities entail identifying and/or reducing forces applied to a pneumatic carrier traveling through a travel path within a pneumatic tube system. The systems and method disposed herein allow for varying the velocity of a pneumatic carrier as it passes through a travel path of the pneumatic system. Such varying of the velocity allows for reducing the total forces applied to the pneumatic carrier during passage through the system. In one arrangement, the power output of a power source connected to a compressor device is altered to vary the velocity of pneumatic carries in the system.

Abstract: A cutting tool that includes an elongate body that has a forward end and a rearward end. The elongate body has a fluted portion that beginning near and extends in a rearward direction from the forward end. The fluted portion has a flute that defines a cutting edge. The flute presents a concave cutting face wherein the concave cutting face is defined by a first radius. The flute further presents a concave core surface adjacent to the concave cutting face wherein the concave core surface is defined by a second radius. The flute presents a convex heel surface adjacent to the concave core surface wherein the convex heel surface is defined by a fourth radius.

Abstract: A cutting tool insert and holder therefore, the drill insert having a helical geometry corresponding to helical flutes in a drill body holder which enable the drill tool assembly to more efficiently remove chips from a hole during operation, the drill insert comprising a drill insert body having a first end opposite a second end, a plurality of helical flutes formed in the drill insert body, a plurality of cutting edges formed at the interfaces of the plurality of helical flutes and the first end of the drill insert body, and an aperture formed in each helical flute.

Abstract: A router has a housing, from the underside of which a tool fitting for a milling tool connected with a drive motor extends and the housing is displaceably accommodated on guide columns for adjusting the milling depth, a device for adjusting the milling depth, which includes a depth adjusting element that is displaceable in the direction of a vertical axis of the router using an adjusting element and that interacts with a stop element, and a device for locking the depth adjusting element. The device for locking the depth adjusting element is integrated in the device for adjusting the milling depth.

Abstract: An engraving machine includes a base with two side panels extending upward from two sides of the base, and a top board is driven horizontally by a motor in the base. A horizontal frame is movably mounted on two rods connected between the two side panels by a motor. A vertical frame is located on a front side of the horizontal frame and is movable along two rods in vertical direction by another motor. The horizontal frame, the vertical frame and the top board are movable along X, Y and Z directions by three independent motors. A chuck is connected to the vertical frame and secures an engraving tool which is driven by a main motor connected between the two side panels. The object to be engraved is secured on the top board and engraved by the engraving tool in X, Y and Z directions.

Abstract: A load restraining apparatus includes a retractable fabric membrane for retaining items in position inside a semi-trailer or shipping container. A membrane carrier is removably fastened to one interior wall of the trailer and a spring-biased retractable membrane is pulled across the width of the trailer and fastened to the other interior wall. A tensioning device tensions the membrane thereby securing the cargo during shipment and preventing shifting inside the shipping container or trailer. The fore and aft adjustability and the vertical adjustability of the load restraining apparatus permit it to effectively restrain cargo of diverse size and shape.

Abstract: A fastening element for mineral constructional components has a shaft (12) provided with a tapping thread (14) extending, at least regionwise, along the shaft (12), and a coating (21) that covers the shaft (12) likewise at least regionwise and that is formed of a polar thermoplast.

Abstract: The invention provides for a retainer for stabilizing a threaded member. The retainer may include a base portion having an opening and an outer perimeter lying in a first plane, the opening having a plurality of elongated sections each extending toward the outer perimeter so as to define in the base portion one or more arms. Each of the aims may have a head section having at least one groove, the head sections being located in a second plane which is parallel to and spaced apart from the first plane. The elongated sections may be symmetrically arranged about an axis. The grooves may be arranged to define at least a portion of a helix. The outer perimeter of the retainer may be circular.

Abstract: A fastener element (16) has a head section (18), a threaded shank section (17) with threads (20) at a pitch and a distal end section (22). A retention device (24) is secured to the distal end section and is engageable with a fastener receiving member (14).

Abstract: A screw includes a shaft, a trumpet-shaped head provided to a base end of the shaft, and a narrow-tip portion formed at a tip end of the shaft. The shaft has different diameters at a small-diameter portion contiguous to the narrow-tip portion and at a large-diameter portion contiguous to the head. Two screw threads are formed on the small-diameter portion and one screw thread is formed on the large-diameter portion. Therefore, a thread portion can be divided into a double-thread portion and a single-thread portion. It is preferable that the screw threads forming the double-thread portion have different heights. The screw is mainly used for fastening a plasterboard to a frame member.

Abstract: In aircraft construction, connection elements for connecting layers of insulating material onto walls are subject to special requirements for ease of installation, weight considerations, and resistance to heat. The invention provides a connection arrangement, in particular for superimposed layers of material, whose function is not impaired under extreme heat. The connection arrangement is comprised by a pin with a head or head arrangement, engaging positions, and a retaining element. The pin, the head or the head arrangement, and retaining element are made up of a skeleton and an outer material where the skeleton is made of a material more resistant to heat than the outer material. Following destruction or removal of the outer material by heat, the remaining skeleton parts of the pin, head part, and retaining element maintain their connections and structure keeping the layers of material in place.

Abstract: A vacuum robot includes an arm portion on which a work is to be disposed under a reduced pressure environment and a motor portion for rotatably driving the arm portion, the vacuum robot being configured to transfer the work by causing a rotational movement of the arm portion by the motor portion. The motor portion comprises a rotor portion connected to the arm portion, a stator portion disposed at an external periphery of the rotor portion, a housing disposed under an atmospheric pressure environment, and a thin cylindrical can disposed in an electromagnetic gap formed between the rotor portion and the stator portion and secured to the housing so that the stator portion is air-tightly encapsulated in a space formed by the housing and the can. The space is maintained in a depressurized state by a seal.

Abstract: A method for loading and unloading rail cars includes at least one car, having a frame and a superstructure, moved into loading and unloading positions. During unloading the car superstructure is lifted off from the frame with lifting devices to an unloading level, and after the lifting operation the superstructure is moved at the unloading level in a transverse direction with respect to a longitudinal plane of the car until the superstructure is seated completely on a loading and unloading face. During loading the superstructure is moved from the loading and unloading face in a transverse direction with respect to the longitudinal plane of the car to above the frame and the superstructure is lowered, by lifting devices, onto the frame located in the loading and unloading positions. The lifting and lowering of the superstructures is carried out by lifting devices that are anchored to the track bed or secured to a platform.

Abstract: A side puller accessory frame for a tow truck having a cab and a truck frame mounts to the truck frame behind the cab. The accessory frame preferably includes two stiff legs, a wire rope winch mounted transverse to the longitudinal axis of the truck that provides pulling force via a removable pivotable center sheave that directs the pulling force to sides or the rear of the truck as desired. The accessory frame may include a removable pivotable side sheave that may mount in a side sheave mounting tube. The side puller accessory frame makes a conventional car carrier with a roll back bed a recovery truck.

Abstract: A lifting apparatus for lifting manufacturing rings is provided. The lifting apparatus includes an attachment part having an opening extending therethrough, and a plurality of elongated legs extending from the attachment part. Each of the elongated legs has a slit disposed therein. A plurality of support rods are movably disposed in the slits. The support rods are pivotable between a lowered position in which each support rod extends from the associated slit and a raised position in which each support rod is disposed within the associated slit. The lifting apparatus further includes an actuating part operably associated with the support rods and for moving the support rods between the raised position and the lowered position.

Abstract: An implement for a machine is provided. The implement has a frame, an operator interface, and a ratchet. The operator interface is pivotally attached to the frame about an axis. The ratchet is mounted about the axis and coupled to the frame and the operator interface.

Abstract: A bucket bale spear bolts together upon a frame, that slips upon the cutting edge of a bucket, and then one bolt secures the frame to the bucket. The frame receives a spear and two balance spikes upon a bracket. A centered tube accepts the spear and secures it with a transverse bolt. The tube provides additional bending resistance for the spear at less weight than a proportional length of spear. The balance spikes also bolt to the frame. The frame, spear, and balance spikes can be shipped and merchandised compactly. At the farm or the ranch, the bucket bale spear assembles readily with hand tools.

Abstract: A handling apparatus can be used to transfer objects from a first location to a second location along a defined path, without the need for a conveyor along the path. Instead, the handling apparatus can be moved along the path by a controllable transport device, such as a robot arm. The handling apparatus can comprise a plurality of unpowered rollers which are selectively rotated by way of a transfer assist mechanism during loading and/or unloading of the objects to be transferred. The transfer assist mechanism can comprise a separate component that can power the rollers directly or indirectly. The transfer assist mechanism can comprise a belt which imparts rotational force to the support rollers via contact in some embodiments, with the amount of force controlled by varying the relative inclination of the support rollers and the transfer assist mechanism.

Abstract: A gas turbine includes a nozzle vane and a sealing unit engaged with the nozzle vane inside a turbine supplied with combustion gases produced by mixing and burning air for combustion and fuel. The nozzle vane and the sealing unit are disposed in a channel of the downward flowing combustion gases on the outlet side of a gas path. A plurality of engagement portions between the sealing unit and the nozzle vane are provided successively from the upstream side toward the downstream side in a direction of flow of the combustion gases, and a downstream one of the plurality of engagement portions has a contact interface formed in a direction across a turbine rotary shaft. A reduction in the thermal efficiency of the gas turbine can be suppressed.

Abstract: A fuel pump includes a housing including an internally-large cylindrical portion coaxial with an internally-small cylindrical portion. A press-inserted portion is press-inserted to the internally-small cylindrical portion. An accommodating cylindrical portion is located in the internally-large cylindrical portion. An accommodating disc portion is opposed to the impeller. A cover is in contact with the accommodating cylindrical portion on the opposite side of the accommodating disc portion. The accommodating disc portion has an impeller-side surface abutted to the accommodating cylindrical portion via an accommodating corner. The outer circumferential periphery of the press-inserted portion has an axial end defining a press-inserted corner on the side of the accommodating cylindrical portion. The accommodating corner is distant from the press-inserted corner for a first distance.

Abstract: A modular fan inlet case includes a center ring, an outer ring, and a plurality of struts each coupled at a first end to the center ring, and at a second end to the outer ring. A plurality of shell members are each configured to be removably coupled to a corresponding strut. Preferably, the plurality of shell members each define a longitudinal groove for being received onto the corresponding strut.

Abstract: A stage for a gas turbine engine, having a plurality of circumferentially spaced apart radially extending aerofoils, includes a plurality of annulus fillers to bridge the spaces between adjacent aerofoils to define an inner wall of a flow annulus through the stage. Each annulus filler has opposing side faces which are spaced circumferentially from the adjacent blades and which correspond in profile therewith, and resilient seal strips each including a stiffener are mounted adjacent the opposing side faces of the annulus fillers to seal the gaps between the annulus fillers and the aerofoils. The stiffeners have three-dimensional curvature.

Abstract: A system and method provide a proactive mechanism to control pitching of the blades of a wind turbine to compensate for rotor imbalance during normal operation by pitching the blades individually or asymmetrically, based on turbulent wind gust measurements in front of the rotor, determined before it reaches the rotor blades.

Abstract: A wall in which there is formed at least one cooling channel, said wall being cooled by cool air flowing in the channel, the channel comprising a hole and a diffusion portion, the hole opening out at one end into the inside surface of the wall, and at its other end into the diffusion portion where it forms an orifice, the diffusion portion flaring around said orifice and opening out into the outside surface of the wall, the diffusion portion having a bottom whose front end is substantially plane, sloping, and extending in front of the orifice, and also having a margin extending behind, round the sides, and in front of the orifice, said margin joining the sides of the front end. A method and an electrode for making such a cooling channel. A turbomachine blade presenting such a wall.

Abstract: A turbine blade with a dual serpentine flow cooling circuit to provide cooling to the airfoil section and to the blade tip section. An aft flowing multiple pass serpentine circuit includes a first leg located adjacent to the leading edge region of the blade and is connected to a leading edge impingement cavity through a row of impingement holes. A showerhead arrangement is connected to the impingement cavity to provide film cooling to the leading edge of the blade. A second aft flowing serpentine circuit is located in the tip region and is connected to the impingement cavity to supply the cooling air to the second serpentine. A row of impingement holes and exit cooling slots is arranged along the trailing edge region and connected to the first serpentine. A trailing edge discharge hole is located in the tip region to discharge cooling air from the second serpentine. The second serpentine includes film cooling holes on the pressure side to discharge film cooling air.

Abstract: The present invention relates to a compressor which secures a sufficient refrigerant inhaling passage so as to minimize a refrigerant inhaling resistance and also to increase lubricating action with respect to a thrust bearing supporting a swash plate, in a structure that refrigerant is inhaled to a cylinder bore through a hollow drive shaft, thereby improving the performance of the compressor.

Abstract: A high pressure radial piston fuel pump is featured having an hydraulic head with two individual radial pumping pistons and associated pumping chambers, annularly spaced around a cavity in the head where a rotating eccentric drive member with associated actuation ring are situated. A rolling interaction is provided between the actuation ring and the inner ends of the pistons for intermittent actuation. Relative rotation is provided between the actuation ring and the drive member. Each piston has a piston bore that has a centerline that intersects the actuation ring but is offset (X) from the drive axis as viewed in cross section perpendicularly to the drive axis and the piston bore centerlines are parallel to each other but offset (Y) from each other as viewed in longitudinal section along the drive axis.

Abstract: A submersible pumping system for use downhole, wherein the system includes a pump, a pump motor, a seal section, a shaft coupling the pump motor to the pump, a bearing assembly for axially retaining the shaft in place, and an electrical insulator for electrically isolating the pump bearing assembly from electrical current leaking from the motor and through the shaft. The electrical insulator can be made from polyetheretherketone, polyimide, polyketone, and mixtures thereof.

Abstract: A fluid fuel pump and its electrically driven brushless motor are located at opposite ends of a common housing.

Abstract: A fluid transporting device is of a writhing type for transporting a fluid continuously. The fluid transporting device comprises a plurality of push pins arranged along a tube and radially on a concentric arc for squeezing a portion of the tube through which the fluid is fed and having elasticity substantially at right angles, and rollers 50 to 53 for pushing those push pins sequentially from the inlet side to the outlet side of the fluid. With this structure, it is possible to provide a thin, small fluid transporting device for continuing a stable flow rate, and a fluid transporter having the fluid transporting device.

Abstract: A pump structure connectable with an aircushion or a bladder. The pump structure includes: a flexible main body defining a valve room in which a relief valve is arranged and a compressible chamber; a one-way valve permitting the fluid to one-way flow into the chamber; and a thin membrane-type check valve. The check valve has a first end and a second end, which are operable between opened position and closed position. The first and second ends respectively communicate with the chamber and an output tube, which is connectable with the aircushion or bladder. The first and second ends of the check valve are respectively positioned in spaces provided by the chamber and the valve room. A substrate board is disposed under the flexible main body. The substrate board has a through hole and a notch formed on positions where the first and second ends of the check valve are formed.

Abstract: A piston cartridge having a piston chamber, an inlet port, an outlet port, and a piston moveable between a first position and a second position. Also, the cartridge includes a first barrier positioned between the piston and the inlet port and a first sealing member moveable between the first barrier and the inlet port, wherein the first sealing member seals the inlet port when positioned adjacent to the inlet port but allows the fluid into the chamber when positioned adjacent to the first barrier. In addition, the cartridge also includes a second barrier positioned adjacent to the outlet port and a second sealing member moveable between the piston and the second barrier, wherein the second sealing member seals the outlet port when positioned adjacent thereto but allows the fluid to pass through the outlet port when positioned adjacent to the second barrier.

Abstract: A single stage root type vacuum pump has a pair of outside air introduction holes formed in the vicinity of a phantom line in an inner wall surface within a range between intersecting points, where the intermediate position that is located between the center of a driving side rotor shaft and the center of a driven side rotor shaft of three-lobe rotors intersects with the intersecting points at which internal circles located on the extended circumferences of the inner wall surface of the casing. The pair of outside air introduction holes formed in symmetrical positions into horizontally long slit shapes parallel to a width direction of the casing. Check valves are fitted to tip end portions of outside air introduction pipes which are respectively connected to outside air communication holes for preventing air from escaping at the time of reverse rotation of the three-lobe rotors.