Abstract: Disclosed is a novel transfer conveyor for transporting material from a feed point to an input section of a main conveyor. The transfer conveyor comprises a feed end, a discharge end, and a means for conveying material from the feed end to the discharge end. A connector is provided for detachably and rotatably connecting the transfer conveyor to the main conveyor such that the feed end of the transfer conveyor may be moved about the input section of the main conveyor while maintaining the flow of material from the discharge end of the transfer conveyor into an input section of the main conveyor. The transfer conveyor may be provided with a nozzle portion on the discharge end thereof to which the connector is attached.

Abstract: A gravity conveyor includes one or more zones with each zone having at least one brake associated therewith. A controller turns the brakes on for each zone according to various programmable conditions. The downstream-most zone may have its brakes turned on whenever a package is present at the end of the conveyor. Any of the zones may have their brakes turned on in a pulsed manner. The zones may also have their brakes turned on in other situations, such as simultaneous blockage of that zone with another zone, the initial sensing of the leading edge of an article, as well as in other situations.

Abstract: A roller insert assembly is installed within a cooling bed plate including a plurality of spaced apart longitudinal members and a plurality of spaced apart transverse members which collectively define an array of pockets therebetween. The assembly includes a roller pivotal about a roller axis. An axle cooperates with the roller and is coaxially aligned with the roller axis. The axle has two end portions located at opposed axial ends of the roller. The assembly also includes a pair of bearing supports sized to fit within a pair of transversely aligned U-shaped cut-out notches. The U-shaped notches are formed in a pair of spaced apart longitudinal members. A bearing is mounted within each bearing support for pivotally engaging the axle end portions. The roller insert assembly is designed to orient an upper portion of the roller at a select height above the cooling bed plate to provide rolling support to a heated planar object positioned thereon during cooling.

Abstract: The subject matter of the present invention is a brake roller (30, 40, 50, 60) for a roller conveyor (1) with a cylindrical tube (32, 42, 52, 62), said tube being rotatably carried on an axle (31, 41, 51, 61) that is resting on supports (2), said cylindrical tube being provided with a braking device, said braking device being provided with means for producing electromagnetic fields for slowing down the cylindrical tube (32, 42, 52, 62).

Abstract: An elongated cylindrical roller tube is rotatably supported between frame members by a pair of bearing units secured to opposite end portions of the tube. Each bearing unit includes a tubular shaft supporting a hexagonal stub axle for axial movement between an outwardly projecting position engaging a frame member and an inwardly retracted position against the bias of a spring member connected to the shaft. An anti-friction bearing is mounted on the tubular shaft and is retained within the roller tube by an annular adapter. An annular dust cover projects radially outwardly from the tubular shaft to protect the bearing. Some parts are molded of an electrically conductive plastics material, and each hexagonal stub axle has a slightly resilient outer surface, a rigid core pin and a tapered and twisted outer tip portion.

Abstract: A pulley with pulley lagging, a pulley, pulley lagging and belt system and method are provided. The pulley has an outer surface with a length and a circumference. A hook and loop fastener strip is provided having one of a loop or a hook surface section and a back surface. The hook and loop fastener strip has a first tapered end with a first cutline edge and a second tapered end with a second cutline edge. The hook and loop fastener strip back surface is bonded to the pulley element outer surface with the strip spiral wrapped with the first cutline edge having a length substantially equal to the circumference and positioned substantially at an edge of the pulley element and with the second cutline edge having a length substantially equal to the circumference and positioned substantially at another edge of said pulley element.

Abstract: A conveyor 10 is provided having a frame 12 with a first side and a second side. At least one extensible and retractable support 36 extends between the first and second sides such that a distance between the first and second sides is selectively adjustable. At least one conveyor tack 76 is removably carried on the frame 12.

Abstract: A conveyor roller assembly comprising a supporting bracket through which the roller assembly can be fixed in use, a hollow, generally cylindrical roller shell supported for rotation about its longitudinal axis on said bracket, an electrical generator housed within said roller shell and driven thereby by rotation of the shell to produce an electrical output, a brake within said roller shell and operable to brake rotation of said shell relative to said bracket, a speed sensor within said shell for sensing the speed of rotation of said shell relative to said bracket, and, an actuator powered by the electrical output of said generator when said speed sensor detects that the speed of rotation of said shell relative to said bracket exceeds a predetermined value, to effect operation of said brake to brake rotation of the shell.

Abstract: The invention relates to a mounting and dismounting mechanism for a straightening or calibrating roller (2) rotatable about a spindle (1) and provided with a circular groove (13). The spindle (1) has its cavity (4) fitted with a pusher (9), having a tapered thrust face (9a, 9b) which shifts, as a result of the force of a spring (10), a holder element (8) from its release position to its clamping position. The holder element (8) is located in an opening present in a wall (3) of the cylinder (4). A plunger (11), associated with the pusher (9), can be used for moving the pusher against the force of the spring (10) to a position in which the holder element (8) is capable of shifting from its clamping position to its release position in which the roller is removable from the spindle (1) or mountable onto the spindle.

Abstract: A conveyor roller includes a generally cylindrical roller tube and a pair of stub shafts rotatably mounted in each end thereof. At least one of the stub shafts is mounted for axial movement between an extended position and a retracted position. When in the extended position, the stub shafts on each end of the conveyor engage respective mounting holes in the conveyor frame. To insert the conveyor roller in the conveyor frame, the movable stub shaft is moved to a retracted position while the roller is lowered into the conveyor frame. When the stub shaft aligns with the mounting holes in the conveyor frame, the stub shaft is urged back to the extended position by a biasing member to engage the mounting hole in the conveyor frame.

Abstract: A roller track assembly includes an outer channel member and inner channel member having rollers attached and which vertically displaces in the channel of the outer channel member in response to inflation of an inflatable air bag in the channel of the outer channel member. A top plate is quick release attached to the outer channel member by a detent arrangement and covers the outer channel member and inner channel member. The top plate has openings through which rollers rotatably secured to the inner channel member selectively protrude in response to inflation of the air bag. Sealing covers prevent debris entering top plate openings from falling into the interface regions between the inner and outer channel members.

Abstract: Freewheel flow track systems for transporting pallets and/or cartons in heavy-duty pallet and carton flow applications are disclosed. According to certain embodiments of the invention, a flow track system comprising multiple longitudinally extending, parallel track sub-assemblies is disclosed. The track sub-assemblies each comprise multiple wheel assemblies mounted to a track frame and arranged in a row extending from an entrance end of the track assembly to an exit end of the track assembly. Each wheel assembly comprises an axle and a polycarbonate resin wheel rotatably mounted on the axle. A lubricant coating is fixed to and bonded with the axle. The wheel is constructed from a polycarbonate-based resin that is impregnated with a lubricant for providing lifetime lubrication to the wheels. The wheel includes a hub, a rim concentric with the hub, a web connecting the hub to the rim, and ribs connecting the hub to the rim through the web.

Abstract: A roll-forming unit of a curved glass manufacturing apparatus includes a cooperating pair of upper and lower forming roll mechanisms. Each mechanism includes a forming roll having a resilient rod covered with a cover member except opposite end portions thereof, a pair of support members rotatably supporting the opposite end portions of the resilient rod while allowing the resilient rod to tilt about said support members, a bending unit coupled with at least one of the opposite end portions of the resilient rod for applying to the one end portion an external force tending to flex the forming roll into either an upwardly arched configuration or a downwardly arched configuration, and at least one backup roller unit being in rolling engagement with the forming roll to maintain the arched configuration of the forming roll.

Abstract: A chain of rolling elements comprises a plurality of rolling elements and an elongate carrier belt with a plurality of recesses for receiving the rolling elements, a plurality of retainers for retaining the rolling elements received in the recesses and at least one elongate flexible element for connecting the retainers. The carrier belt comprises two lateral edge portions and a central portion connecting them, the retainers being connected to the at least one flexible element in the lateral edge regions of the carrier belt. Separate retainers are associated with successive rolling elements, at least one retainer associated with each rolling element being provided on the at least one flexible element in the longitudinal direction thereof before and after each rolling element.

Abstract: A roll assembly is disclosed having a roll, a carrier strip secured to the roll, and a replaceable cover strip adhesively bonded to the carrier strip. Upon removal of the cover strip, the adhesive bond causes a portion of the carrier strip to be pulled away with the cover strip. A replacement cover strip can then be adhesively bonded to the newly exposed surface of the carrier strip.

Abstract: A unidirectional conveyor roller for use in a pre-existing conveyor roller system includes a cylindrical roller body supported on a shaft by ball bearing assemblies. A roller clutch bearing between the roller body and the shaft limits relative rotation to a single direction. An internal spring mechanism allows the shaft to be temporarily retracted for facilitating installation on the conveyor roller system.

Abstract: A vacuum chamber for flat substrates features transport rollers for transport of the substrates. These transport rollers are held from the sides in bearings and are additionally braced between the bearings by at least one middle bearing. These middle bearings are each located on a plunger which is guided hermetically through an opening in the bottom of the vacuum chamber and is braced against a support underneath the bottom.

Abstract: A refurbishable conveyor system roller having an inner cylinder, an outer cylinder concentrically mounted over said inner cylinder, couplings at each end of said inner cylinder, an end cap at each end joined to said inner cylinder by the couplings, a bearing assembly removably mounted between said end caps and said inner cylinder and a steel rod passing through said roller for mounting or engaging said roller to a corresponding conveyor system.

Abstract: A roller track is provided, for support thereon of goods, which includes a pair of profile members, each profile member having a length extent and a plurality of holes spaced from one another along its length extent and a plurality of rollers. The rollers are mountable in rotatable dispositions in which the rollers extend transversely between and are supported by the pair of profile members, each roller having at least one borehole which is at a respective axial end of the roller and extends in the direction of the roller axis. The roller track includes a plurality of retaining elements for retaining the rollers in their rotatable dispositions on the pair of profile members. Each retaining element is releasably mountable on one of the profile members and includes at least one axle oriented to extend perpendicularly to the length extent of the profile member upon mounting of the retaining element on the profile member.

Abstract: A transporting roller is provided. The transporting roller includes two parallel spaced apart side flanges and a central part positioned between the flanges. The flanges and the central part have corresponding pass-through openings. The central part also includes at least one annular circumferential part rotatable with respect to the flanges when the circumferential part contacts a conveying path.

Abstract: A conveyor roller for motorized conveyors including a lateral friction torque limiting mechanism to drive a roller tube via a rotation driving element. The torque limiting mechanism includes a first friction surface associated with the roller tube and a second friction surface associated with the drive element. The second friction surface is made of a magnetic material. The first and second friction surfaces are applied one against the other through a magnetic field generated by permanent magnets. When the force required to rotate the roller tube is higher than the frictional force between the first and second friction surfaces, slippage will occur between the first and second friction surfaces, stopping the rotation of the roller. The drive element includes ventilation channels to thereby cool the friction surfaces.

Abstract: A roll belt conveyor having a shaft that supports, adjacent to both ends, the inner ring of a rolling bearing whose outer ring carries a cylindrical tube encompassing the shaft, there being provided a seal on the outside of each rolling bearing, the roll comprising a ring-shaped bearing housing that presents an external peripheral surface, encasable through elastic deformation, into a superficial internal recess of the cylindrical tube, so as to lock, radially and axially to this the ring-shaped bearing housing, and retaining the adjacent rolling bearing against radial and axial displacements, at least in the inward direction of the roll.

Abstract: A conveyor frame comprises a support frame, a rolling shaft, and a ball frame. The support frame is provided at both ends of the longitudinal axis thereof with a folded plate which is provided with a locating hole. The folded plates are provided with an annular protrusion. The rolling shaft is pivoted between the two locating holes of the folded plates. The ball frame has a long body which is provided in one side thereof with a plurality of balls and at both ends thereof with a long cover plate. The long cover plate is provided with a long hole extending along the direction of the longitudinal axis thereof. The long body is further provided at both ends thereof with a shoulder of a predetermined length and extending along the longitudinal side of the cover plate.

Abstract: A bearing structure has first and second support members in which first and second stepped small-diameter portions of drive and nip rollers are rotatably mounted by bearings. The first and second support members are disposed in respective first and second holes defined in a side wall and have respective first and second inner engaging teeth and respective first and second outer engaging flanges which are held against respective opposite surfaces of the side wall to retain the first and second support members on the side wall against removal. The first and second support members thus firmly retained in position on the side wall can reliably bear thrust forces from the drive roller and the nip roller. The drive roller and the nip roller and the bearings can be assembled and serviced with ease.

Abstract: In a device for coating of spacer frames (2) for insulated glass panes, there are nozzles on either side of conveyor (1) from which adhesive or sealant is applied to side surfaces (4) of spacer frame (2). Above conveyor (1) there are pressure rollers (10) which press spacer frame (2) against conveyor belt (1) Pressure rollers (10) engage spacer frame (2) in the area of the side edges of inside surface (6) of hollow section (5) which is forming. In this way a frictional connection between conveyor belt (1) and spacer frame (2) is effected and the leg of spacer frame (2) which lies on conveyor belt (1) is guided laterally. Pressure rollers (10) need not be swivelled up when staves (10) move past pressure rollers (10) when spacer frame (2) provided with staves (15) is being coated.

Abstract: An elongated cylindrical roller tube is rotatably supported between frame members by a pair of bearing units secured to opposite end portions of the tube. Each bearing unit includes a tubular shaft supporting a hexagonal stub axle for axial movement between an outwardly projecting position engaging a frame member and an inwardly retracted position against the bias of a spring member connected to the shaft. An anti-friction bearing is mounted on the tubular shaft and is retained within the roller tube by an annular adapter. An annular dust cover projects radially outwardly from the tubular shaft to protect the bearing. Some parts are molded of an electrically conductive plastics material, and each hexagonal stub axle has a slightly resilient outer surface, a rigid core pin and a tapered and twisted outer tip portion.

Abstract: A conveyor-belt roller assembly secured inside a conveyor-belt roller and onto an inner shaft, preferably used in conveyor-belts used for carrying high loads of material in hazardous environments. The conveyor-belt roller assembly has a stationary anti-lock shield which protects the rotating exterior surface from coming into contact with the outside elements for example debris and machinery. A dust shield is also position aft of the anti-lock shield to prevent the penetration of small particles and dust into the inner workings of the conveyor-belt roller assembly. The conveyor-belt roller assembly also has deep rings in the load-bearing portion for thermal expansion and contraction as well as heat dissipation. Bridging ribs are positioned across the deep rings to greatly increase the strength and therefore load-baring capacity of the conveyor-belt roller assembly. A tapered labyrinth seal is used so that it can be press locked into position making installation quicker and easier.

Abstract: A conveyor roller includes a generally cylindrical roller tube and a pair of stub shafts rotatably mounted in each end thereof. At least one of the stub shafts is mounted for axial movement between an extended position and a retracted position. When in the extended position, the stub shafts on each end of the conveyor engage respective mounting holes in the conveyor frame. To insert the conveyor roller in the conveyor frame, the movable stub shaft is moved to a retracted position while the roller is lowered into the conveyor frame. When the stub shaft aligns with the mounting holes in the conveyor frame, the stub shaft is urged back to the extended position by a biasing member to engage the mounting hole in the conveyor frame.

Abstract: A chute for supporting and facilitating transport of packages has a skived PTFE film adhesively bonded to a transport substrate. A pressure sensitive adhesive is pre-formed on and bonded to an entire surface of a first side of said skived PTFE film. Prior to installation, a release liner covers the adhesive. After the release liner is removed, the skived PTFE film with the pre-formed adhesive is attached to the substrate through the application of pressure to an opposite side of the film. The exposed opposite side of the film provides a lubricious transport surface on which packages move continuously without build-up. The film has a thickness which accommodates significant abrasion wear over time while continuing to provide a lubricious transport surface. The skived PTFE film may contain a carbon filler to prevent static electric build-up. The film can be applied over the whole transport substrate or only to wear paths.

Abstract: A conveying apparatus (1) for shelf channels of shelf storage facilities comprises two parallely arranged, circulating conveying means (2) for receiving pallets (P). The conveying means (2) are partially designed as support roller chains (3) whose ends are interconnected by a rope (3). Two deflections (5, 6) are provided per conveying means (2) by means of which the particular conveying means is divided into an upper (7) and a lower run (8). In order to bring the two conveying means into a defined initial position after unloading the last pallet, several chain links (3A, 3B, 3C, 3D) of the end region of the particular chain (3) near the unloading end are provided with a smooth surface. Moreover, an end stop member (15, 16) is provided for each conveying means (2) that limits the path of displacement of the chain (3) in the unloading direction.

Abstract: An elongated cylindrical roller tube is rotatably supported between frame members by a pair of bearing units secured to opposite end portions of the tube. Each bearing unit includes a tubular shaft supporting a hexagonal stub axle for axial movement between an outwardly projecting position engaging a frame member and an inwardly retracted position against the bias of a coil spring confined within the shaft. An anti-friction bearing is mounted on the tubular shaft and is retained within the roller tube by an annular adapter. An annular dust cover snap-fits onto the outer end portion of the tubular shaft for protecting the bearing, and the stub axle is retained within the shaft by detents which permit pulling the stub axle from the shaft for axle replacement.

Abstract: An end cap for an idler roller has a first component which is engageable with an idler shell, an inner cover and an outer cover. Two of these end caps are engaged with opposing ends of an idler shell to form an idler roller. The idler roller is assembled by engaging the two end caps with opposing ends of the idler shell, placing the assembly in an injection molding machine and injection molding a plastic coating over at least the shell.

Abstract: A medical table includes a base. The medical table also includes a number of rollers, supported by the base, which collectively define a bed surface for supporting a patient, wherein each roller of the number of rollers (1) defines a fluid impervious bag having a void therein, and (2) contains a plurality of beads within the void of the fluid impervious bag, and further wherein the number of rollers includes a prime roller having a shaft extending therefrom. The medical table further includes a motor mechanically coupled to the shaft of the prime roller. The medical table also includes a vacuum source in fluid communication with each void of the number of rollers. A method of moving a patient from a first position to a second position is also disclosed.

Abstract: The present invention features a universal, low profile, expandable flow track system that can be drop-load mounted to almost any supporting frame or pallet rack. The flow track system of the invention features a flow track that mounts flush with its end supports, and is infinitely adjustable along both the horizontal axis and depth axis of the storage frame. The flow track is quickly assembled to, adjusted upon, and removed from, the storage frame.

Abstract: The invention provides a tubing material suitable for constructing a double-walled dead shaft idler. The idler so constructed is lighter weight than standard idlers. It permits bearings to be mounted at a distance recessed from the ends of the idler, thereby reducing deflection or bending of the idler. The tubing also includes built-in balancing lugs.

Abstract: A roller assembly for a roller conveyor with a replaceable roller sleeve is provided. An axle assembly with a locking piece that frictionally engages the underside of the roller sleeve allows replacement of the roller sleeve, without the need to replace the axle assembly.

Abstract: A conveyor roller includes a generally cylindrical roller tube and a pair of stub shafts rotatably mounted in each end thereof. At least one of the stub shafts is mounted for axial movement between an extended position and a retracted position. When in the extended position, the stub shafts on each end of the conveyor engage respective mounting holes in the conveyor frame. To insert the conveyor roller in the conveyor frame, the movable stub shaft is moved to a retracted position while the roller is lowered into the conveyor frame. When the stub shaft aligns with the mounting holes in the conveyor frame, the stub shaft is urged back to the extended position by a biasing member to engage the mounting hole in the conveyor frame.

Abstract: A roll assembly is disclosed having a roll, a carrier strip secured to the roll, and a replaceable cover strip adhesively bonded to the carrier strip. Upon removal of the cover strip, the adhesive bond causes a portion of the carrier strip to be pulled away with the cover strip. A replacement cover strip can then be adhesively bonded to the newly exposed surface of the carrier strip.

Abstract: A conveying roller includes a shaft and a body member placed on a periphery of the shaft. The body member is provided with an inner layer placed on the periphery of the shaft and an outer layer placed on a periphery of the inner layer. The inner layer is made of a thermoplastic resin having a predetermined volume reduction rate. The outer layer is made of an elastomer. The conveying roller has an increased adhesion between the shaft and the body member.

Abstract: A shaft portion of a retard roller is supported by a pair of supporting members so that the retard roller can be assuredly supported and easily detached. One of the pair of supporting members is provided so as to be movable in the axial direction of the shaft portion. By moving the movable supporting member in a direction of separating from the shaft portion, the retard roller can be detached. A regulation device regulates movement of the movable supporting member in the direction of separating from the shaft portion at a position where the pair of supporting members engage with the shaft portion and is provided on a guide cover for blocking an opening for mounting/detaching the retard roller.

Abstract: An elongated cylindrical roller tube is rotatably supported between frame members by a pair of bearing units secured to opposite end portions of the tube. Each bearing unit includes a tubular shaft supporting a hexagonal stub axle for axial movement between an outwardly projecting position engaging a frame member and an inwardly retracted position against the bias of a coil spring confined within the shaft. An anti-friction bearing is mounted on the tubular shaft and is retained within the roller tube by an annular adapter. An annular dust cover snap-fits onto the outer end portion of the tubular shaft for protecting the bearing, and the stub axle is retained within the shaft by detents which permit pulling the stub axle from the shaft for axle replacement.

Abstract: A roller body having a shaft formed from a first thermoplastic material and defining at least one roller. The shaft is a single component injection-molded shaft. A casing at least partially encases the roller and is formed from a second thermoplastic material different from the first thermoplastic material. The casing is bonded to the roller by an injection-molding process.

Abstract: An improved roller rung for a cable bed to reduce cable traction is disclosed. The roller rung comprises a holder rung having a groove, a plurality of roller drums and a plurality of partition panels. The partition panels are mounted in the groove from above or an end of the groove and securely engaged with the holder rung with panel engagement means. The roller drums turnably engage the partition panels and can rotate freely and independently on axial engagement means substantially above the groove or partially protruding from the groove. Cable weight is securely borne by the partition panels which are supported by the sturdy holder rung, thus the roller rung of the present invention can additionally provide an improved support of cable weight.

Abstract: A cargo roller for use in a roller assembly useful in aircraft or other applications where a high strength to weight ratio is important. The cargo roller includes an outer roller surface and an inner surface which includes at least one stiffening ring formed circumferencially in an inner cavity of the roller. A bearing cavity is formed at each end and preferably the entire assembly is formed from a single piece of aluminum or other appropriate material.

Abstract: The present invention features a new type of spring-loaded axle. The spring-loaded axle of this invention has a single element. The single component of this invention has a specially-designed spring that acts both as a detent and an axle, all in one. The spring includes an elongated, flexible, coiled, spring portion that has a compressible, coiled midsection that is flanked by a generally non-compressible, coiled section on either side of the compressible, coiled midsection. At the distal end of each of the non-compressible, coiled sections is located a flexible, generally non-compressible, curvilinear, coiled end section. Each of the conically-shaped, coiled end sections acts like a detent; further, because of their conical shape, they can automatically adjust to the bores of the supporting frame. The elongated, coiled spring portion acts like an axle.

Abstract: An improved multi-function loading and recovery apparatus for use with pallets, flat racks, containers and the like having a simple, effective design while enabling efficient operation in a wide variety of recovery operations. This multi-function loading and recovery apparatus utilizes a double pivoting tilt frame and self-locking L-arm, and also includes a unique inside-outside rail option, a collapsible bumper, forward-mounted rollers, an improved rear stabilizer and other features.

Abstract: A tree-trunk feed roller of a log harvesting unit includes a mantle for engaging the tree trunk, arranged in one piece around a body. In the space radially provided between these elements, one set of dogging elements is mounted on the mantle, and another set is mounted on the body, such that dogging elements of the respective sets alternate. Resilient elements are engaged between each two dogging elements from the opposite sets, such that the dogging elements and resilient elements are arranged to transmit radial and peripheral forces acting between the body and the mantle.

Abstract: The present invention enables a roller in which a radially outwardly protruding flange-like portion is formed on the outer peripheral portion of a roller body portion made of hard synthetic resin and presenting a substantially disc-like shape.

Abstract: An end cap assembly (10) for a roller tube (76) of a conveyor roller (78) comprising an end cap body (12) proportioned to press fit within an end of the roller tube (76), a bearing retained between the end cap body (12) and a shaft (74) of the conveyor roller (78) and a seal (16) provided about the shaft (74) and abutting an outer surface (18) of the end cap body (12) so as to restrict the passage of dust and other materials into the bearing (14).

Abstract: The invention provides a slab transport tire roller which is easy to assemble and wherein a heat-insulating material is protected to render the roller reliably operable over a prolonged period of time. The tire roller comprises tires fixedly arranged respectively on outer peripheral portions of a pipe for passing cooling water therethrough, and a tubular protective sleeve fitted around the pipe between the tires with the heat-insulating material accommodated in the sleeve. The protective sleeve is engaged with the pipe or with at least one of the tires adjacent to the sleeve rotatably therewith. The protective sleeve can be composed of a tubular sleeve member and side plates attached to respective open ends of the sleeve member.