Abstract: A constant velocity joint for a vehicle. The constant velocity joint includes: an axle housing fixed to a knuckle by a hub bearing, and a joint assembly inserted into the axle housing to transmit power from a shaft to the axle housing through a plurality of joint balls. In particular, the axle housing includes an extension portion which is extended from an end portion of the axle housing in a radial direction of the axle housing, and the extension portion provides a pressing force to an inner race of the hub bearing in an axial direction of the axle housing. The constant velocity joint further includes a boot surrounding an outer side of the extension portion and coupled to the extension portion so as to form a restraining force between the extension portion and the boot in the axial direction.

Abstract: Disclosed is a protective bellows (1) in the form of a tubular body (2) open at each of its ends, the body (2) having two zones (3, 4) of differentiated cross-section, one (3) of the zones (3, 4) of smaller cross-section called the small base (3) of the body (2) and the other zone (4) of larger cross-section called the large base (4) of the body, the zones (3, 4) being separated from each other by a wall referred to as the deformable outer radial wall of the body (2), this wall (6) extending transversely to the longitudinal axis of the body (2). The outer radial wall (6) of the body (2) is provided, at its zone (12) connecting to the large base (4) of the body (2), with an outer peripheral groove (7) with an outer radial opening (8), this groove (7) having one of its sides (9, 10) and the bottom (11) of the groove (7) projecting from the face (61) of the deformable outer radial wall (6) turned towards the small base (3) of the body (2).

Abstract: A helicopter is described comprising a motor member comprising an output shaft and a first stator rotatably supporting the output shaft around a first axis; a main rotor adapted to provide the lift necessary for the support and the thrust necessary for the movement of the helicopter; a transmission interposed between the motor member and the main rotor; the transmission rotatable around a second axis and a second stator rotatably supporting the input shaft around the second axis; the helicopter also comprises a joint interposed between the first and second stator, angularly fixed with respect to the first axis, and configured to allow an inclination between the first and second stator in a plane parallel to said first axis; the joint comprises a first corrugated element made of an elastically deformable material, interposed between said first and second stator, and adapted to allow the inclination through elastic deformation.

Abstract: An apparatus for correcting an imbalance in a rotating shaft and a method for correcting the imbalance in a rotating shaft. The joint assembly includes a first joint member that is drivingly connected to at least a portion of second joint member via one or more torque transmission elements. At least a portion of a first shaft is drivingly connected to at least a portion of a first joint member and at least a portion of a second shaft is drivingly connected to at least a portion of a second end portion of the second joint member. A boot can is connected to at least a portion of a first end portion of the second joint member and one or more balancing elements are attached to at least a portion of the boot can.

Abstract: A driveshaft has an elongated rotary slip sub, a tube sleeve telescopically engaged with the slip sub, a bearing assembly mounted on the slip sub by a roller, a retaining part positioned on the bearing assembly, and a cover extending radially outwardly of the slip sub. The roller is adjacent a movable end of the tube sleeve. A bellows is secured to an adjacent tube sleeve. The retaining part holds the bellows on the bearing assembly. The cover covers the roller.

Abstract: A constant velocity joint boot assembly includes a flexible boot having a flexible portion extending between a first end and a second end along an axis. The first end is disposed about a portion of a constant velocity joint and the second end is disposed about a portion of a shaft assembly. The first end defines a skirt having an engineered portion that elastically absorbs and/or reflects impact energy.

Abstract: A constant velocity joint assembly includes a constant velocity joint. The constant velocity joint assembly also includes a sealing boot in contact with the constant velocity joint. The constant velocity joint assembly further includes a boot protector disposed on a radially outer surface of a portion of the sealing boot. The constant velocity joint assembly yet further includes a first fastener coupled to the boot protector to secure the boot protector to the constant velocity joint.

Abstract: A boot for a shaft assembly joint and method of construction thereof are provided. The boot has a flexible hollow wall extending about a central axis between a first end and a second end. The first end has a skirt portion configured for snug engagement with an outer surface of a housing of the constant velocity joint and the second end has a neck portion configured for snug engagement with an outer surface of a shaft extending away from the constant velocity joint. At least one of the skirt portion and the neck portion has interior surface formed of a first material having a first coefficient of friction and an exterior surface formed of a second material having a second coefficient of friction, the first coefficient of friction being greater than the second coefficient of friction.

Abstract: The invention relates to a sealing apparatus for sealing the ball joint of a kingpin comprising at least one holding ring and at least one seal ring, wherein the seal ring is provided at least partially within a groove of the holding ring, and wherein the groove is provided in a radially inwardly disposed region of the holding ring.

Abstract: A boot can be fastened to a joint housing with a seal. The boot includes a first and a second fastening region, and a pleated region between them. The first fastening region comprises lobe regions and/or guide regions, and connecting regions and a connector seat region, which comprises at least two grooves in at least the lobe regions and/or the guide regions, starting from the connector seat region surface, said grooves being parabolic when viewed in the cross sections and having different depths inside the lobe regions and/or the guide regions.

Abstract: A boot is provided with an improved sealing effect. The boot has a first and a second fastening region, and a pleated region between them, wherein the first fastening region comprises lobe regions and/or guide regions, and connecting regions and a connector seat region that has a connector seat region surface and an undersurface lying opposite it, wherein there is at least one inner groove in the lobe regions and/or in the guide regions, on the undersurface.

Abstract: It is a technical object of the present invention to provide a boot clamping structure for a constant velocity joint that can securely fasten a clamp and a boot so that the clamp and the boot do not run against each other. To this end, the boot clamping structure for a constant velocity joint of the present invention is a boot clamping structure for a constant velocity joint for fastening both ends of a boot using a clamp, and includes a main pressing portion that is provided to be protruded in a first direction toward the boot on an inner circumferential surface of the clamp.

Abstract: A boot includes a large-diameter tubular portion, a small-diameter tubular portion, and a bellows portion. The large-diameter tubular portion includes a fastening groove into which a fastening member is fitted, an opening end to which the bellows portion is coupled and into which an outer case is inserted, at least one seal lip having an annular shape and protruding from an inner circumferential surface of the large-diameter tubular portion at the position where the fastening groove is projected to the inside in the radial direction, so as to be continuous over the entire circumference, and a protrusion protruding from the inner circumferential surface on the opening end side with respect to the seal lip so as to be provided over the entire circumference. A height of the protrusion is set to be smaller than a height of the seal lip.

Abstract: A joint assembly for a vehicle. The joint assembly incudes an outer race having a stepped portion with a chamfer portion circumferentially extending along an outer surface of an axially outermost end of a second end portion of the outer race. A first end portion of a flexible boot is connected to an outer surface of the outer race. Integrally connected to an inner surface of the boot is an adapter. Circumferentially extending from a first side of the adapter is an outer race mating portion having a size and shape complementary to the stepped and chamfer portions of the outer race. Extending radially inboard from the outer race mating portion is a substantially disc-shaped portion. A first side of the disc-shaped portion is in contact with the axially outermost end of the outer race and a second side is in contact with the inner surface of the boot.

Abstract: A constant velocity joint and flexible boot assembly. The constant velocity joint includes an outer race having a first end portion and a second end portion. The first end portion of the outer race is connected to a first shaft. A second end portion of a flexible boot includes an attachment portion having a groove circumferentially extending along at least a portion of an outer surface of the attachment portion. The attachment portion of the flexible boot is connected to an outer surface of a second shaft. A retaining member has a first and second boot retention leg extending radially inward from at least a portion of an inner surface of the retaining member. At least a portion of the first leg is disposed within the groove and at least a portion of the second leg is disposed axially outboard from a second end of the flexible boot.

Abstract: A constant velocity joint includes a joint body, a boot adapter and a rubber boot, a plurality of fasteners for attaching the boot adapter to the joint body, the fasteners being receivable in a plurality of holes in the boot adapter and a plurality of holes in the joint body, a propeller shaft extending from the boot adapter, and a load distributing washer located between the boot adapter and the plurality of fasteners. The load distributing washer includes an annular disk having a first side and a second side, the annular disk having a clearance shape through which a boot portion of the boot adapter may be inserted, a flange extending perpendicularly from an outer edge of the second side of the annular face, and a plurality of fastener holes for receiving the plurality of fasteners for fixedly attaching the boot adapter to the joint body.

Abstract: Peripheral sealing glands for forming a seal between an elongate member and a substantially flat surface are provided. One method includes providing an at least in part frustoconical shaped skirt through which the elongate member is to pass and defining a deformable upper seal configured to deform about and form a first seal to a periphery of the elongate member, providing a flange depending from a lower periphery of the skirt, and providing a substantially rigid ring structured to bear on the outer surface of the flange so as to apply a substantially consistent pressure to the two or more endless lip seals to form a second seal against the flat surface. The skirt includes a retention flange to removably receive the rigid ring and to permit adjustment of the rigid ring relative to the flange.

Abstract: A constant velocity joint boot assembly includes a flexible boot having a flexible portion extending between a first end and a second end along an axis. The first end is disposed about a portion of a constant velocity joint and the second end is disposed about a portion of a shaft assembly. The first end defines a skirt having an engineered portion that elastically absorbs and/or reflects impact energy.

Abstract: A constant velocity universal joint has a large-diameter mounting portion fastened and fixed by a first fastening clamp onto a boot receiving portion of an outer joint member, and a small-diameter mounting portion fastened and fixed by a second fastening clamp onto a boot receiving portion of a shaft. A circumferential clamp groove to which the first fastening clamp is fitted is formed in an outer peripheral surface of the large-diameter mounting portion. A protruding portion is formed at a boot outer side end portion of an inner peripheral surface of the large-diameter mounting portion. A recessed portion to which the protruding portion is fitted is formed in the boot receiving portion being a cylindrical surface of the outer joint member. A projection is formed in the vicinity of a boot inner side of the recessed portion.

Abstract: A sealing gland is configured to form a first seal between a first elongate member and the sealing gland, and a second seal between a second elongate member and the sealing gland. The sealing gland includes a conical upper section having an upper aperture through which the first elongate member is to pass and defining, at the upper aperture, a deformable upper seal configured to deform about and form the first seal to a periphery of the first elongate member, and a tubular lower section extending from a base of the upper section and having an open lower end through which the elongate members are to pass, the lower section including one or more endless lip seals, the open lower end configured to deform about a periphery of the second elongate member, such that the one or more endless lip seals form the second seal at the second elongate member.

Abstract: An integrated gasket that provides both wildlife protection and ingress protection in a light fixture. The integrated gasket comprises a body that extends from a top annular edge to a bottom annular edge and defines a through cavity. The body includes a bottom flanged portion and a top pipe receiving portion. The top pipe receiving portion includes a first pipe portion and a second pipe portion that are detachably coupled. Further, the body includes a wiper flange that extends radially inward from the bottom annular edge towards the internal through cavity.

Abstract: A peripheral sealing gland is configured to form a seal between an elongate member and a substantially flat surface having an aperture into which the elongate member extends. The sealing gland includes an at least partially frustoconical shaped skirt through which the elongate member is to pass and defining an upper seal structured to deform about and form a first seal to a periphery of the elongate member. The sealing gland includes a flange depending from a lower periphery of the skirt and having an endless lip seal, and a ring configured to bear on the flange so as to apply a pressure to the endless lip seal to form a second seal against the flat surface. The sealing gland includes a resealable split extending from the upper seal to a peripheral edge of the flange, and a compression clamp configured to close the resealable split, forming the first seal.

Abstract: The invention relates to methods of providing peripheral sealing glands for forming a seal between an elongate member and a substantially flat surface. One method includes providing an at least in part frustoconical shaped skirt through which the elongate member is to pass and defining a deformable upper seal configured to deform about and form a first seal to a periphery of the elongate member, providing a flange depending from a lower periphery of the skirt, and providing a substantially rigid ring structured to bear on the outer surface of the flange so as to apply a substantially consistent pressure to the two or more endless lip seals to form a second seal against the flat surface. The skirt includes a retention flange to removably receive the rigid ring and to permit adjustment of the rigid ring relative to the flange.

Abstract: A sealing member for sealing over an aperture in a surface. The member comprises a flange formed from a resilient material for sealing against the surface around the aperture in the surface. A strengthening member supports the flange. A retaining portion formed from the resilient material is provided on an outside surface of the strengthening member to secure the strengthening member to the flange. The retaining portion is integrally formed with the flange via a through hole in the strengthening member.

Abstract: A connection part providing communication between biopharmaceutical containers and/or conduits, includes a connection sheath (32) and two connection skirts (38a, 38b). The connection sheath (32) and both connection skirts (38a, 38b) have resiliency such that the connection part (30), from a disassembled state, is transversely stretchable, at the site of both connection skirts (38a, 38b) thereof, until transversely widened without loss of integrity so as to be made threadable through both collars (14, 24). Then, due to the resiliency thereof, the connection part contacts, with resilient clamping for support and with sealability, the coupled portion of the outer surface of both collars (14, 24). Moreover, from the assembled state, the connection part is transversely stretchable, at the site of both connection skirts (38a, 38b) thereof, until transversely widened so as to be capable of being unthreaded from both collars (14, 24) and thus be converted to the disassembled state.

Abstract: A plug-in constant velocity joint has an outer race and an inner race. The inner race has a plurality of splines and inner tracks. A cage is located between the outer race and the inner race. A boot sleeve is disposed against the inner race and has a first end portion, a middle portion, and a second end portion. The first end portion defines a race seat and is in contact with an end of the inner race. The second end portion defines an inner ridge, a sleeve channel and an outer ridge. A boot assembly is coupled to the outer race and comprises a boot retainer and a boot. A plug-in stub shaft is engaged with the boot sleeve and both are drivingly engaged into the inner race.

Abstract: A rolling boot comprises a first fastening region for fastening the boot to a joint casing, a second fastening region for fastening the boot to a shaft, and a fold region between the first and the second fastening region with a first fold near to the first fastening region and a second fold near to the second fastening region. The boot further comprises, between the first fastening region and the first fold, a first transition region comprising a first flange neighbouring the first fastening region with a bottom. A ratio between a first minimal diameter D1, defined by the bottom of the first flange of the first transition region, and a second maximal diameter D2, defined by the first fold, where both are viewed in a longitudinal section direction along the main axis, is between approximately 1:1.01 to approximately 1:1.25.

Abstract: The present disclosure provides for a boot for joints, such as constant velocity joints, having a first attachment region and a fold region with a plurality of folds with peaks and roots and a transition area adjacent to the last fold arranged near said first attachment region, said transition area comprising a connecting root between said last fold in the transition part, wherein at least part of said transition part being inclined towards said first attachment region.

Abstract: A constant velocity joint may include a shaft and a boot assembly. The boot assembly may include a boot having a boot neck. The boot neck may include a boot lip. A shaft may be rotationally coupled to a housing and may define a shaft groove. An attachment mechanism may be integrated within the boot neck. The shaft groove may be configured to receive the boot lip and the attachment mechanism may exert a radial force on the groove to secure the boot neck to the shaft.

Abstract: A boot for joints, such as constant velocity joints, has a first attachment region and a fold region with a plurality of folds with peaks and roots and a transition area adjacent to the last fold arranged near said first attachment region. The transition area comprises a connecting root between said last fold in the transition part, wherein at least part of said transition part is inclined towards said first attachment region.

Abstract: A folding bellows arrangement, e.g., for a tripod joint unit, may comprise a joint outer part with a groove, a folding bellows with a joint collar region for attachment to said joint outer part, and an adapter ring. The joint collar region may comprise a joint binder seat region. The adapter ring may have an inner surface that is matching in a cross section to an outer contour of the joint outer part. On an inner area of the joint collar region and within the joint binder seat region of the folding bellows, at least one bead may be arranged. The bead matching a groove may be arranged on an outer area of the adapter ring. The groove of the adapter ring may correspond to at least one first sealing lip arranged on an inner area of the adapter ring, and at least one second sealing lip may be arranged on the inner area of the adapter ring. The first and second sealing lips may be arranged within the groove of the joint outer part.

Abstract: A boot assembly includes a boot and a retention band. The retention band includes a ring, a lever attached to the ring and a clasp associated with the ring and configured for selective engagement with the lever. The boot includes an annular wall defining a hollow interior configured to receive a portion of a drive assembly of a vehicle. The boot further includes a rib, the rib being integral with the annular wall and extending radially outwardly from the annular wall. The rib and the annular wall cooperate to define an annular channel that is configured to receive the retention band. The rib extends radially outwardly beyond the ring, the lever and the clasp of the retention band when the retention band is seated within the annular channel.

Abstract: A folding bellows arrangement for a tripod joint unit is described. The bellows arrangement comprises a joint outer part with a groove; a folding bellows with a joint collar region for attachment to said joint outer part, and an adapter ring. The joint collar region comprises a joint binder seat region. The adapter ring has an inner surface that is matching in a cross section to an outer contour of the joint outer part. On an inner area of the joint collar region and within the joint binder seat region of the folding bellows, at least one bead is arranged. The bead matching a groove is arranged on an outer area of the adapter ring. The groove of the adapter ring corresponds to an at least one first sealing lip arranged on an inner area of the adapter ring, and wherein on the inner area of the adapter ring at least one second sealing lip is arranged. The first and second sealing lips are arranged within the groove of the joint outer part.

Abstract: The present disclosure provides for a boot for joints, such as constant velocity joints, having a first attachment region and a fold region with a plurality of folds with peaks and roots and a transition area adjacent to the last fold arranged near said first attachment region, said transition area comprising a connecting root between said last fold in the transition part, wherein at least part of said transition part being inclined towards said first attachment region.

Abstract: An expanding bellows is disclosed for sealing an annular gap between two parts, which are connected to one another in a rotationally fixed manner and may be angled to one another, in a constant velocity joint. The expanding bellows has a first larger flange and a second smaller flange and an annular fold area, which extends between the first flange and the second flange, having annular folds implemented as outer folds, each having two annular flanks and a fold peak between two fold valleys. The expanding bellows further comprises a first area of at least two annular folds adjoining the first flange having diameters of the fold peaks and fold valleys decreasing in the direction toward the second flange and a second area having at least one annular fold adjoining the second flange having essentially uniform diameters of the fold valleys. A use of the expanding bellows is also disclosed.

Abstract: A boot which has reduced deformations during operation is disclosed. The boot includes a first fastening region, wherein the first fastening region is displaced axially, with respect to the direction of a main axis of the boot, and with respect to a housing part on which the boot can be mounted, in such a way that the first fastening region at least partially projects beyond an edge of the housing part.

Abstract: The outer peripheral surface of the boot attaching section of an outer joint member (2), when viewed in cross section, is non-cylindrical, with a large diameter section (22a) and a small diameter section (22b) appearing alternately.

Abstract: A constant velocity universal joint has improved sealability of the boot thereof and facilitates the positioning of the end sections of the boot in the axial direction at low cost while ensuring the strength of the outer race thereof. Protruding sections having a pointed shape at the tip ends thereof and having a triangular shape in cross section are provided on the inner peripheral surfaces of the large-diameter end section and the small-diameter end section of a boot. Sealing sections are respectively disposed annularly on the inner peripheral surfaces of the large-diameter end section and the small-diameter end section on the portions equally distant from the protruding sections on both sides thereof in the axial direction.

Abstract: A rolling boot is proposed that has a first fastening region and a fold region with at least a first fold having a first fold peak region and a first fold flank near the first fastening region and, opposite this first fold flank, a second fold flank which is adjoined by a fold trough, wherein a transition region having a base surface is arranged between the first fastening region and fold region, and an angle a having a range from approximately 90° to approximately 140° is formed between the base surface and an outer side of the first fold flank, and the fold trough has a depth T which is, at most, approximately 65 percent of a height H of the first fold.

Abstract: A method for fixing a boot includes mounting a tubular anchoring areas, defined in opposite ends of a resinous boot, on an outer periphery of a counterpart member, and applying a clamping force to boot bands mounted around respective outer peripheries of the tubular anchoring areas to thereby fix the tubular anchoring areas to the outer periphery of the counterpart member. Coils are disposed around respective outer peripheries of the boot bands to generate an induction current in the boot bands. In this way, a reactive force of the magnetic field is generated between the coils and the boot bands to plastically deform the boot bands and reduce their diameters, whereby the tubular anchoring areas are fixed to the outer periphery of the counterpart member.

Abstract: A silicone boot for a constant velocity universal joint includes a larger diameter portion attached to an outer joint member of a constant velocity universal joint, a smaller diameter portion attached to a shaft coupled with an inner joint member of the constant velocity universal joint, and a bellows portion, which is arranged between the larger diameter portion and the smaller diameter portion, and has peak portions and valley portions formed alternately with each other. The smaller diameter portion includes a shaft attachment portion having a radially outer surface in which a fitting groove for attachment of a boot band is formed, and a thin portion extending from the shaft attachment portion so as to be coupled with the bellows portion through intermediation of a thick portion and allowing buckling deformation with respect to the shaft attachment portion and the bellows portion.

Abstract: A boot assembly and constant velocity joint utilizing the boot assembly is provided. The constant velocity joint and boot assembly includes a first shaft, the first shaft having an axle portion extending between a first end and a second end, at least one of the first end and the second end having an enlarged joint portion. It also includes a hollow boot disposed on the first shaft having a joint end and a shaft end, the joint end disposed proximate the enlarged joint portion and the shaft end disposed proximate the axle portion. The constant velocity joint also includes a spacer, the spacer having an inner surface disposed on the axle portion and an outer surface having the shaft end of the boot disposed thereon.

Abstract: A boot assembly includes a boot and a retention band. The retention band includes a ring, a lever attached to the ring and a clasp associated with the ring and configured for selective engagement with the lever. The boot includes an annular wall defining a hollow interior configured to receive a portion of a drive assembly of a vehicle. The boot further includes a rib, the rib being integral with the annular wall and extending radially outwardly from the annular wall. The rib and the annular wall cooperate to define an annular channel that is configured to receive the retention band. The rib extends radially outwardly beyond the ring, the lever and the clasp of the retention band when the retention band is seated within the annular channel.

Abstract: A joint seal of a constant velocity universal joint which has a sealing effect relative to a shaft journal includes an axial securing sleeve which is connected to the inner joint part and which ends in individual axial fingers which radially elastically engage an annular groove in the shaft journal, wherein the ventilation channels for the joint interior of the constant velocity universal joint are formed by axial slots between the individual axial fingers which freely end in the interior of the rolling boot and can be closed towards the outside of the rolling boot by a sealing lip which is formed on to the rolling boot, which, in the position of rest, annularly sealingly contacts the shaft journal and which, at an increased speed, lifts off the shaft journal to expose the ventilation channels.

Abstract: A safety guard for a double universal joint (1) rotatingly arranged around an axis of rotation has a tubular protective cone (15). The cone (15) has a connection mechanism to non-rotationally connect the protective cone (15) to a drive shaft guard of a shaft connected to the double universal joint (1). A sliding ring (16) rotatingly supports the safety guard on the double universal joint (1). It is non-rotationally connected to the protective cone (15). An adaptor ring (22) is non-rotationally connected to the protective cone (15). A boot (23) is non-rotationally connected to the adaptor ring (22). The boot (32) has a connection mechanism to non-rotationally connect the boot (23) to a stationary component.

Abstract: A boot-mounting structure for a constant velocity universal joint has a configuration which can prevent a crack caused by interference with a boot band while maintaining a stable sealing property. The boot band (69) is fitted into a fitting groove of a silicone boot (65), and is decreased in diameter while being attached into the fitting groove, to thereby fix the silicone boot (65). The boot band (69) is formed into an annular body not provided with a folded-back portion. There is provided a no-interference structure means (S) for preventing interference caused, when the boot band is decreased in diameter, between an axial outer-peripheral-edge portion (69a or 69b) of the band (69) and a bottom end portion (82a or 82b) of the fitting groove (75) corresponding thereto.

Abstract: A boot is disclosed having a first attachment region which is assigned to a joint, and a second attachment region which is assigned to a shaft. The boot has a plurality of folds, including a first fold region with at least two folds with a diameter that decreases in the direction of the second attachment region and at least one revolving, separating element which is arranged in an annular fold root between two folds.

Abstract: A constant velocity joint assembly includes an outer joint member and an inner joint member. A first shaft is coupled to the inner joint member for articulated movement with the inner joint member relative to the outer joint member. A boot is coupled to the first shaft and the outer joint member to seal the constant velocity joint assembly. An insert is secured to and supported within the boot adjacent to and in abutting engagement with an axial end of the outer joint member. The insert limits movement of the first shaft to within a pre-determined range of articulation to prevent disengagement and/or disassembly of the inner joint member relative to the outer joint member.

Abstract: A bellows for a joint arrangement may include pleats, an axis and a joint end, a zone of the joint end being produced by blow molding and forming a receiver for a retaining ring. The receiver, in the proximity of the pleats, has a plurality of outward-pointing bulged portions that form a recess and at least one inclined receiving edge.

Abstract: The outer peripheral surface of the boot attaching section of an outer joint member (2), when viewed in cross section, is non-cylindrical, with a large diameter section (22a) and a small diameter section (22b) appearing alternately.