Abstract: An assembly for connecting a component having a base to a surface includes a fastener and a retainer having a clamp portion for capturing a shank of the fastener, and for aligning the fastener and an optional gasket with the base. The retainer automatically separates from the fastener when the fastener is tightened, and may include a recovery feature to allow recovery of the retainer after separation. A method for facilitating connection of a component and gasket to a surface includes inserting a threaded fastener into a base of the component, capturing the fastener within a clamp portion of a retainer, and positioning a surface of the retainer adjacent to the base. A tab portion of a gasket or the base can be inserted into a slot in the retainer to thereby secure the retainer to the base prior to connecting the component to the surface.

Abstract: A captive structural fastener including an integral hold-out feature is provided. The fastener includes a stud assembly including a stud, a retaining ring including two oppositely disposed tabs protruding toward the center of the retaining ring, a first sleeve that is matingly engageable with a second sleeve, the second sleeve including an inwardly disposed channel for receiving the retaining ring; and a receptacle assembly, the receptacle assembly including a bracket constructed and arranged to be secured to a panel, an internally threaded nut, a retaining clamp for securing the nut in the bracket, and a grommet assembly including means defining a bore for receiving the stud therethrough.

Abstract: A fastener assembly including a retention and alignment element used in combination with a first component having a cylindrical wall defining a bore and a second component having an elongated shaft for insertion into the bore of the first component. The retention and alignment element comprises a plurality of elongated polymeric protuberances, each having (i) a base fixed to the cylindrical wall of the first component, (ii) a height sufficient so that together the free ends of the protuberances define a passageway that creates an interference fit with the shaft of the second component, and (iii) a length sufficient to maintain the shaft of the second component generally collinear with the axis of the bore of the first component.

Abstract: A retractable nail includes a head portion having a striking surface and a slot through the striking face. The slot is configured for receiving a removal tool. The nail includes a piercing part the head portion and the piercing part. A longitudinal main body is positioned between the longitudinal main body includes a front side, rear side and two lateral sides. The front and rear sides include respective front and rear helical thread segments formed along a longitudinal length of the main body. The threads are filled or covered with a plastic material, epoxy, glue, composite or the like to prevent damage to the helically threads when the device is hammered or bored with a pneumatically or electrically powered nail gun into a solid material.

Abstract: This device for holding screw-like means (1) in position in a through-hole (2) in a first part (3) for clamping the first part to a second part is characterized in that it comprises a one-piece tongue (4) comprising a central portion provided with a tapped hole (5) for receiving screw-like means (1) and either side of which extend two resilient wings (6, 7) intended to engage with clearance in apertures (8, 9) in the first part to allow the screw-like means to be held in position with clearance in the hole (2) in this first part.

Abstract: A flat nut is provided with a threadlike retainer cord and structure for self-drilling and slotting a wall to provide a suitable hole for insertion of the nut, and a screw to be threaded into the nut. The retainer cord provides for positioning the nut on the back side of the wall. The nut has an elongated drilling point for making a hole and serrated teeth along an elongated side for making horizontal slots on each side of the hole to accommodate the full width of the nut. The arrangement provides a simple way to fasten objects onto a wall without access to both sides.

Abstract: A fastener system for retaining a loose elongate fastener in a counterbore, including an elongate fastener, such as a bolt, having a head for being received and retained in a counterbore in a structure and in generally flush relation to a surface of the structure surrounding the counterbore, and a retaining member for being secured to the structure proximate the counterbore and overlapping the counterbore to trap the loose fastener in the counterbore.

Abstract: A compression limiter includes a tubular-shaped wall having an outer surface and an inner surface forming a central passage. A plurality of perforations extend through the wall from the outer surface to the inner surface. A plastic component can be formed with the compression limiter by over-molding a plastic body over the compression coupler and extending the plastic body into the plurality of perforations. The compression limiter is thereby firmly secured to the plastic body. Different sized fastener openings can be formed within the compression limiter by extending the plastic body into the central passage of the compression limiter and/or substantially preventing the plastic body from extending into the central passage of the compression limiter.

Abstract: The invention relates to a fastening element comprising a clip part (4), which has a top plate (10), a base plate (3) and a joining section (9). A cutout (11) is made in the top plate (10), and a cutout (5) is made in the base plate (3), these cutouts facing one another. The fastening element also comprises an elongated shaft part (1), which is formed on the base plate (3), has a smooth-wall shaft cutout (2) that leads into the cutout (5) in the base plate and which provided for receiving a connection part. This connection part is provided with an external thread having a nominal diameter and can be guided through the cutout (11) in the top plate and through the cutout (5) in the base plate (3). The cutout (11) in the top plate has, at least in sections, a diameter that is less than the nominal diameter of the external thread but greater than the inside diameter of the shaft cutout (2).

Abstract: A method of attaching a housing (such as a security system device housing) to a wall. A housing is provided with at least one mounting portion that has a mounting hole surrounded by a substantially thin lip. The housing is held by the installer in the exact desired position on the wall. The installer the inserts a wall anchor through the mounting portion and into the wall, typically with a screwdriver. The wall anchor has a cylindrical body with a flanged end and an insertion end, with the body having an exterior thread disposed thereon and the insertion end having a generally flat pointed extension of the body. The flanged end of the anchor has a recess suitable for insertion of the screwdriver. The installer inserts the anchor by pushing the extension through the mounting hole of the mounting portion and into the wall with the screwdriver engaged in the recess such that the extension is substantially within the wall.

Abstract: An object such as an electromagnetic valve is resiliently mounted (or in a floating manner) on a mounting base such as an intake manifold of an internal combustion engine. A valve port of the electromagnetic valve is connected to a connecting hole of the intake manifold via an O-ring, and a stay connected to the electromagnetic valve is coupled to a bolt via a resilient member such as a grommet. The bolt is rotated to be fastened to the intake manifold by screwing. A rod portion of the bolt is inserted into a hole of the grommet. Projections and depressions such as grooves extending along the rotational direction of the rod portion are formed on the inner surface of the grommet hole to reduce a contacting area and abrasion force between the grommet and the rod portion. In this manner, deformation of the grommet caused by rotation of the rod portion is suppressed.

Abstract: A socket connector for electrically connecting an IC package and a printed circuit board, includes a housing receiving a number of contacts, a stiffener surrounding the housing, a cover pivotably mounted at an end of the stiffener to cover the housing and a lever pivotably mounted at an opposed end of the stiffener to retain the cover to the stiffener, a number of washers mounting to the stiffener and a number of screws for mounting the stiffener to the printed circuit board. The washer has a pinhole and a number of teeth upwardly extending along a circle circumference of the pinhole. The screw is hold to the washer by the teeth of the washer before the screw engaged with the printed circuit board.

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: This system for electrically connecting and fastening at least one plate-type electrical conductor onto a support piece provided with a threaded pin designed to be engaged in a corresponding hole of conductor and to cooperate with a nut for screwing conductor onto support piece, is characterized in that an annular spacer of electrically conductive material is joined to conductor on the side of this conductor that is facing the support piece and in that nut is positioned on the other side of conductor, and is joined to spacer by coupling means allowing the rotation of the nut relative to the spacer and a determined course of axial movement for nut relative to this spacer, between a position of assembling distant from the conductor and a position for screwing in which the nut is supported against the conductor, in order to facilitate the positioning and then the screwing of the conductor against the support piece.

Abstract: A captive shoulder nut for a electronic module heat sink has a threaded nut portion and a tubular portion extending therefrom. A ramped section in the exterior wall of the tubular portion leads to a retaining groove adjacent the bottom face of the nut portion. A compression spring is slipped over the tubular portion to ride over the ramped section and be retained at one end in the retaining groove. The tubular portion is suitable to be inserted through a straight hole, whereof the inner diameter of the spring is larger than the hole. The free end of the tubular portion is suitable to be flared to a larger diameter than the hole, thereby establishing a captivation.

Abstract: A door handle device for vehicles is capable of preventing falling of the screw locking member and the screw and improving the assembling workability. In the door handle device (1) for vehicles including a handle base (3) to be fixed to a door panel (5) by screwing, the handle base (3) has a through hole (18) for inserting a screw (6) thereinto, and a screw locking member (14) into which a fore end of the screw (6) inserted into the through hole (18) is to be screwed, the screw locking member (14) being formed integrally with the handle base (3) so that the screw locking member (14) can be moved to a position corresponding to the through hole (18).

Abstract: A shippable in-assembly bolt having a head portion, a threaded portion containing threads and a gripper portion, wherein the gripper portion preferably comprises a grooved structure and an o-ring. The o-ring is intended to sit between the inner wall of a clearance hole in an assembly/subassembly and the grooved structure of the gripper portion. When the o-ring is in position between the inner wall of the clearance hole and the grooved structure of the gripper portion, the o-ring is in both compression and tension and acts to retain the bolt in the assembly during shipping operations. The invention can be used with any type of mechanical fastener, such as bolts, screws, pins, rivets, etc.

Abstract: A telescopic captive fastener has a knob, a ferrule, a spring, and at least one sleeve. The sleeve extends telescopically between the ferrule and the knob.

Abstract: A fastener assembly includes a grommet having an enlarged bulbous body and a cylindrical extension projecting therefrom, the projection and body defining axially aligned openings therethrough. The cylindrical projection is configured to retain a washer on the outside thereof and a fastener on the inside thereof.

Abstract: A captive screw for use in electronic assemblies includes a screw with a shaft having a pair of spaced grooves and a cover captivating the screw and for attaching the captive screw. A knob for rotating the screw can be moved along the shaft between an extended position and a lowered position corresponding to the grooves on the shaft, and releasably locked to the shaft in either position. A lock wafer is used to secure the knob to the shaft. A release button with a large head actuates the lock wafer.

Abstract: A housing assembly for a printed circuit board is mounted on a vehicle body by pressing a collar nut or the head of a collar screw past a plurality of fingers of a housing assembly so that the fingers retain the nut or screw head in place. The module is then pressed against the vehicle body so that the collar nut or collar screw is lifted while the retainers are deflected outwardly and a tool is used to tighten the screw into a nut or the nut onto the shank of a screw to clamp the printed circuit board on the housing against the vehicle body.

Abstract: A supporting sleeve configured for introduction into a penetration in a component. The hole of the supporting sleeve is penetrated by a fixing pin that is insertable into a carrier so as to fix the component on a carrier. The supporting sleeve includes a closed ring-shaped cross section and a plurality of axially and inwardly extending recesses extending over the entire length of the supporting sleeve and each of the recesses is formed by inwardly bent walls and a base connecting those walls, the walls being generally radially oriented and configured such that when radial pressure is applied to the supporting sleeve upon introduction into the penetration, each recess moves closer to each other.

Abstract: An attachment device for attaching a substrate to a support structure includes a housing having a space defined by facing wall portions. The space captures a rotatable push nut with flexible teeth. The housing is attached to the substrate using a flange positioned opposite one of the wall portions, the substrate being crimped between the flange and the wall portion. The device may be pushed onto a threaded stud to rapidly affix the substrate to the support structure. The push nut may be rotated within the housing to disengage it from the stud and thereby remove the substrate from the support structure.

Abstract: A draft inducer blower for high efficiency furnaces, including a blower housing having a housing body and housing cover. The housing body includes a plurality of mounting lugs spaced around its outer periphery, through which fasteners are inserted to secure the blower housing to corresponding mounting holes in a furnace wall. The mounting lugs each include a slot-like opening having a web of material therein and, in each mounting lug, a fastener is threaded through an opening in the web to temporarily retain the fastener in position within its associated mounting lug. In this manner, a blower housing may be shipped to a furnace manufacturer or other point of installation with the fasteners temporarily retained within their associated mounting lugs.

Abstract: A flute holder comprises a bracket-engaging portion configured to engage a bracket, and a tool-engaging sleeve connected to the bracket-engaging portion and configured to engage a tool. A holding passage is at least partially defined within the tool-engaging sleeve.

Abstract: A telescopic captive fastener has a knob, a ferrule, a spring, and at least one sleeve. The sleeve extends telescopically between the ferrule and the knob.

Abstract: Vibration-damping ring insert arrangement includes a vibration-damping ring. A hollow cylinder member includes a first end, a second end, and an inner surface that is connected to an outer surface of the vibration-dampening ring. One of an outwardly extending edge and outwardly extending edge segments is arranged at the second end. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

Abstract: A fastener, for use with a sheet-shaped member, comprises a tubular shank, a plurality of holding pieces extending outward from a first end of the shank, a flange extending outward from a second end of the shank, and a plurality of stud-engagement pawls extending into the interior of the shank. The shank has a length less than that of a stem of a stud fixed to a mounting member with which the fastener is to be engaged. When the stud is fully inserted into the tubular shank, the sheet-shaped member is fastened to the stud and the stud stem protrudes from a surface of the sheet-shaped member. The protruding portion of the stem allows an auxiliary member to be mounted thereto.

Abstract: A pop-up fastener including a tubular retainer for one-way passage into a socket. A fastening member slidably extends through the retainer. The fastening member has helical threads at its top and a protrusion at its bottom. A compressed spring is positioned atop the retainer for urging the protrusion into engagement with the bottom of the retainer and for urging the helical threads from the top of the retainer.

Abstract: A bracket and nut assembly including a bracket having a first end and second end. The first end includes a first substantially planar portion spaced apart from and positioned substantially parallel to a second substantially planar portion. A third portion interconnects the first and second portions. A first aperture extends through the first portion and a second aperture extends through the second portion. The first and second apertures are axially aligned with one another. A nut includes a substantially cylindrical hollow body having flats, a first end and a second end. A flange radially extends from the first end. The flange is captured between the first portion and the second portion of the bracket such that the nut is operable to translate and rotate relative to the bracket.

Abstract: A method and apparatus for holding a screw captive to a printed circuit board (PCB), with a channel formed through the apparatus and a mounting hole formed through the PCB being in alignment to allow a screw to pass therethrough.

Abstract: An assembly includes a piece to be held in a bore and a device in which the piece is inserted for holding the piece in the bore. The device comprises a cylindrical sleeve having a series of fins extending longitudinally of an inner surface of the sleeve and projecting inwardly from the inner surface. The fins are skewed in a same circumferential direction relative to radial planes of the sleeve. The sleeve and the fins are integrally formed of resilient flexible plastic. The flexibility of the fins is such that the fins can be readily deflected when engaged by an inserted piece. The device can be used as part of a combination that includes a body having a bore therein, and can be used in a method of holding a piece in a bore of a body.

Abstract: A device for holding a piece in a bore comprises a cylindrical sleeve constructed to be inserted into the bore and held therein by engagement of its outer surface with an inner surface of the bore, and a series of fins extending longitudinally of an inner surface of the sleeve and projecting inwardly from the inner surface of the sleeve, the fins being spaced from each other circumferentially of the sleeve with tips disposed to engage an outer surface of a piece inserted into the sleeve. The sleeve and the fins are integrally formed of resilient flexible plastic, and the fins are skewed in a same circumferential direction relative to radial planes of the sleeve. The flexibility of the fins is such that the fins can be readily deflected when engaged by an inserted piece.

Abstract: A device for holding a piece in a bore comprises a cylindrical sleeve constructed to be inserted into the bore and held therein by engagement of its outer surface with an inner surface of the bore, and an annular bead extending circumferentially and inwardly from the inner surface of the sleeve, the bead being disposed to engage an outer surface of a piece inserted into the sleeve. The sleeve and the bead are integrally formed of resilient flexible plastic.

Abstract: A simplified captive panel fastener including a head, shank, a threaded outer end, and a centrally threaded opening at the outer end. Longitudinal slots extend along the outer end of the fastener to receive a retention washer with inwardly extending prongs. The method of mounting the fastener to its desired location and locking a retention washer and fastener in place is easily performed by employing a tool which disposes the threaded mating part, for example, a screw or bolt, into the central threaded opening of the outer end of the fastener. The head of the screw or bolt has radial extent sufficient to block the slots and prevent loss of the retention washer. Only a common screwdriver is used to mount the retention screw or bolt in the end of the fastener.

Abstract: An assembly of an internally threaded fastener and a stemmed washer is provided, such as for applications in which a standoff is desired between a washer and a mating externally threaded fastener. The stemmed washer includes a washer portion, a retaining portion and a standoff portion. The washer portion is angled relative to the standoff portion. The angle of the washer portion to the standoff portion may be varied to change the effective length of the standoff portion. The retaining portion interfaces with the internally threaded fastener to retain the fastener in the assembly. The stemmed washer may include a skirt that is plastically deformed to capture the fastener. The fastener may include a skirt which similarly plastically to mate with a retaining lip on the stemmed washer. The fastener and washer may be secured in the assembly to permit relative rotation of the fastener with respect to the washer.

Abstract: The invention comprises a tolerance compensating mounting device comprising a bushing having an internal and external thread. The bushing is threaded into a part to be mounted to a surface. A bolt is then threaded into a bushing bore using the internal threads. The internal threads cause an interference fit between the bolt shank and the threads, temporarily preventing further insertion of the bolt. The bolt is then turned further, thereby turning the bushing and causing the bushing to unscrew from the part toward the mounting surface until the bushing seats on the mounting surface, thereby completely compensating for a tolerance gap. As the bolt is turned further, at a relatively low torque the sacrificial internal threads are stripped allowing the bolt to be fully torqued into the mounting surface hole, thereby simultaneously connecting the components with a properly torqued connection while compensating for a tolerance gap.

Abstract: A fastener (1) includes a screw (2) and a supporting element (3). The screw (2) includes a head (4), a shank (8) and a threaded portion (12). The threaded portion (12) is located on the shank (8). The threaded portion (12) includes a thread having an outer diameter (14). The threaded portion (12) includes a thread runout (25) facing the head (4) of the screw (2). The shank (8) includes a shank portion (10) having a diameter (11) which is smaller than the outer diameter (14) of the thread. The supporting element (3) is captively connected to the screw (2), and it includes at least one narrow location (27). The narrow location (27) has a diameter (28) which is smaller than the outer diameter (14) of the thread. The narrow location (27) includes at least one surface element (30, 35) facing the thread runout (25) and forming an enveloping cone (31) enveloping the thread runout (25) to prevent the supporting element (3) from getting clamped at the thread runout (25) of the screw (2).

Abstract: A two-piece fastening system utilizes separate parts, a nut and a retainer, which are securely united from opposite sides of the captivating element such as a sheet or panel. The nut body which has an axial threaded bore includes an integral collar located on one side of the nut having an outside diameter less than the outside diameter of the nut body. A tubular shank unitary with the nut body extends coaxially from the collar, the outside diameter of the shank being less than the outside diameter of the collar. The shank includes an expandable portion near its end which is deformable to provide attachment to the second part, a retainer, which has a bore that receives the expandable portion of the shank. The retainer bore includes an inside wall against which the expandable portion of the shank is forced to achieve attachment of the parts. The width of the retainer is preferably greater than the length of the shank so that once attached, the end of the shank is below the endface of the retainer.

Abstract: A fastening assembly is provided. The fastening assembly includes provision for a stud to be positioned in a plurality of predetermined extended positions, minimizing the amount of clearance required for removing a cover from a substructure.

Abstract: A two-piece panel fastener includes a barrel-shaped metal retainer which holds a screw. The screw includes a threaded shaft and a plastic cap which has longitudinally-extending resilient fingers which engage the outer surface of the retainer to captivate the screw. The retainer has a chamfered top flange along its top edge, a circumferential bulge area around its outer surface approximately in the middle of its length, and a base at the bottom. Two circumferential valley regions of reduced diameter are located along the outer surface of the retainer. The first valley region is located between the chamfered top flange and the bulge area and the second is located between the bulge area and the base. When the fingers occupy either of the valley regions, the screw is captively held at either of two stable positions of retraction or extension. The retainer is preferably rigidly affixed to a circuit board by soldering a base flange at the bottom of the retainer to the top surface of the board.

Abstract: A floating and captured cage nut assembly includes a structural member that is U-shaped with a pair of rolled sides defining mounting legs and a rolled front end defining an anti-rotation flange. The rolled sides of the structural member are positioned on the component and are welded or otherwise secured thereto over the opening during manufacture. The floating and captured cage nut assembly further includes an anti-rotation plate having a hexagonal opening to receive a flange nut and a locking window. The anti-rotation plate and the flange nut are inserted within the structural member and the anti-rotation flange is received within the locking window with clearance to loosely secure the components together. The flange nut is retained on the component, and the anti-rotation plate prevents its rotation. The clearance between the anti-rotation flange and the locking window facilitates the threading of the fastener into the nut within a predetermined tolerance zone.

Abstract: A captive fastener retention member includes a cylindrical body having a flange at one end thereof. Work piece retention members project outwardly of the body for securing the retention member in a bore of a work piece. A dimple projects inwardly in the retention member to hold a fastener. The flange on the retention member rests against a work piece, and is shaped to inhibit scratching or gouging of the work piece surface.

Abstract: The present technique provides a stemmed washer and fastener assembly, which has a fastener retained in assembly with a stemmed washer. The assembly is particularly useful for applications in which a standoff is desired between a washer and a mating fastener. The stemmed washer includes a washer portion, a retaining portion, and a standoff portion. The retaining portion interfaces with the fastener, such as with a plastically deformed skirt portion, to retain the fastener in the assembly. The standoff portion has a toolfree mounting structure, such as a snap-fit member, to mount the stemmed washer and fastener assembly to one or more panels, thereby forming a fastener-panel assembly.

Abstract: A captive screw including a screw and a ferrule is disclosed. One end of the ferrule is adapted for engagement to a hole in a panel to be secured by the captive screw. The screw has an annular flange that is captured within the bore of the ferrule. The screw has a shaft with a threaded portion. The threaded portion of the screw shaft can be made to extend from the ferrule to varying amounts as the screw is moved relative to the ferrule between extended and retracted positions. An optional spring may be provided in the ferrule to bias the screw toward the retracted position.

Abstract: An air bag sensor module fastening device for a vehicle is provided includes a vehicle mounting structure having an internally threaded member. A sensor is secured to a base for sensing vibrations caused by a crash of the vehicle. The base has an aperture extending therethrough that is aligned with the internally threaded member. The aperture includes a retaining portion. A fastener for securing the base to the vehicle mounting structure has a shaft with a head and a threaded portion opposite the head. The threaded portion is temporarily retained within the retaining portion in a shipping position. The threaded portion has a minor diameter and the shaft portion has a shaft diameter less than the minor diameter. As a result, the shaft will not be in an interference fit relationship with the retaining portion so that the compressive load of the fastener alone secures the base to the vehicle mounting structure.

Abstract: A metal gasket is designed so that mounting and removal from a cylinder block using a bolt is easy regardless of the direction of the attaching surface and there is no risk of moving or drop off. The gasket is made of two laminated metal base plates. At a base plate part near a bolt hole of one metal base plate, a bolt engaging piece projects so that the diameter of the bolt hole is smaller than the diameter of the bolt for fastening, and an assistant piece for handling is integrated thereto. At the base plate part of the other plate overlapping the assistant piece, a cut recess is formed. When inserting the bolt into the bolt hole of the metal gasket, the bolt engaging piece is struck against the bolt and is elastically bent, and allows the bolt to pass. The gasket mounted on the bolt is kept at the mounting position by the pressing action to the bolt from the impact resilience force of the bolt engaging piece.

Abstract: A front mounted retaining mechanism including a retention device and a captivatable device. The retention device has a head and a hollow shank. The head or the shank may include inwardly directed threads. The shank may include outwardly directed threads to facilitate mounting within a structure. The captivatable device includes a head and a shank, with the shank including a portion having a greater diameter than the remainder of the shank. That portion may be threads or a retainer ring. The captivatable device is threaded into the retention device in such a way as to allow its captivation therein. Then the first structure is aligned with a second structure into which the captivatable device is mounted.

Abstract: An assembly unit includes a component including at least one through hole and at least one screw. The screw is associated with the through hole of the component. The screw is designed and arranged to produce a thread. The screw includes a head and a supporting surface to face the component. The screw includes a shank at least partly including a thread. The screw in the region of the shank and close to the supporting surface includes an annular channel, the diameter of the annular channel being less than the core diameter of the thread of the screw and the effective axial length of the annular channel being more than the axial length of the through hole. The diameter of the through hole of the component is more than the core diameter of the thread of the screw and being less than the outer diameter of the thread of the screw.

Abstract: This invention relates to a fixing element (1) for fixing insulating strips (5) and optionally, additional sealing strips (6) on a solid substructure (7). A screw (4) and a large-surface washer (2) with a tubular extension (3) are used. A rib (15) that projects radially inward into the displacement area is provided in a partial section of the tubular extension (3), which accommodates a screw bead (11) in such a way that it is axially displaceable. After passing the rib (15) in the direction of the free end of the tubular extension (3), the screw head (11) can rest on the rib in the direction opposite to the screwing-in direction.