GB2256689A

GB2256689A - Locking of nuts to screw-threaded shanks

Info

Publication number: GB2256689A
Application number: GB9208111A
Authority: GB
Inventors: Marco Benito Pagliuca
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-12
Filing date: 1992-04-13
Publication date: 1992-12-16
Also published as: GB9208111D0

Abstract

A nut 19 is locked to a screw-threaded shank 10 by means of a cover 23 which has a splined bore 28 engageable with splines 13 on the shank 10 and which closely engages the outer surface of the nut 19. The cover 23 is retained on the shank 10 by flanges 14 at the end of the shaft 10, the flanges being resiliently deformed inwards by flared portion 27 of the cover 23 as the cover 23 is pushed onto the nut 19. The splines 13 may be axially tapered. <IMAGE>

Description

A LOCKING DEVICE FOR A.SQPEW-THREADED FASTENER The invention relates to a locking device for a screw-threaded fastener and is particularly, but not exclusively, concerned with a locking device for inhibiting the unscrewing of a vehicle wheel nut from a wheel stud.

A problem with vehicle wheel nuts, and particularly in the commercial vehicle field, is the risk of nuts becoming unscrewed from the wheel studs, e.g., due to vibration. Where several wheel nuts have been lost from a wheel, additional stress is placed upon the remaining wheel studs and a dangerous condition can arise An object of the present invention is to provide a device which will enable the foregoing problem to be substantially reduced.

According to the invention there is provided a locking device for a screw threaded fastener comprising a shank having an externally screw threaded section for threaded engagement with a nut and a keying section, and a locking member locatable on the shank so as to engage the nut and keying section and inhibit relative rotation between the nut and the shank.

Interengagement between the locking member and keying section inhibits relative rotation between the locking member and the shank so that with the locking member in position and in engagement with the nut, relative rotation between the nut and shank is inhibited.

Preferably, the locking member is in the form of a cover which receives the nut and preferably has a hollow section of polygonal shape to enable it to fit closely around the nut.

The keying section is preferably in the form of one or more splines which may be co-operable with one or more respective splines formed on the locking member e.g., in an axially extending bore therein.

The shank may have a retention section thereon for retaining the locking member axially in position on the shank. The retention section may be deformable to enable the locking cover to pass thereover and may be arranged to resume its undeformed condition to retain the cover on the shank. Preferably, the locking member is formed with a surface which deforms the retention section as the locking cover pass along the shank towards the nut.

The retention section may be formed with axial slit means to permit the deformation and the locking member may have a recess at one end thereof in which at least part of the retention section locates to retain the locking member axially on the shank To enable the locking member to be removed, the retention section may be deformable by means of a tool which may comprise prong means locatable in recesses formed in the retention means and which are movable towards each other to deform the detention means.

A locking device for a screw threaded fastener in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig.1 is an elevation of a wheel stud for use in the present Fig.2 is an end view of the wheel stud shown in Fig.1 looking in the direction of arrow II in Fig.17 Fig.3 is a view similar to Fig.1 showing an alternative form of keying section on the wheel stud, Fig.4 is a perspective view of a wheel stud of the kind shown in Fig.3, Fig.5 is a cross section through a locking cover of the locking device of the invention shown in position on the wheel stud of Fig.1 and Fig.6 is a cross section through the locking cover shown in Fig,5 on the line VI-VI in Fig.5 when removed from the wheel stud.

A wheel stud 10 has a screw threaded shank 12, a splined section 13 (constituting the aforesaid keying section) and a retention section 11 including flanges 14.

The screw threaded section 12 is of conventional diameter to receive a normal wheel nut 19, the splined section 13 is formed on a shank portion 15 and is of smaller diameter than the root diameter of the screw threaded section 12. The retention section 11 is formed with an axial slit 16 which extends into the shank portion 15 to enable the flanges 14 to be squeezed inwardly so as to close the slit 16. If desired, opposite sides of the flanges 14 may be formed with flats 17 as indicated in broken lines The flanges 14 are formed with diametrically spaced apart recesses 18. The distance D across the flanges is greater than the diameter of the splined section 1 3 w As shown in Fig.1, the splines 13 may be straight axial splines or, as shown in Figs.3 and 4 may be axially tapered.

In Fig.5, a polygonal wheel nut 19 is screwed onto the stud 10 (which extends from, e.g., a brake drum 20) so as to hold a vehicle wheel 22 in place. Once the wheel nut 19 has been tightened, a locking cover 23 is placed in position. The locking cover 23 comprises a cylindrical body 24 having a hollow section 25 which is of polygonal cross section to enable it to be a snug fit over the nut 25 which is received therein. The hollow section 25 terminates at a shoulder 26 having a frusto conical portion 27 leading to an axially splined bore 28. The splines (constituting the aforesaid keying means) in bore 28 are complementary to the splines 13 or 13a.Fig.6 is drawn such that the splines shown in the upper half of the drawing are of a type which would mate with splines 13 and are indicated 13' and the splines shown in the lower half of the drawing are of a type which would mate with splines 13a and are indicated as 13a'.

To assemble the locking cover 23 on the nut 19, the hollow section 25 is passed over the flanges 14 until the frusto conical section 27 abuts the right-hand end of the flanges. The curved periphery of each flange 14 is preferably formed with a chamfer 30 and an axial load is applied to the cover 23 so that the frusto conical surface 27 deforms the retention section 11 by causing the flanges 14 to move inwardly towards each other. The inward movement reduces the width of slot 16 until the flanges 14 can move through the bore 28. It may be possible to manoeuvre the locking cover 23 at an oblique angle along the shank 10 to enable the flange 14 to pass through the bore 28 without the provision of the flats 17.

However, the provision of such flats 17 on the flanges 14 will greatly assist the passage of the flange 14 through the bore 28. The distance across the flats 17 will be slightly less than the inner diameter of bore 28. Once the cover 24 has reached the Fig.S position, the flanges 14 will snap outwardly and locate in the recess 29 to retain the cover in position.

Instead of providing flats 17, a further slit 16a (Fig.4) can be formed in the retention section 11 at right angles to the slit 16 thereby providing four quadrant flanges which can move inwards.

It will be necessary to ensure that the nut 19 is correctly positioned rotationally relative to the spllnes 13, 1Za, so that the cover 23 can locate on the splines 13 and nut 19 correctly. The use of the tapered splines 13a may assist in aligning the cover 24 with the splines during assembly.

In order to release the cover 23 from the nut 19, a tool 32 having prongs 33 is used to deform the retention section 11. The prongs 33 locate in the recesses 18 and are then suitably urged inwardly to deform the retention section 11 of the shank 10 by urging the flanges 14 inwardly to reduce the slit 16.

The cover 23 can then be withdrawn over the flanges 14 and once the flanges enter the bore 28, the tool 32 can be removed and the cover 23 removed completely from the shank 10.

Once the cover 23 has been placed in position as shown in Fig.51 the engagement between the periphery of the nut 19 and the surfaces of hollow interior 25 of the cover and the mating engagement between the splines 13, 13' or 13a, 13a' will prevent rotation of the nut 19 relative to the shank 10. In that way, the device forms a very useful locking device for vehicle wheel nuts. However, it is noted that the invention may have other applications where it is desired to prevent relative rotation occurring between a shank and a screw threaded element included within the term "nut" with which the shank is threadedly engaged.

Claims

CLAIM

1. A locking device for a screw threaded fastener comprising a shank having an externally screw threaded section for threaded engagement with a nut and a keying section, and a locking member locatable on the shank so as to engage the nut and keying section and inhibit relative rotation between the nut and the shank.

2. A locking device according to Claim 1 in which the locking member includes a keying means which engages the keying section.

3. A locking device according to Claim 2 in which the keying section and keying means are of complementary form.

4. A locking device according to Claim 1, 2 or 3 in which the keying section comprises a plurality of splinEP,

5. A locking device according to Claim 2 or 3 or Claim 4 when appendant to Claim 2 or 3 in which the keying means comprises a plurality of splines.

6. A locking device according to any preceding Claim in which the locking means comprises a cover which receives the nut.

7. A locking device according to Claim 6 In which the cover includes a hollow section of polygonal shape to enable it to receive a nut having a polygonal periphery.

8. A locking device according to any preceding Claim in which the shank has a retention section thereon for retaining the locking member axially in position on the shank.

9. A locking device according to Claim 8 in which the retention section is spaced from the screws threaded section.

10. A locking device according to Claim 9 in which the keying section is positioned intermediate the screw threaded section and retention section.

11. A locking device according to any of Claims 8 to 10 in which the locking cover is a snap fit over the retention section.

12. A locking device according to any of Claims 8 to 11 in which the retention section is resiliently deformable to enable the locking cover to pass thereover and is then arranged to resume substantially an undeformed condition to retain the cover on the shank.

13. A locking device according to Claim 12 in which the locking cover is formed with a surface which deforms the retention section as the locking cover passes along the shank towards the nut.

14. A locking device according to Claim 13 in which the surface is of frusto conical shape.

15. A locking device according to any of Claims 8 to 14 in which the retention section includes a radial flange.

16. A locking device according to any of Claims 8 to 15 in which the retention section is formed with axial slit means to permit deformation of the retention means.

17. A locking device according to any of Claims 8 to 16 in which the locking member has a recess therein which locates the retention means.

18. A locking device according to any preceding Claim in which the locking member includes an axial bore formed with keying means which engages the keying section.

19. A locking device according to any preceding Claim in which the keying means extends radially for a distance which is less than the radius of the screw threaded section of the shank.

20. A locking device according to any preceding Claim and where the retention means is provided in which the retention means extends radially for a distance greater than the radial extent of the keying means.

21. A locking device constructed and arranged substantially as described herein with reference to the accompanying drawings.