GB2381842A

GB2381842A - Cover for fastener

Info

Publication number: GB2381842A
Application number: GB0126934A
Authority: GB
Inventors: Robert O'hanrahan
Original assignee: Bradley Doublelock Ltd
Current assignee: Bradley Doublelock Ltd
Priority date: 2001-11-09
Filing date: 2001-11-09
Publication date: 2003-05-14
Anticipated expiration: 2021-11-09
Also published as: GB0126934D0; GB2381842B

Abstract

A cover (18) has a shroud (22) and a nut (26). The shroud (22) engages a fastener (28) and application of a given force to the nut (28) causes the nut (28) to shear from the shroud (22) so that a tool cannot then engage the fastener.

Description

Protective Covers for Fasteners The present invention relates to protective covers for fasteners, a method of protecting a fastener and a fastener when protected by such a cover or by such a method.

Figure 1 is a schematic view of a bolt 10 including a threaded end 12 and a castellated nut 14 with a shank 15 extending between them. In use, the nut is tightened to screw the threaded end 12 into a socket. When sufficient torque is achieved, the nut 14 shears off the bolt at a break located at a narrow waist 16 adjacent to the nut 14.

In this way the bolt cannot be removed subsequently as there is no grip for a spanner on the nut.

The bolt 10 is expensive and time consuming to make as the waist 16 must be accurately machined such that it shears at precisely the correct torque. Furthermore, as the bolt 10 is made from a single piece of metal, considerably expense is incurred in using the same metal for the shank 15, thread 12 and nut 14 as for the waist 16 thus resulting in wastage of expensive material in providing the waist. In addition, as the bolt is made out of hard material, it takes time and is costly on tools to machine out the waist.

It is an object of the present invention to attempt to overcome at least some of the above or other problems.

According to one aspect of the present invention a protective cover includes a first part arranged, in use, to extend at least partially over a fastener, the first

part being connected to a second part that is arranged, in use, to cause the first part to be secured in a position at least partially over a fastener, the cover being configured such that the second part is arranged to break off the first part upon application of sufficient force to the second part.

The first part may be arranged, in use, to be substantially completely coextensive with the fastener.

The first part may be arranged to be spaced from an outwardly facing surface of a fastener. The first part may be arranged to substantially completely surround a fastener.

The cover may be arranged to abut with the fastener to restrict relative movement of the cover with respect to the fastener. The first part may be arranged to abut with a member to which the fastener is secured with such abutment restricting relative movement of the cover and the member to which the fastener is secured. Either or both of these abutments may be arranged, in use, to provide a reactive force whereby the second part, in use, is arranged to break off the first part.

The cover may include a portion of reduced dimensions arranged to form the break between the first and second portions. The portion of reduced dimensions may comprise a narrow cross-section. The portion of reduced dimensions may be defined by an external surface of the cover that tapers inwardly towards the region that is arranged to break from at least one, and preferably two opposed directions. The taper or tapers may be arranged to extend completely around the cover.

The cover may include a threaded portion arranged, in use, to engage a threaded member on which a fastener is located. Rotation of the cover on the threaded portion may be arranged to advance the first part to extend over, or further over a fastener. The break in the cover may be arranged to occur at the end region of the threaded member.

The second portion may be arranged to be engaged by a tool and the second portion may comprise a nut.

The first and second parts may be integrally formed.

According to a further aspect of the present invention a method of protecting a fastener comprises using a protective cover and causing a first part of the cover to be connected to the fastener by exerting a force on a second part of the cover with the second part of the cover being broken off upon application of sufficient force to the second part.

The method may comprise indirectly connecting the cover to the fastener for instance by connecting the cover to a member on which the fastener is also connected. The method comprise applying a force to the second part to cause the first part to extend over or further over the fastener.

The method may comprise causing a force exerted to the second part to be opposed with a reactive force being exerted by abutment of the cover with the fastener. Alternatively or additionally, the method may comprise a

force being exerted on the second part with a reactive force being provided by abutment of the cover with a member to which the fastener is connected.

The method may comprise screwing the cover on to a member to which the fastener is connected to cause axial movement of the cover over the fastener.

The method may comprise locating the protective cover over a fastener that is secured to a vehicle, for instance over a fastener that secures a ball coupling to a vehicle or over a fastener that secures a head coupling onto the overrun coupling of a vehicle.

The present invention also includes a fastener when protected by a cover as herein referred to or when protected by a method of protecting the fastener as herein referred to.

The present invention includes any combination of the herein referred to features or limitations.

The present invention can be carried into practise in various ways but two embodiments will now be described, by way of example, and with reference to the accompanying drawings, in which: Figure 2 is a side view of a first embodiment of a protective cover; Figure 3 is a side view of Figure 2;

Figure 4 is a side view of a second embodiment of a protective cover 20, and Figure 5 is a side view of Figure 4.

As shown in Figures 2 and 3, the cover 18 includes a shroud 22, a threaded section 24 and a nut 26.

In use, the shroud 22 is placed over a nut 28 that has been tightened onto a bolt 30. A portion of the bolt extends beyond the nut and the cover 18 is rotated on the bolt by turning the nut 26 thus screwing the cover 20 onto the bolt 30. The nut could be hexagonal, as shown, or square for instance, or of any other configuration, including a round drive.

Rotation continues until either the end of the bolt 30 abuts an end face 32 of the cover or, alternatively or additionally, until the nut 28 abuts the axially facing surface 34 of the cover (in which case the end face 32 can be omitted to allow the bolt to extend to be at least partially axially coextensive with the nut 26). At that time, further torque inputted to the cover by the nut will result in the nut 26 shearing of the shroud at the location of a narrow neck 36.

The neck 36 is located at the axially outermost region of the threaded section 24 and is defined by exterior surfaces 38 and 40 of the cover that taper inwardly and rearwardly from the shroud and inwardly and forwardly from the unit 26. The angle of the surface 38 to the axial extent of the cover is 380 and the angle of the surface 40 is 45 .

The dimensions of the neck are configured such that shearing occurs at a torque in the region of 80 or 90 Nm.

After shearing, the unit 28 is covered by the shroud 22 and thus the unit 28 is not able to be accessed by a spanner to remove the unit.

The cover shown in Figures 4 and 5 is similar to that previously described in construction, mode of operation and the shearing torque. The axial distance of the end of the unit 26 from the neck and the dimensions of the nut are larger than those of the first embodiment.

The cover 10 is particularly, although not exclusively, applicable to protecting nuts that have been used to secure the head coupling onto the overrun coupling on a vehicle or to secure a ball coupling onto a vehicle.

In such instances, a trailer or caravan can be secured to a ball coupling on a vehicle and, whereas thieves have previously been able to remove the ball coupling and connect it to their own vehicle, they are no longer able to do so when the nuts are protected by the shroud.

The cover is particular easy to make as it can be formed from cheaper material than the bolt 30 and nut 28. Furthermore, the cover can be fitted to existing nuts and bolts.

The cover can be used with standard or self lock nuts which can be torqued to their correct settling prior to these covers being fitted.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A protective cover including a first part arranged, in use to extend at least partially over a fastener, the first part being connected to a second part that is arranged, in use, to cause the first part to be secured in a position at least partially over a fastener, the cover being configured such that the second part is arranged to break off the first part upon application of sufficient force to the second part.

2. A cover as claimed in Claim 1 in which the first part is arranged, in use, to be substantially completely coextensive with the fastener.

3. A cover as claimed in Claim 1 or 2 in which the first part is arranged to be spaced from an outwardly facing surface of a fastener.

4. A cover as claimed in any preceding claim in which the first part is arranged to substantially completely surround a fastener.

5. A cover as claimed in any preceding claim arranged to abut with a fastener to restrict relative movement of the cover with respect to a fastener.

6. A cover as claimed in any preceding claim in which the first part is arranged to abut with a member to which a fastener is secured with such abutment restricting relative movement of the cover and the member to which the fastener is secured.

7. A cover as claimed in Claim 5 or 6 in which one of the abutments is arranged, in use, to provide a reactive force whereby the second part, in use, is arranged to break off the first part.

8. A cover as claimed in any of Claims 5 to 7 in which both of the abutments are arranged, in use, to provide a reactive force whereby the second part, in use, is arranged to break off a first part.

9. A cover as claimed in any preceding claim including a portion of reduced dimensions arranged to form the break between the first and second portions.

10. A cover as claimed in Claim 9 in which the portion of reduced dimensions comprises a narrow cross-section.

11. A cover as claimed in Claim 9 or 10 in which the portion of reduced dimensions is defined by an external surface of the cover that tapers inwardly towards the region that is arranged to break from at least one direction.

12. A cover as claimed in Claims 9, 10 or 11 in which the portion of reduced dimensions is defined by an external surface of the cover that tapers inwardly towards the region that is arranged to break from two opposed directions.

A cover as claimed in Claim 11 or 12 in which the taper or tapers are arranged to extend completely around the cover.

14. A cover as claimed in any preceding claim including a threaded portion arranged, in use, to engage a threaded member on which a fastener is located.

15. A cover as claimed in Claim 14 in which rotation of the cover on the threaded portion is arranged to advance the first part to extend over a fastener.

16. A cover as claimed in any of Claims 14 or 15 in which rotation of the cover on the threaded portion is arranged to advance the first part to extend further over a fastener.

17. A cover as claimed in any of Claims 14 to 16 in which the break in the cover is arranged to occur at the end region of the threaded member.

18. A cover as claimed in any preceding claim in which the second portion is arranged to be engaged by a tool.

19. A cover as claimed in any preceding claim in which the second portion comprises a nut.

20. A cover as claimed in any preceding claim in which the first and second portions are integrally formed.

21. A protective cover substantially as herein described with reference to, and as shown in any of the accompanying drawings.

22. A method of protecting a fastener comprising using a protective cover and causing a first part of the cover to be connected to the fastener by exerting a force on the

second part of the cover with the second part of the cover being broken off upon application of sufficient force to the second part.

23. A method as claimed in Claim 22 comprising indirectly connecting the cover to the fastener.

24. A method as claimed in Claim 23 comprising connecting the cover to a member on which the fastener is also connected.

25. A method as claimed in any of Claims 22 to 24 comprising applying a force to the second part to cause the first part to extend over the fastener.

26. A method as claimed in any of Claims 22 to 25 comprising applying a force to the second part to cause the first part to extend further over the fastener.

27. A method as claimed in any of Claims 22 to 26 comprising causing a force exerted on the second part to be opposed with the reactive force being exerted by abutment of the cover with the fastener.

28. A method as claimed in any of Claims 22 to 27 comprising a force being exerted on the second part with a reactive force being provided by abutment of the cover with a member to which the fastener is connected.

29. A method as claimed in any of Claims 22 to 28 comprising screwing the cover on to the member to which the fastener is connected to cause axial movement of the cover over the fastener.

30. A method as claimed in any of Claims 22 to 29 comprising locating the protective cover over a fastener that is secured to a vehicle.

31. A method as claimed in Claim 30 comprising locating the protective cover over a fastener that secures a ball coupling to a vehicle.

32. A method as claimed in Claim 30 comprising locating the protective cover over a fastener that secures a head coupling on to the overrun coupling of a vehicle.

33. A method of protecting a fastener substantially as herein described with reference to, and as shown in any of the accompanying drawings.

34. A fastener when protected by a protective cover as claimed in any of Claims 1 to 21.

35. A fastener when protected by a method of protection as claimed in any of Claims 22 to 33.