GB2133491A - Security nuts - Google Patents

Abstract

A security nut comprises a hexagonal sided head (2) connected to a body portion (1) by a frangible neck (3) of reduced diameter. On tightening up past a given torque head (2) breaks off or may be snapped off to prevent the body portion (1) being removed. Further security is imparted by rotatable collar (6) which prevents purchase by a wrench on the body portion.

Description

SPECIFICATION Security nuts This invention relates to nuts which may be threadedly engaged with bolts, studs orthe liketo form part of ortho secure a security installation, closure or the iike.

In the past, nuts have often been a weak link in security because with the right spanner or a suitable wrench a miscreant has been able to breach the security. There have been examples of cash boxes bolted to the floor of commercial vehicles by headless bolts. Secure enough from inside the vehicle, but all a thief has to do is to undo the corresponding nuts from beneath the vehicle and remove the bolts and make off with the box. One attempt to prevent the removal of nuts are the key lockable nuts sometimes used to preventthe theft of wheels from automobiles. These however are expensive for regular security use and are in any case not too difficultto breach.

What is required is a nut which once tightened can be made permanently irremovable from its threaded shank, and the object of this invention is to provide such a nut.

According to the invention there is provided a security nut comprising an annular body portion having a central shank receiving threaded bore therein,and atighteningtool engageable head portion connected to the body portion by a readily frangibletorquetransmittableintermediate portion.

Thus the nut may be tightened in the usual way by engaging a tightening tool with the head portion.

Tightening torque is transmitted to the body portion by the intermediate portion, and once the required tightness is achieved the head portion may be snapped, cut or otherwise broken off leaving only the annular body portion remaining. Thiswill afford no purchase to an intending remover making it permanently extremely difficult if not impossible to remove the nut.

The purchase available can be reduced still further in a preferred embodiment by providing a rotatable collar around the body portion. Thus any purchase that may be effected by a wrench can only result in the futile spinning ofthe collar around the body portion which remains firmly irremovable. Ball or roller bearings, or other friction reducing means such a grease packed fibre washers may be provided between collar and main body to reduce friction while supportingthecollaragainstdeformation.

The intermediate frangible portion could comprise a plurality of integral bridges between the othertwo portions, but I provide preferably a reduced diameter neck of sufficient strength to transmit the tightening torque, yet readily rupturable byforexample a saw bladeora blowfrom a cold chisel.

In order that the invention may be readily understood an embodimentthereofwill now be described byway of example with reference to the accompanying drawing which shows a section through a nut of the invention.

The nut comprises an annular body portion 1 connected to a hexagonal sided head portion 2 by a reduced diameter neck portion 3. The body portion has a central threaded bore 4 for receiving the shank of a a bolt or stud and the head portion is formed with a coaxial bore of somewhat greater diameter to allow removal ofthe head portion from the exposed end if any ofthe shank.

Around the main body is disposed a rotatable collar 6 of hardened steel retained thereon by an inwardly directedflange7. Thisflange engages in an annular ledge 8 whose axial depth is greaterthan the axial thickness of the flange 7 to remit ready rotation. A metal washer 9 is provided to preventthe inner end 10 ofthe nut penetrating the abutting for example wooden surface and causing the collar to foul therewith.

In use the nut is tightened up in the configuration shown and then the head portion 2 is removed by cutting orotherfracture ofthe intermediate portion 3 to leave onlythe rotatable collar clad body portion exposed which cannot be rotated by a tool and is therefore irremovable and secure.

CLAIMS (Filed on 21 March 1983) 1. Asecurity nut comprising an annular body portion having a central shank receiving threaded boretherein, and a tightening tool engageable head portion connected to the body portion by a readily frangibletorquetransmittable intermediate portion.

2. A security nut according to claim 1 having a rotatable collar around the body portion.

3. A security nut according to claim 2 including friction reducing means between the collar and body portion to reduce friction while supporting the collar against deformation.

4. Asecurity nut according to claim 2 or3 in which the collar is retained on the body portion by an inwardly directed flange.

5. A security nut according to any of the preceding claims wherein the intermediate frangible portion comprises a reduced diameter neck.

6. A security nut according to any of the preceding claims in which the head portion is hexagonal sided.

7. A security nut substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   SPECIFICATION Security nuts This invention relates to nuts which may be threadedly engaged with bolts, studs orthe liketo form part of ortho secure a security installation, closure or the iike.

   In the past, nuts have often been a weak link in security because with the right spanner or a suitable wrench a miscreant has been able to breach the security. There have been examples of cash boxes bolted to the floor of commercial vehicles by headless bolts. Secure enough from inside the vehicle, but all a thief has to do is to undo the corresponding nuts from beneath the vehicle and remove the bolts and make off with the box. One attempt to prevent the removal of nuts are the key lockable nuts sometimes used to preventthe theft of wheels from automobiles. These however are expensive for regular security use and are in any case not too difficultto breach.

   What is required is a nut which once tightened can be made permanently irremovable from its threaded shank, and the object of this invention is to provide such a nut.

   According to the invention there is provided a security nut comprising an annular body portion having a central shank receiving threaded bore therein,and atighteningtool engageable head portion connected to the body portion by a readily frangibletorquetransmittableintermediate portion.

   Thus the nut may be tightened in the usual way by engaging a tightening tool with the head portion.

   Tightening torque is transmitted to the body portion by the intermediate portion, and once the required tightness is achieved the head portion may be snapped, cut or otherwise broken off leaving only the annular body portion remaining. Thiswill afford no purchase to an intending remover making it permanently extremely difficult if not impossible to remove the nut.

   The purchase available can be reduced still further in a preferred embodiment by providing a rotatable collar around the body portion. Thus any purchase that may be effected by a wrench can only result in the futile spinning ofthe collar around the body portion which remains firmly irremovable. Ball or roller bearings, or other friction reducing means such a grease packed fibre washers may be provided between collar and main body to reduce friction while supportingthecollaragainstdeformation.

   The intermediate frangible portion could comprise a plurality of integral bridges between the othertwo portions, but I provide preferably a reduced diameter neck of sufficient strength to transmit the tightening torque, yet readily rupturable byforexample a saw bladeora blowfrom a cold chisel.

   In order that the invention may be readily understood an embodimentthereofwill now be described byway of example with reference to the accompanying drawing which shows a section through a nut of the invention.

   The nut comprises an annular body portion 1 connected to a hexagonal sided head portion 2 by a reduced diameter neck portion 3. The body portion has a central threaded bore 4 for receiving the shank of a a bolt or stud and the head portion is formed with a coaxial bore of somewhat greater diameter to allow removal ofthe head portion from the exposed end if any ofthe shank.

   Around the main body is disposed a rotatable collar

   6 of hardened steel retained thereon by an inwardly directedflange7. Thisflange engages in an annular ledge 8 whose axial depth is greaterthan the axial thickness of the flange 7 to remit ready rotation. A metal washer 9 is provided to preventthe inner end 10 ofthe nut penetrating the abutting for example wooden surface and causing the collar to foul therewith.

   In use the nut is tightened up in the configuration shown and then the head portion 2 is removed by cutting orotherfracture ofthe intermediate portion 3 to leave onlythe rotatable collar clad body portion exposed which cannot be rotated by a tool and is therefore irremovable and secure.

   CLAIMS (Filed on 21 March 1983) 1. Asecurity nut comprising an annular body portion having a central shank receiving threaded boretherein, and a tightening tool engageable head portion connected to the body portion by a readily frangibletorquetransmittable intermediate portion.
2. 2. A security nut according to claim 1 having a rotatable collar around the body portion.
3. 3. A security nut according to claim 2 including friction reducing means between the collar and body portion to reduce friction while supporting the collar against deformation.
4. 4. Asecurity nut according to claim 2 or3 in which the collar is retained on the body portion by an inwardly directed flange.
5. 5. A security nut according to any of the preceding claims wherein the intermediate frangible portion comprises a reduced diameter neck.
6. 6. A security nut according to any of the preceding claims in which the head portion is hexagonal sided.
7. 7. A security nut substantially as hereinbefore described with reference to the accompanying drawings.