GB2073298A

GB2073298A - Lockable nut or bolt

Info

Publication number: GB2073298A
Application number: GB8010217A
Authority: GB
Original assignee: Dutton & Co Ltd H
Current assignee: Dutton & Co Ltd H
Priority date: 1980-03-26
Filing date: 1980-03-26
Publication date: 1981-10-14
Also published as: GB2073298B

Abstract

A three-part locking nut or bolt assembly, primarily for vehicle wheels, comprising a nut 1, a shroud 4 and a key-operated lock 5, the key-actuated detents 7 on the lock engaging the shroud rather than the nut, and a nose 9 on the lock engages a bolt device, in the form of a spring ring 12, mounted in the nut to hold the shroud in place on the nut. The nut could be replaced by the head of a bolt. <IMAGE>

Description

SPECIFICATION Lockable nut or bolt This invention relates to a nut or bolt assem bly capable of being locked in place to hinder theft of an article secured in place by the nut or bolt. Nuts of this kind are known and are widely used for securing wheels on road vehicles.

One known form of locking wheel nut assembly, forming the subject of British Patent specification No. 1198922, comprises three parts, namely, a nut having the usual hexago nal external shape and a screw-threaded bore, a shroud that fits over the nut to prevent access to the hexagonal surface of the nut, and a detachable key-operated lock which fits into a recess in the end of the nut and has detents which engage annular grooves in the wall of the recess to secure the lock to the nut, whilst a shoulder on the lock holds the shroud in place.

Another previously proposed anti-theft nut assembly for vehicle wheels forms the subject of British Patent Specification No. 310932 and again comprises three parts, namely a nut, a shroud and a lock. The lock fits permanently into a recess in the end of the nut and, on rotation ot the lock barrel, it displaces a radial locking pin mounted in the nut, to move the pin outwards to engage a shoulder on the inside wall of the shroud. A nut is also known in which a magnetic key withdraws a catch to allow the user to turn a member to disengage detents that lock the shroud to the nut.

The aim of the present invention is to provide a particularly neat and simple form of locking nut assembly of this same general kind, reliable in operation and attractive in appearance. Although primarily applicable to nuts, the invention is equally applicable to protecting the head of bolts. According to the invention we propose that the lock should be mounted in the shroud and have detents that secure it to the shroud, and that a formation on the body of the lock should, when the lock and shroud are assembled onto the nut or the head of the bolt, act on keying means that key the nut or the head of the bolt directly to the shroud, i.e. not through the intermediary of the lock.

In a preferred version the formation on the lock comprises a nose or boss that enters a recess in the end of the nut or bolt head to deflect radially outwards a detent device, mounted in the nut or bolt head, to cause the detent device to move radially outwards to engage a groove or shoulder on the inside of the shroud.

The detent device is preferably in the form of a ring-shaped wavy spring, a portion of which projects into the recess and, when engaged by the formation the lock, it distorts the spring to cause another portion of it to project radially outwards to engage the groove or shoulder in the shroud.

An example of a locking nut assembly in accordance with the invention is illustrated in the accompanying drawings, in which: Figure 1 is an axial section through the nut assembly; Figure 2 is a section on the line 2-2 in Fig.

1 with the lock and shroud absent; and Figure 3 is a section on the same line, but with the lock and shroud in place, as in Fig.

1.

In the assembly illustrated, a nut 1 has the usual internal screw thread 2 and external hexagonal surface 3 for engagement by a spanner. This surface is covered by the lower end of a hollow cylindrical shroud 4, the upper end of which contains a key-operated barrel lock 5. Annular grooves 6 in the inside surface of the upper part of the shroud 4 are engaged by radially moving spring-loaded pins 7, and the pins are only withdrawn, to release the lock from the shroud, by insertion of the correct key, indicated diagrammatically at 8.

A rounded nose 9 on the lower end of the lock 5 enters a recess 10 in the upper end of the nut and, in doing so, deflects outwards two opposed inwardly projecting portions 11 (see Fig. 2) of a ring-shaped spring 1 2 which is mounted in a pair of slots in the wall of the recess. This causes an intermediate portion 1 3 of the spring to project outwards beyond the periphery of the upper portion of the nut, so that it engages behind a shoulder 1 4 formed inside the shroud, and thereby forms a detent device, holding the shroud in place on the nut as long asthe nose 9 of the lock is engaged in the recess 10 in the nut.

To release the shroud it is necessary to insert the key 8, withdrawing the pins 7 from the grooves 6, and so allowing the lock to be withdrawn axially from the shroud. This allows the spring 1 2 to revert to its rest position, clear of the shoulder 14, and the shroud can then be removed, giving access to the nut.

The lock can then be replaced in the shroud and, if desired, the key can be withdrawn, which will cause the lock to be retained in the shroud and reduce the risk of these separate components being lost.

It will be understood that the principle of the invention could be applied without the nut necessarily being hexagonal. The only essential thing is that it has some sort of noncircular external surface engageable by a spanner or other torque applying device, and capable of being shielded by the shroud. Also the nose on the lock could be replaced by some other formation which, when the shroud and lock are engaged with the nut, acts-on the spring 1 2. Indeed the spring could be replaced by another equivalent form of detent device that is capable of being engaged by the nose (or other formation) on the lock and moved out into the path of the shroud to prevent removal of the latter. Finally, as indicated earlier, the nut could be replaced by the head of a bolt, or a so-called sleeve bolt, which is an alternative form of combined nut and bush sometimes used in securing vehicle wheels. Furthermore, although the invention is primarily applicable to preventing theft of wheels of road vehicles, it could find use elsewhere.

Claims

1. A locking nut or bolt assembly comprising a nut or bolt head having an an external non-circular surface for engagement by a spanner or other torque-applying device, a hollow shroud adapted to fit over the nut or bolt head to prevent access to that surface, and a lock receivable in but detachable from the shroud, the lock having key-released detent means that key it to the shroud and having a formation which, when the lock is in the shroud and the shroud is fitted over the nut or the bolt head, acts on a radially movable detent device mounted in the nut or the bolt head to move that detent device outwards to prevent removal of the shroud from the nut or the bolt head.

2. A locking nut or bolt assembly according to claim 1 in which the lock is a barrel lock and the formation on the lock is a nose which enters a recess in the nut or bolt head and engages the detent device which partially protrudes into that recess.

3. A locking nut or bolt assembly according to claim 1 or claim 2 in which the detent device comprises a spring ring mounted in the nut or the bolt head, a portion of the ring being engaged by the formation on the lock to distort the shape of the ring such that another portion of its projects into the path of a shoulder on the shroud to achieve the said prevention of removal of the latter.

4. A locking nut or bolt assembly substantially as described with reference to the accompanying drawings.