GB2478923A

GB2478923A - Removable locking bolt

Info

Publication number: GB2478923A
Application number: GB201004794A
Authority: GB
Inventors: Mark Andrew Curtis
Original assignee: Sas SECURITY PRODUCTS Ltd
Current assignee: Sas SECURITY PRODUCTS Ltd
Priority date: 2010-03-23
Filing date: 2010-03-23
Publication date: 2011-09-28
Also published as: GB201004794D0

Abstract

A locking bolt 1 for reception in a lock holder 3 comprises a key-operated bolt which is slidable within the lock holder, the bolt comprising a cylindrical barrel 10 which contains a camming surface 16 and includes at least one hole 20 containing a captive rotatable ball latch 21 in contact with the camming surface 16. The bolt is inserted in to the lock holder and the cam is operated by rotating the key to push the ball in to a detent formed on the inner surface of the lock holder to prevent movement of the locking bolt.

Description

REMOVABLE LOCKING BOLT

TECHNICAL FIELD OF THE INVENTION

This invention relates o removable locking bofts.

BACKGROUND

Q Removable locking bofts are often used o secure items against L() unauhorised removal or theft. Examples of such items include Q wheel clamps and hichlocks for caravans and trailers, although these examples should no be regarded as exhaustive. The locking boft co-operates with an opening which is provided for the purpose in part of the item, referred o generally herein as a lock holder. When the locking boft is fitted in the lock holder the bole prevents wo or more components from moving relative o each other so that the item cannot be removed. However, when the locking boft s released from the lock holder the components are allowed o move, thereby freeing the item.

Locking bofts are normally operated by means of a key. When the correct key is inserted, spring-loaded Iaching pins can be withdrawn allowing the locking bolt to be freely inserted into and withdrawn from the lock holder, but when the key is removed the latching pins project, under spring loading, to engage an undercut or groove in the lock holder and thereby securely retain the locking bolt within the holder.

Locking bolts are designed to be difficult and time-consuming to remove using drills or specialist tools, but nevertheless, many existing locking bolts are susceptible to attack by slide-hammers, drills or just brute force.

The present invention seeks to provide a new and inventive form of locking bolt which less susceptible to unauthorised removal than known locking bolts.

14) SUMMARY OF THE INVENTION

The present invention proposes a locking bolt for reception in an opening in a lock holder provided with an undercut or recess, the locking bolt comprising a cylindrical barrel which contains a cam member and a locking mechanism operable by a key inserted through a key aperture at a proximal end of the barrel to rotate the cam member about the axis of the barrel, and the barrel contains at least one hole containing a captive rotatable ball latch which can be moved by the cam between a projecting position and a retracted position.

Ball latches provide secure retention of the locking bolt within the lock holder, and their ability o roae makes the locking boft less susceptible o attack by slide-hammers, drills and the like.

The ball latch or latches may be held captive by a small inwardly-directed lip a the outer end of the hole.

In a preferred arrangement the key can only be removed from the locking boft when the or each ball larch is in the projecting position, thus ensuring that the key is no inadverenly removed with the ball larch or latches reraced.

The locking boft preferably has a plurality of ball latches arranged a circumferential intervals.

The invention includes the locking boft in combination with a lock holder having an opening for the locking boft provided with an undercut or recess for receiving the ball latch or latches.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred o therein are included by way of non-limiting example in order o illusrae how the invention may be pu into practice.

In the drawings: Figure 1 is an axial section through a locking boft and lock holder in accordance with the invention, with the locking bolt shown in the latched condition; Figure 2 is an enlarged detail of the locking bolt; Figure 3 is a transverse section through the locking bolt and lock holder on the plane Ill-Ill of Fig. 1; Figure 4 is a similar view to Fig. 1 but showing the locking bolt in the unlatched condition; Figure 5 is a similar view to Fig. 4 showing the locking bolt being removed from the lock holder; and Figure 6 is a modified form of the locking bolt and lock Q holder showing the locking bolt being inserted. L()

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, a locking bolt 11 which is operable by a key 2 is removably received in a lock holder 3. The lock holder may be a component of an item such as a wheel clamp or hitchlock which is secured against removal or tampering when the locking bolt is inserted, in a manner which is already known to those skilled in the art and will not therefore be described further.

The locking bolt 1 includes a cylindrical barrel 10 with axis A. At a proximal end of the locking bole, the barrel 10 is partially closed by an integral annular wall 11 containing a central key aperture 12 which is just large enough o accommodate the key 2. The locking bole is assembled from the distal end so that the components cannot be removed from the proximal end which is exposed in use. Saring a the proximal end, the barrel 10 contains an anti-drill disc 14 which is aperwred o receive the key 2, a locking assembly 15, a cam member 16, and an end plug 17 which is secured in the distal end of the barrel by means of screw threads, splines, grub screws or such like. When engaged by a roaing drill, the anti-drill disc 14 is freely roaable within the barrel o prevent the locking assembly 15 from being destroyed by drilling.

The wall of the barrel 10 contains a pair of diametrically opposed radial bores 20 which are axially positioned o co-operate with the cam member 16. Each bore 20 contains a spherical ball latch 21 which, as shown in the enlarged detail of Fig. 2, is held captive within the respective bore by a small inwardly-directed lip 22 a the outer end of the bore (shown exaggerated for purposes of illusraion). The key 2 can only be removed from the lock when the cam is in the position shown in Fig.s 1 and 3, in which the ball latches are urged half-way ou of the bores by the outer cam surface 23 of he cam member. This consiWes the latched condition of the locking boft. In this position the balls are, nevertheless, free o roae within the bores 20. When the correct key is inserted, the cam member 16 can be roaed through 90 degrees o the position shown in Fig. 4, 50 that the latching balls retract into a pair of diametrically opposed peripheral recesses 24 in the outer surface of the cam member (see Fig. 3 also). In this position, the key cannot be withdrawn and must remain within the locking bolt.

Referring to Fig. 5, the lock holder 3 contains a cylindrical opening 30, the diameter of which is just sufficient to receive the barrel 10 of the locking bolt as a close sliding fit, with the key 2 inserted and the ball latches retracted. The wall of the lock holder contains a continuous annular groove 31 (see Fig. 3 also) which is positioned to co-operate with the ball latches 21 such that when the key is rotated to the latching position the balls project into the groove 31 before the key can be removed.

The ball latches thus act to firmly retain the locking bolt within the lock housing. L()

Due to the fact that the balls can rotate freely even in their latching positions, the latches exert very little frictional resistance against the lock housing and it is therefore extremely difficult to remove the locking bolt by drilling or using a slide-hammer for example. The locking bolt simply spins within the lock housing.

In order to remove the locking bolt the key 2 must be inserted and rotated to allow the ball latches to retract, so that the key can then be used to withdraw the locking bolt from the lock housing.

Both the locking bolt and the lock holder may be modified depending upon the particular application. For example, Fig. 6 shows a modified form of the locking boft in which a "bullet end" extension 40 is screwed into the end plug 17 o project through an aperture 41 a the inner end of the lock holder 3 when the locking boft is fully inserted.

Although the most secure arrangement is o use a plurality of ball latches positioned a equal circumferential intervals around the latch, i would still be possible o achieve effective latching with a single ball larch. Furthermore, larger diameter latching bofts may accommodate a larger number of circumferenially arranged ball latches.

Q Whilst the above description places emphasis on the areas which are believed o be new and addresses specific problems which have been identified, i is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

* * * * * * * *

Claims

CLAIMS1. A locking boft for reception in an opening in a lock holder provided with an undercut or recess, the locking bole comprising a cylindrical barrel which contains a cam member and a locking mechanism operable by a key inserted through a key aperWre a a proximal end of the barrel o roae the cam member about the axis of the barrel, and the barrel contains a lease one hole containing a captive roaable ball larch which can be moved by the cam between a projecting position and a reraced position.

(Y)
2. A locking boft according o Claim 1 in which the ball latch or latches are held captive by a small inwardly-directed lip a the outer end of the hole. (\J
3. A locking boft according o Claim 1 or 2 in which the key can only be removed from the locking bolt when the or each ball latch is in the projecting position.
4. A locking boft according o any preceding claim in which the locking boft has a plurality of ball latches arranged a circumferential intervals about the axis of the barrel.
5. A locking boft according o any of Claims 1 o 4 in combination with a lock holder having an opening for he locking bole provided with an undercut or recess for receiving the ball Iach or Iaches.
6. A locking boft subsanially as described with reference o the drawings.* * * * * * * * C') (\J