GB2261700A

GB2261700A - Dead bolt for a lock

Info

Publication number: GB2261700A
Application number: GB9223278A
Authority: GB
Inventors: Brian E Cowper
Original assignee: Banham Patent Locks Ltd
Current assignee: Banham Patent Locks Ltd
Priority date: 1991-11-20
Filing date: 1992-11-06
Publication date: 1993-05-26
Anticipated expiration: 2012-11-06
Also published as: GB2261700B; GB9124561D0; GB9223278D0

Abstract

A lock has a dead bolt comprising a member (8) formed from the solid which provides a bolt head (10), a lath (12) having a wall thickness less than the thickness of the bolt head and a flange element (14) extending over the bolt lath from the bolt head to increase the resistance of the lath to lateral forces such as might be experienced from an attempt to force the lock. The lath and flange member have a sliding fit between opposite faces of the casing so that the casing also contributes to the strength of the lock against a forced entry. For further reinforcement, the bolt may have another flange element (16) extending from the bolt head and lath and incorporating a stump (18) for a locking mechanism. <IMAGE>

Description

LOCKS This invention relates to dead bolting locks, in particular, although not necessarily exclusively, keyoperated locks.

According to the present invention there is provided a lock comprising a dead bolt which includes a bolt head, a bolt lath having a wall thickness less than the thickness of the bolt head, and a flange element extending over at least a part of the length of bolt lath from the bolt head and providing an increased resistance of the lath against forces applied to the bolt head transverse to its plane of movement.

Preferably said flange element extends from the bolt head, and it can also be an advantage to form the bolt head, lath and flange element as an integral member from the solid.

By these means it is possible in a reasonably simple and inexpensive way to increase significantly the resistance of the dead-bolted lock to forced opening, eg.

by a jemmy.

Preferably, the lath and flange element have a sliding fit between opposite faces of a casing of the lock within which the bolt is mounted. The strength of the casing is then able to make a greater contribution to the resistance of the lock to jemmying.

It is also preferred to provide the bolt with an integral stump formed on a further flange element conjoined to the bolt head and lath. When these are formed integrally the further flange element may also be formed as an integral part of the bolt.

The first flange element may project beyond the height of the bolt head if this is required to increase the strength of the bolt. It will often be preferred also, for compactness of design, to arrange that the flange element extends over at least a part of the length of the operating mechanism, eg. a lever mechanism, for the key operation of the bolt.

An example of the invention is illustrated in the accompanying drawings, wherein: Fig. 1 is an exploded oblique view of a deadlock according to the invention, Fig. 2 is a side view of the lock of Fig. 1 with the casing front plate removed, and Figs. 3 to 5 are, respectively, side, rear and bottom plan views of the bolt employed in the lock of Figs. 1 and 2.

The drawings illustrate a mortice lock having a key operated lever mechanism 2 in a casing 4 which can be fitted into a mortice slot in a door (not shown) to place forends 6 of the lock flush with the edge face of the door. A bolt 8 mounted within the casing can be slid out by the lever mechanism to project from the door into a keeper (not shown) in the door jamb.

The bolt 8, which is formed integrally from a single block, comprises a bolt head 10, a thin-walled backplate or lath 12 having its back face coplanar with the back face of the bolt head, and a top flange 14, the rear face of which is also coplanar with the rear face of the bolt head but which is the same thickness as the bolt head. The top flange 14 extends over the length of the lath 12 and it projects above the height of the bolt head 10 while being rigid with the bolt head by virtue of a deeper leading portion 14a forming a fillet with the bolt head.

Parallel to the top flange, the bolt has a further flange element 16 which includes a stump 18 and a reduced thickness portion 20. These elements are designed to operate in known manner as detainers for the levers of the mechanism 2.

The bolt 8 is guided for sliding movement in the casing by the location of the bolt head 10 in corresponding slots 22 in the forends 6, and by a pin 24 fixed to the casing back plate 26 and located in a slot 28 in the bolt lath. The length of the slot determines the limit of the sliding movement.

A wedge-like recess 30 in the bottom edge of the bolt lath is entered by a pin 32 projecting from the rear face of a driver plate 34 mounted on a key shaft 36 which is rotatably supported in the front and rear plates 26,38 of the casing. The plate 34 and shaft 36 are slotted to receive a key, which is provided with appropriate wards for operating the lock lever mechanism 2 in known manner as the key is rotated, the rotation of the plate 34 with the key also bringing the pin 32 into the recess 30 to cam the bolt outwards or inwards.

A feather spring 42 mounted on a fixed pin 44 engages a step 46 on the driver plate 34 to locate the plate with the key slot vertical and in register with corresponding slots in the front and back plates of the casing in both the bolt-extended and bolt-retracted positions.

Two further pins 48,50 project from the back plate of the casing 4 and are accommodated by clearance slots in the bolt lath, the first serving as a pivot pin for the levers of the lock mechanism 2 and the second as an abutment for the lever springs of that mechanism so that the levers are being urged downwards onto the bolt stump 18 to lock the bolt in position. The pins 48,50 project through and are supported in holes in the casing front plate 38 which is secured by screws run into threaded bores in the spring pivot pin 44 and two further pins 52,54, projecting from the back plate. All three pins 44,52,54 bear against the rear face of the casing front plate. The front plate is thereby located so that the bolt head 10 and top flange 12 have only enough clearance between the front and rear faces of the casing interior to allow the bolt to slide freely.

In use, the integral bolt head, top flange and lath form an essentially rigid member resisting deformation by a jemmy. Furthermore, as far as concerns any such forces transverse to the plane of movement of the bolt, this rigid member also forms a substantially rigid structure with the casing to further reinforce the stiffness of the construction, which results not only from the engagement of the bolt head in the forend slots but also the relatively small clearance the bolt head and top flange have with the front and rear plates of the casing.

The overall construction of the lock nevertheless remains relatively simple and it is possible to employ mainly standard components.

Claims

1. A lock comprising a dead bolt which includes a bolt head, a bolt lath having a wall thickness less than the thickness of the bolt head, and a flange element extending over at least a part of the length of the bolt lath from the bolt head and providing an increased resistance of the lath against forces applied to the bolt head transverse to its plane of movement.

2. A lock according to claim 1 wherein said flange element extends from the bolt head.

3. A lock according to claim 1 or claim 2 wherein the bolt head, lath and flange element are formed as an integral member from the solid.

4. A lock according to any one of the preceding claims wherein the lath and flange element have a sliding fit between opposite faces of a casing of the lock within which the bolt is mounted.

5. A lock according to any one of the preceding claims wherein the bolt has an integral stump formed on a further flange element conjoined to the bolt head and lath.

6. A lock according to claim 5 wherein the further flange element is formed as an integral part of the bolt.

7. A lock according to any one of the preceding claims wherein the first flange element projects beyond the height of the bolt head.

8. A lock according to any one of the preceding claims wherein the flange element extends over at least a part of the length of an operating mechanism for the key operation of the bolt.

9. A lock constructed and arranged for use and operation substantially described herein with reference to the accompanying drawings.