GB2325697A

GB2325697A - Locking device with attack protection

Info

Publication number: GB2325697A
Application number: GB9809205A
Authority: GB
Inventors: Yurek Wronski
Original assignee: Regent Lock Co Ltd
Current assignee: Regent Lock Co Ltd
Priority date: 1997-05-29
Filing date: 1998-04-29
Publication date: 1998-12-02
Anticipated expiration: 2018-04-29
Also published as: GB2325697B; GB9711108D0; GB9809205D0

Abstract

The invention relates to a locking device for locking a member 11 such as a door in position, the device comprising a latch mechanism 21 for mounting on one side of the member 11, a security device 31 for restricting the operation of the latch mechanism to authorised users, and means 41 operable independently of the operation of the security device 31 for locking the latch mechanism against operation to unlock said member. Withdrawal of the security device from the said opposite side of the member 11 removes projection 42 - allowing means 41 to slide downwards to prevent latch mechanism operation.

Description

LOCKING DEVICE This invention relates to a locking device which comprises a security device and a latch mechanism, the latch mechanism being operable only by authorised users of the security device. It is concerned with the problem of preventing an unauthorised operator removing part of the locking device in order to bypass the security device, thereby being able to cause the latch mechanism to operate.

According to the invention there is provided a locking device for locking a member in position, the device comprising a latch mechanism for mounting on one side of the member to be locked for locking said member in position, a security device for mounting on the opposite side of the member to be locked for restricting the operation of the latch mechanism to authorised users, means operable independently of the operation of the security device for locking the locking mechanism against operation to unlock said member, said means being operable by withdrawal of the security device from said opposite side of said member.

An example of the invention will now be described with reference to the accompanying drawings in which Figure 1 is a front elevation of a locking device with its cover removed, Figure 2 is a section on line A - A in Figure 1 and Figure 3 is a rear elevation of the locking device of Figure 1.

As can be seen in Figure 2, a member 11 to be locked, such as a garage door, has a locking device mounted thereon with front and rear plates 12, 13 mounted on opposite sides of the door. The plates are secured together by bolts 14 passing through apertures 15 in the rear plate being screwed into threaded studs 16 in the rear of the front plate, the studs fitting into apertures drilled in the door. The rear plate 13 is also secured to the rear of the door by screws in further apertures 17 engaging the door itself.

The rear plate 13 has mounted thereon a latch mechanism 21 which controls a latch on the door engaging a fixed plate to lock the door in position.

These latter components are conventional and are not shown in the drawings.

The latch mechanism is turned by rotating a square section shaft 22 passing through the door and operable by a handle 23 mounted on the front plate 12.

The mechanism has a disc 24 rotatable with the shaft, the disc having two cutout portions 25, 26. The upper cut-out portion 25 engages a fixed stop 27 which limits the rotation of the disc (and hence of the shaft) to about 90". The lavt-out portion receives a vertically reciprocable member 28 at the upper limit of its stroke.

The front plate has below the handle 23 a key operated lock 31. The lock 31 has a connecting member (not shown) passing through an aperture in the door to a cam 32 mounted on the rear 13 plate. The lower end of the member 28 is tapered to a nose 29 which acts as a follower for the cam 32.

As the lock 31 is operated by its key, the cam rotates to move the member 28 into and out of engagement with the lower cut-out portion 26 of the disc. The cam surface has two small indentations 33, 34 for the nose at the compositions corresponding to the locked and unlocked positions of the lock respectively.

A second vertically reciprocable member 41 is provided on the rear plate. The second member 41 is normally supported at the upper end of its stroke by a pin 42 mounted on the rear of the front plate 12 and extending through an aperture in the door. If the pin 42 is removed, the second member 41 can fall to the bottom of its stroke where it engages a shoulder 43 on the cam 32 in its position corresponding to the locked position of the lock 31 to prevent the cam 32 being rotated to the position corresponding to the unlocked position of the lock.

In normal operation, the locking device can be operated to unlock the door by using the key to rotate the cam 32 so as to allow the first member 28 to move downwards, thus releasing the disc 24 for rotation. The handle 23 can then be turned to operate the latch mechanism 21 to remove its latch from the fixed plate, thus allowing the door to be opened.

When the door has been closed again, the handle 23 and latch are returned to their original positions, either by the operator or by springs in the conventional manner. When the handle 23 is in its original position the lock can be locked, thus rotating the cam 32 to raise the first member 28 into the second cut-out 26 in the disc 24 which has been realigned therewith by the return of the handle to its original position.

An unauthorised user may attempt to rotate the cam by removing the protecting key-operated lock 31 and the front plate 12. The aperture through the door through which the turning lever connects the key operated lock to the cam will then allow the user to use that lever or insert another suitable lever (or finger) to rotate the cam 32 and release the square-section shaft 22 for rotation. The provision of the second member 41 prevents such release because as soon as the front plate 12 is removed from the door, its pin 42 ceases to support the second member 41 which falls into engagement with the shoulder 43 on the cam to prevent its rotation. The shaft 22 thus remains locked against rotation by the first member 28 remaining in its upper position.

The key for operating the lock can be of any suitable type, including a series of push-buttons which must be arranged in a suitable pattern to allow operation of the lock, a magnetic strip on a card or a coded signal transmitted by electromagnetic radiation.

Claims

CLAIMS:

1. A locking device for locking a member in position, the device comprising a latch mechanism for mounting on one side of the member to be locked for locking said member in position, a security device for mounting on the opposite side of the member to be locked for restricting the operation of the latch mechanism to authorised users, means operable independently of the operation of the security device for locking the latch mechanism against operation to unlock said member, said means being operable by withdrawal of the security device from said opposite side of said member.

2. A locking device according to claim 1, the latch mechanism being rotatably actuable.

3. A locking device according to claim 2, the latch mechanism comprising a rotatable shaft.

4. A locking device according to claim 2 or claim 3, the security device being adapted to substantially inhibit rotation in the latch mechanism in a secured position of the device.

5. A locking device according to claim 4, the security device including a reciprocable member.

6. A locking device according to claim 5, the security device including a cam, operable by means of a barrel lock, the cam acting upon the reciprocable member to lock or unlock the device.

7. A locking device according to any preceding claim, the independent locking means being operable by force of gravity upon withdrawal of the security device.

8. A locking device according to any preceding claim, the independent locking means being inaccessible from the said opposite side of the member.

9. A locking device according to any preceding claim, the independent locking means acting via the security device for locking the latching mechanism against operation.

10. A locking device according to claim 6, the independent locking means acting upon the cam of the security device.

11. A locking device, substantially as hereinbefore described with reference to the accompanying drawings.

12. A door, including a locking device according to any of claims 1 to 11.