GB2125093A

GB2125093A - Security lock

Info

Publication number: GB2125093A
Application number: GB08222482A
Authority: GB
Inventors: W J Hollins
Original assignee: Castell Safety International Ltd
Current assignee: Castell Safety International Ltd
Priority date: 1982-08-04
Filing date: 1982-08-04
Publication date: 1984-02-29
Also published as: GB2125093B

Abstract

A tumbler lock comprising a housing 11, a spigot 12 with an integral cage 13 rotatably mounted in the housing 11 and six pins 14 slidably located in the cage 13. The housing 11 has six studs 19 which project between the pins 14 to prevent rotation of the spigot 12. The pins have detents 26 at different positions so that when the correct key 21 is applied to the lock, the pins 14 are all depressed by the appropriate distance, by means of depressions 27 in the key, and the detents 26 register with the studs 19 allowing rotation of the spigot 12. <IMAGE>

Description

SPECIFICATION Security lock The present application relates to security locks and is particularly concerned with radial pin tumbler locks. These locks may be used on doors or indeed many other situations in which known security locks are employed.

A convention radial pin tumbler lock has two sets of pins which are housed in two independent cages. The front pins are of differing lengths and in the locked position, the rear pins extend into the front cage. When the correct key is fitted, the two sets of pins are pushed back until the break between the two sets of pins aligns with the split line between the two cages. The front cage can then turn relative to the rear cage which remains fixed.

This construction suffers from the disadvantage that a high degree of accuracy is required to ensure firstly that all the pins align on the split line and secondly that when the key is removed, all the rear pins spring back into the front cage. It has been found that, in practice to achieve this accuracy, the lock must be finished by hand.

It is an object of the present invention to provide a lock which does not require to be finished by hand.

It is a further object to provide a lock which is less prone to jamming than conventional radial pin tumber locks.

It is a further object to provide a lock which is capable of a great number of changes.

Accordingly to the present invention there is provided a security lock comprising a housing, a spigot, a cage and a plurality of pins, in which the pins are slidably located in the cage, the cage is rotationally fixed with respect to the spindle and has means for engaging a key, the spindle is rotatably located within the housing, the housing has means for engaging the pins thereby preventing the pins, cage and spigot rotating relative to the housing and in which the pins are each slidable through a pre-determined distance to a position in which they do not engage the engagement means, whereby, when the correct key is fitted to the lock, the pins are each moved through their respective predetermined distances, and the pins, cage and spigot may be rotated relative to the housing.

In such a construction, high accuracy of pin length may be avoided so that the manufacture may simply be a machining operation. Also, the positioning of the pin locations in the cage may be less critical. Furthermore, the pin length to diameter ration may be superior to the known construction and so the lock may be less prone to jamming.

The lock of the present invention may also have the advantage that since the spigot need not pass through a second cage, its diameter is not so limited and it may therefore be inherently stronger. For the same reason the lock of the invention has only a single leakage path compared with two in the case of the known construction and so may require only a single seal on the spigot.

The cage and spigot are preferably integrally formed. The means engaging the pins may comprise fixed pins, spigots, splines or balls or any other suitable protrusion but preferably comprise a plurality of studs extending radially inwards further than the radially outward extent of the pins, and each pin has a detent at a position which corresponds to the predetermined distance through which the pin is arranged to slide, the detent being such as to allow the pin to rotate past the stud.

Preferably each pin is slidable against the force of a spring. The means for engaging the key may be a hexagonal head arranged to mate with a corresponding recess in the key.

The invention may be carried into practice in various ways and one embodiment will be described by way of example with reference to the accompanying drawings in which: Figure 1 is a partial axial section through a lock in accordance with the invention, and Figure 2 is a front view of the lock of Figure 1.

The lock includes a housing 11, a spigot 12, a cage 13 and a set of six pins 14. The housing comprises a cylindrical collar 1 6 and at one end an inwardly extending flange 17 and an outwardly extending flange 1 8. Six fixed equally spaced studs 19 extend through the collar 1 6 (only one being shown in Figure 2).

The spigot 12 is rotatably mounted in the housing 11 and is integrally formed with the cage 1 3 which is entirely located within the housing 11. At the outer end of the cage 13 there is a hexagonal head 1 5 which is adapted to fit in a corresponding recess 22 in a key 21.

The cage 13 defines six axial slots 23 in each of which one pin 14 is slidably located. Each pin 14 is urged outwards by a spring 24 but is prevented from leaving its slot 23 by the inner flange 1 7. The studs 19 extend through a circumferential slot 25 in the cage 1 3 and into the spaces between the pins 14.

Each pin 14 has a circumferential detent 26 formed at a particular distance d from the upper end of the pin 14. The axial extend of the detent 26 is somewhat greater than the thickness of the stud 1 9. The distance d will vary from pin to pin, from lock to lock.

In the locked position shown in the left hand portion of Figure 1, the spigot 12 is prevented from turning relative to the housing 11 by the studs 1 9 which come into contact with the pins 14. To unlock the lock the key 21 is used, the key 21 having six indentations 27 of varying depths, each one corresponding to the distance d associated with a particular pin 14. When this key 21 is applied to the lock with the head 1 5 located in the recess 22, the pins 14 are each depressed by the correct distance so that the detents 26 register with the studs 1 9. The pins 14 are then free to rotate past the studs 1 9 and so the cage 13, and thus the spigot 12, can be rotated using the key 21.The correct orientation of the key 21 with respect to the pins is achieved by means of a tab 28 on the key which passes through an aperture (not shown) in the inner flange 1 7.

It will be appreciated that whereas very precise machining and finishing is necessary to enable the rear pins in a conventional radial pin tumbler lock to re-enter the front cage when the lock is locked, such critical accuracy is not necessary in the construction described above. Similarlly, in the conventional construction and differing lengths of the pins must be formed with great precision whereas in the embodiment described above, the positioning of the detents 26 and dimensions of pins are not nearly as critical.

It will also be seen that in the above embodiment, a major proportion of the spindle 12 is substantial in diameter making the lock inherently less weak. Finally, sealing of the lock may be achieved simply by locating a seal between the spindle 12 and the housing 11 in the region 29.

It has been found by the Applicants that such a lock is capable of a great number of changes.

Claims

1. A security lock comprising a housing, a spigot, a cage and a plurality of pins, in which the pins are slidably located in the cage, the cage is rotationally fixed with respect to the spindle, and has means for engaging a key, the spindle is rotatably located within the housing, the housing has means for engaging the pins thereby preventing the pins, cage and spigot rotating relative to the housing, and in which the pins are each slidable through a predetermined distance to a position in which they do not engage the engagement means, whereby, when the correct key is fitted to the lock, the pins are each moved through their respective predetermined distances, and the pins, cage and spigot may be rotated relative to the housing.

2. A lock as claimed in Claim 1 in which the cage and spigot are integrally formed.

3. A lock as claimed in Claim 1 or Claim 2 in which the means engaging the pins comprise a plurality of studs extending radially inwards further than the radially outward extent of the pins, and each pin has a detent at a position which corresponds to the predetermined distance through which the pin is arranged to slide, the detent being such as to allow the pin to rotate past the stud.

4. A lock as claimed in any of Claims 1 to 3 in which each pin is slidable against the force of a spring.

5. A lock as claimed in any preceding claim in which the means for engaging the key is a hexagonal head arranged to mate with a corresponding recess in the key.

6. A lock as claimed in any preceding claim including a slot in the front of the housing arranged to receive tab on the key to ensure that the key is fitted in the correct orientation with respect to the pins.

7. A security lock constructed and arranged substantially as herein specifically described with reference to and as shown in the accompanying drawings.