GB1595063A - Motor vehicle anti-theft devices - Google Patents

Description

(54) IMPROVEMENTS RELATING TO MOTOR VEHICLE ANTI-THEFT DEVICES (71) We, L & F WILLENHALL LI MITED, a British Company of Church Street, Willenhall, West Midlands do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to anti-theft devices for motor vehicles.

The most common form of anti-theft device fitted to vehicles manufactured at the present time is a device for locking a rotatable steering shaft of the vehicle. Such devices are mounted on a non-rotatable steering column within which the steering shaft is disposed. The known devices comprise a bolt which can project through an opening in the steering column into a slot formed in the rotatable shaft itself or, more commonly, in a bush which is welded to the shaft. When the bolt is engaged in the slot, rotation of the steering shaft is prevented.

The bolt can be withdrawn from the slot by means of a key-operated lock mechanism, thereby freeing the steering shaft.

One disadvantage of the known steering shaft locking devices referred to is that rotation of the shaft is prevented by engagement of the shaft or bush with a face portion of the bolt which is situated close to the axis of rotation of the shaft. Any torque which is transmitted by the steering shaft to the bolt therefore establishes a relatively high contact pressure between the shaft and/or its bush and bolt.

Movement of the bolt out of the slot can be opposed by a correspondingly high frictional force so that a user will experience difficulty in operating the lock mechanism to withdraw the bolt from the slot whenever there is applied to the steering shaft a torque which is resisted by the bolt.

According to a first apsect of the present invention, there is provided a motor vehicle having a steering shaft which is rotatable about an axis, a non-rotatable housing through which the steering shaft extends and an anti-theft device which comprises a lockable element constrained to rotate with the steering shaft, extending radially outwardly from the shaft and extending around the shaft, a locking member mounted on the housing, a plurality of formations in said lockable element, said formations being spaced from one another around the shaft, being spaced radially from the shaft and each being adapted to receive the locking member, the locking member being mounted for movement relative to the housing between a locking position in which it engages in one of the formations of the lockable element and a releasing position in which it does not so engage, an abutment which is constrained against rotation with the shaft and is engageable with the lockable element to prevent unauthorised removal of the lockable element in the axial direction from the shaft and a key-operated lock mechanism for controlling movement of the locking member.

In this arrangement, the formations in which the locking member engages are spaced radially outwardly from the steering shaft. Accordingly, the contact pressure between the lockable element and the locking member which exists when a given torque is resisted by the locking member is smaller than the contact pressure which exists under similar conditions between the bolt and the steering shaft and/or its bush in the known steering shaft locking device herein before referred to. Under the conditions where a torque which is applied to the steering shaft is resisted by the anti-theft device, operation of the device to free the steering shaft for rotation is easier than is the case with the known device.

Preferably, the locking member is adapted to engage the lockable element in such a manner as to prevent unauthorised removal of the lockable element in the axial direction from the shaft when the locking member is in its locking position. In this case, the abutment may be arranged to be engageable with the lockable element to prevent unauthorised removal thereof only when the locking member is unable to assume its locking position.

The locking member is preferably arranged to move towards the axis of the steering shaft when the locking member moves from is releasing position to its locking position. With this arrangement, unauthorised movement of the locking member from its locking position to its releasing position other than by proper operation of the lock mechanism is relatively difficult, as the locking member must be moved away from the axis. It is generally easier to drive a member towards the axis than to draw the member away from the axis.

According to a second aspect of the invention, there is provided an anti-theft device for a motor vehicle having a rotatable steering shaft which extends through a non-rotatable housing, the device comprising a body which in use is rigidly secured to a non-rotatable housing of a steering shaft of the vehicle, a lockable element which is adapted to be secured to the steering shaft for rotation therewith, a locking member mounted in the body for movement relative thereto between locking and releasing positions, an abutment on the body which is engageable, when the device is in use, with the lockable element to prevent unauthorised removal of the lockable element in the axial direction from the shaft and a keyoperated lock mechanism for controlling movement of the locking member relative to the body, wherein the lockable element has a plurality of formations, in any selected one of which the locking member can be engaged when the device is in use and the locking member is in its locking position, said formations are spaced from one another around an axis of the lockable element, and the locking member can be withdrawn from the formation by moving the locking member to its releasing position.

The invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows partly in cross section certain parts of an anti-theft device in accordance with the invention Figure 2 is a view on the arrow II of Figure 1 showing the device and certain adjacent parts of a vehicle to which the device is fitted, Figure 3 is a view of the device on the arrow III of Figure 2, Figure 4 shows in cross section on the line IV-IV of Figure 1 the device and certain adjacent parts of the vehicle, a locking member of the device being shown in a locking position, Figure 5 is a fragmentary view similar to Figure 4 showing the locking member in a releasing position.

Figure 6 is a view on the arrow VI of Figure 1 with certain parts broken away and the locking member in the releasing position.

Figure 7 is a view similar to Figure 4 illustrating a modified device, and Figure 8 is a view similar to Figure 6, also of the modified device shown in Figure 7.

The device illustrated in Figures 1 to 6 of the accompanying drawings is intended for locking the rotatable shaft of a vehicle steering column against rotation. The device includes a lockable element in the form of a dished plate 10 which, when the device is fitted on a vehicle, is secured to the steering shaft 12 and is constrained to rotate therewith. As shown in Figure 4, the plate is welded to a steering wheel boss 11 which is fitted onto a splined end portion of the steering shaft 12 and is retained thereon by a nut 13. The boss 11 has internal splines which co-operate with those of the shaft to prevent rotation of the boss relative to the shaft when the steering wheel is secured to the shaft. The steering wheel can be adjusted relative to the shaft angularly about an axis 14 of the shaft by removing the nut 13, withdrawing the boss 11 from the shaft and fitting the boss to the shaft once more in a selected position. The steering wheel, which is not fully illustrated in the drawings, comprises spokes and a rim of moulded plastics material, each spoke having a wire core and an end portion 15 of each core being welded to the boss 11 and plate 10 where these are welded together.

The vehicle to which the device is fitted further comprises a tubular housing 16 through which the rotatable steering shaft 12 extends. The housing is non-rotatable, being secured to a body of the vehicle. A body 17 of the anti-theft device is secured to the housing 16 so that this body also is constrained against rotation. The body 17 is fitted to the housing 16 before the lockable element and steering wheel are fitted to the shaft 12, the housing being received in a circular aperture of the body. The body 17 is then secured against rotation and axial displacement relative to the housing by a pin 18 which is inserted into a bore formed in the body and the mid portion of which engages in an aperture in the housing as shown in Figure 4. To provide further security against rotation of the body 17 relative to the housing 16, the end of the latter is of castellated form and is received in a complementary socket portion 19 of the body.

The plate 10 is symmetrical about the axis 14 and has a diameter between three and four times the diameter of the shaft 12. A peripheral flange 20 of the plate is perpendi-.

cular to the axis and lies radially outwardly of the housing 16 and socket portion 19 of the body. In the flange, there is formed a plurality of formations 21 for receiving a locking member of the device. As shown in Figure 3, each formation 21 is in the form of a rectangular opening which extends radially inwardly from the periphery of the plate 10 approximately to the radially inner boundary of the flange 20. The formations 21 are spaced apart around the axis 14 by a distance which is typically somewhat greater than the width of each formation and there are typically eight formations in the flange 20.

Those parts of the body 17 which have already been referred to are preferably integral with one another and constitute parts of a main body member 22. The body 17 includes a further, axially projecting part 23 which lies radially outwardly of the flange 20 and projects past the flange towards the steering wheel. On the part 23, there is an abutment 24 which projects towards the axis 14 at a position between the flange 20 and the steering wheel boss 11. The abutment overlaps the flange 20 and has a size and shape such that it can just pass through any one of the openings 21. Accordingly, once the body 17 has been secured to the housing 16, the steering wheel and lockable plate 10 can be fitted on to and removed from the steering shaft 12 only when one of the formations 21 is aligned with the abutment 24. When there is no such alignment, the abutment prevents removal of the steering wheel and plate 10number 10.

The main body member 22 defines a cavity in which the locking member 25 and a key-operated lock mechanism 26 for controlling movement of the locking member are disposed. The main body member further defines a circular opening 46 through which the lock mechanism is accessible for insertion of a key, a larger opening 27 which faces away from the axis 14 and a smaller opening 28 which faces towards the axis. All of these openings communicate with the internal chamber of the main body member.

At the end of the main body member remote from the opening 46, there is formed a recess 29 for receiving an electrical switch which is also required to be controlled by the lock mechanism.

The body 17 further comprises a closure member 30 integral with the part 23 and having an outer wall portion which closes the larger opening 27 when the device is assembled. The closure member further comprises a portion 31 which extends from the outer wall portion across the cavity of the main body member into the smaller opening 28 and a portion 32 which projects from the outer wall portion across the cavity of the main body member at a position near to the opening 46 thereof.

The locking member 25 is guided by the portion 31 of the closure member for movement towards and away from the axis 14 between a releasing position shown in Figure 4 and a locking position shown in Figure 5. The locking member is urged towards its locking position by a spring 33 which acts between the locking member and the closure member 30.

The locking member 25 comprises three limbs 34, 35 and 36, each of which has a T-shaped cross section. As shown, the locking member is formed of two metal pressings, one of which is the mirror image of the other. The pressings are secured back to back by welding or in any other convenient manner so that the pressings collectively form the stem of each T-shaped limb.

Each pressing forms a respective half of the cross bar of each T-shaped limb. The limb 34 slides in the portion 31 of the closure member and the cross bar of this limb is engaged by the spring 33. The limb 35 is engaged in a head 37 which is also mounted in the closure member 30 for sliding movement with the locking member. The cross bar of the limb 35 constrains the head and locking member to move together towards and away from the axis 14.

The limb 36 extends away from the limbs 34 and 35 in a direction parallel to the axis 14 towards the steering wheel. The cross bar of the limb 36 is situated inside the part 23 of the closure member and at a position along the axis which is nearer to the boss 11 then is the flange 20. When the locking member is in its locking position, the stem of the limb 36 is engaged in one of the formations 21 and thereby constrains the plate 10 against rotation. Since the cross bar of the limb 36 then overlies the flange 20, it prevents unauthorised removal of the plate in the axial direction from the shaft 12. When the locking member is in its releasing position, the limb 36 is spaced radially outwardly from the flange 20 so that the locking member restrains the plate 10 against neither rotation nor axial movement of the shaft 12.

The lock mechanism 26 includes a barrel 38 having a slot 39 in which a key can be received. A cylindrical outer end portion of the barrel is received with a slight clearance in the opening 46 of the main body member so that an outer end face of the barrel, in which there is an open end of the key slot. is accessible from the outside of the body when the device is in use. The barrel contains tumblers whereof, when the key is absent, end portions project radially from the barrel. That part of the barrel which contains the tumblers is rotatably received in the portion 32 of the closure member, this portion having a pair of diametrically opposite channels to receive the end portions of the tumblers. A spindle 40 extends from the barrel 38 through an aperture in the head 37 into a driving member 41 adapted to drive a switch fitted in the recess 29. On the spindle 40, there is mounted a cam 42 which is engageable with the head 37 to displace the latter in a direction away from the axis 14 when the barrel is rotated. A retaining element 43 is mounted in the closure member 30 for co-operation with a plunger 44 mounted in the head 37 to retain the head and locking member 25 in the releasing position until the key is withdrawn from the barrel 38. The retaining element, plunger and the lock mechanism generally are arranged as described in the Complete Specification of our co-pending application No. 50918/76, serial no. 1595062 to which reference should be made for further details.

During assembly of the device, the closure member 30, locking member 25, spring 33, head 37, lock mechanism 26, spindle 40, driving member 41, cam 42, retaining element 43 and plunger 44 are assembled together to form an assembly which is then inserted into the cavity of the main body member 22 through the opening 27. The body of the device is then fitted to the housing 16 and secured thereto. The portion 31 of the closure member engages in a slot formed at one side of the housing 16, thereby providing further contraint against rotation of the body 17 relative to the housing. With the locking member 25 held in its releasing position (because the key is present in the slot 39), the steering wheel and plate 10 are fitted to the shaft 12, the abutment 24 passing through one of the formations 21.

When the vehicle is to be driven after the key has been removed from the barrel 38, the key must first be inserted into the barrel once more to withdraw the tumblers from the channels in the closure member 30. The barrel is then rotated to move the locking member to its releasing position and to operate a switch fitted in the recess 29.

When it is subsequently desired to immobilise the vehicle, the barrel is rotated to its initial position and the key is withdrawn.

This releases the locking member 25 for movement towards the axis 14. If the stem of the limb 36 of the locking member is aligned with one of the formations 21, the locking member will move immediately into its locking position. If the limb 36 is not so aligned with one of the formations 21, the stem of this limb will move into engagement with a part of the flange 20 which lies between adjacent formations 21. In this position, the locking member does not prevent withdrawal of the plate 10 from the shaft 12 in the axial direction. Thus, it would be possible for a thief to remove the nut 13 and then withdraw the steering wheel and plate 10 from the shaft 12 to gain access to the anti-theft device, unless the steering wheel is otherwise restrained.

The device could be rendered inoperative and the steering wheel then replaced so that the vehicle could be driven. This possibility is avoided by the presence of the abutment 24 which, whenever the stem of the limb 36 is out of alignment with a formation 21, overlies a part of the flange 20 and itself prevents unauthorised withdrawal of the plate 10 from the shaft.

It will be noted that movement of the locking member 25 from its locking position to its releasing position is in a direction away from the axis 13. Furthermore the locking member is enclosed by the body 17 and access can be gained to the locking member only by removing a part of the body. If an unauthorised person wishing to unlock the shaft 12 gained access to the locking member by, for example, drilling an aperture in the body 17, such access would be gained most easily to that side of the locking member which faces away from the axis.

This would not enable the unauthorised person to move the locking member from the locking position to the releasing position.

The lockable plate 10 and the locking member 25 may conveniently be formed of steel. The main body member 22 and the closure member 30 are conveniently formed by diecasting a zinc-based alloy. In view of the fact that such alloys are weaker than steel, the part 23 of the body may be reinforced by steel or formed entirely of steel.

Figures 7 and 8 of the accompanying drawings illustrate a modification of the device shown in Figures 1 to 6. Certain parts of the modified device correspond to parts hereinbefore described with reference to Figures 1 to 6 and such corresponding parts are indicated by like reference nurnerals with the prefix 1. Except for the differences hereinafter mentioned, the preceding description is deemed to apply to such corresponding parts.

One important difference between the modified device of Figures 7 and 8 and of the device of Figures 1 to 6 is that the number of openings 121 in the lockable plate 110 of the modified device is considerably greater than the number of openings 21 in the plate 10. In the particular example of device illustrated in Figures 7 and 8, there are twenty four openings 121 in the flange 120. Adjacent openings are separated by parts of the flange having approximately the same size as each of the openings and the centres of adjacent openings are spaced apart angularly about the axis 114 by an angle of 15".

Another important difference is that the locking member 125, when in its locking position, engages simultaneously in more than one of the openings 121. The limb 136 of the locking member has a cross section as viewed towards the axis 114, with the shape of a double-U, as shown in Figure 8. The two U shapes are spaced apart by a gap which is sufficiently wide to receive one of the portions 150 of the flange 120 between adjacent openings 121. The gap also receives a web 151 which is integral with the axially projecting part 123 of the body, this web providing guidance for the locking member when the latter moves between its locking and releasing positions. Further flange portions 150 are received one within each U of the limb 136 so that, when the locking member is in its locking position, four distinct parts of this limb are engaged in respective openings 121 to constrain the plate 110 against rotation.

When the locking member 125 is in its locking position, the base of each U of the limb 136 overlies a respective one of the flange portions 150. Accordingly, the locking member prevents unauthorised removal of the plate 110 in the axial direction from the shaft 112.

The locking member 125 is formed of two metal pressings, one of which is the mirror image of the other. The pressings are secured back to back by welding or in any other convenient manner. The pressings collectively constitute the limb 134 which, as shown in Figure 7, is L-shaped and has a flat cross section. The limb 135 also has a flat cross section and is L-shaped as viewed in Figure 7, this limb being engaged in the head 137 to ensure that the locking member and head move together in a direction towards and away from the axis 114.

On the axially projecting part 123 of the body, there are two abutments 124 which project towards the axis 114 at a position between the flange 120 and the steering wheel boss 111. These abutments overlap the flange 120, each having a size and shape such that they can just pass through respective ones of the openings 121 and are spaced apart by the same distance as adjacent openings 121. As shown in Figure 8, each of the abutments 124 is aligned with one leg of a respective one of the U-shapes of the limb 136 of the locking member. Accordingly, when the legs of the U-shapes are aligned with respective portions 150 of the flange, thereby preventing movement of the locking member to its locking position, the abutments 124 are also aligned with respective flange portions 150 and so prevent unauthorised withdrawal of the plate 110 and steering wheel from the shaft 112.

When a vehicle to which the device is fitted is stationary, and the steering wheel is turned, the treads of the tyres of the steerable wheels do not move relative to the ground on which the vehicle is standing to the same degree as the steering wheel is turned. Because there is considerable friction between the tyre treads and the ground, the steering mechanism and tyres are subjected to stress if the steering wheel is turned whilst the vehicle is stationary. The tyres and various components of the steering mechanism undergo elastic deformation so that the movement of the tyre treads relative to the ground lags behind the movement of the steering wheel. If, after the steering wheel has been turned, it is locked against further movement, there will be in the steering mechanism and tyres a residual stress which results in a torque being applied to the steering shaft. This torque is resisted by the locking device so that pressure contact is established between the locking device and a part associated with the shaft. This pressure contact gives rise to friction which opposes operation of the device to unlock the steering shaft. If the steering wheel is turned sufficiently to cause movement of the tyre treads relative to the ground, the residual stress in the steering mechanism and tyre will have a maximum value corresponding to the friction between the tyres and the ground.

The modified device shown in Figures 7 and 8 avoids the establishment of this maximum stress in the steering mechanism and tyres by ensuring that, when the key is absent, the steering wheel cannot be turned sufficiently to cause movement of the tyre treads relative to the ground. The maximum angle through which the steering wheel can be turned when the key is absent is the angle between the centre lines of adjacent openings 121. This angle is 15". When the vehicle is stationary, a rotation of the steering wheel through 15 is not sufficient to cause movement of the tyre treads relative to the ground and is therefore not sufficient to establish the maximum residual stress in the steering mechanism and tyres. Accordingly, the torque arising from the residual stress is invariably fairly low and it is correspondingly easy to operate the anit-theft device to move the locking member to its releasing position.

WHAT WE CLAIM IS: 1. A motor vehicle having a steering shaft which is rotatable about an axis, a non-rotatable housing through which the steering shaft extends and an anti-theft device which comprises a lockable element

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. 120. Adjacent openings are separated by parts of the flange having approximately the same size as each of the openings and the centres of adjacent openings are spaced apart angularly about the axis 114 by an angle of 15". Another important difference is that the locking member 125, when in its locking position, engages simultaneously in more than one of the openings 121. The limb 136 of the locking member has a cross section as viewed towards the axis 114, with the shape of a double-U, as shown in Figure 8. The two U shapes are spaced apart by a gap which is sufficiently wide to receive one of the portions 150 of the flange 120 between adjacent openings 121. The gap also receives a web 151 which is integral with the axially projecting part 123 of the body, this web providing guidance for the locking member when the latter moves between its locking and releasing positions. Further flange portions 150 are received one within each U of the limb 136 so that, when the locking member is in its locking position, four distinct parts of this limb are engaged in respective openings 121 to constrain the plate 110 against rotation. When the locking member 125 is in its locking position, the base of each U of the limb 136 overlies a respective one of the flange portions 150. Accordingly, the locking member prevents unauthorised removal of the plate 110 in the axial direction from the shaft 112. The locking member 125 is formed of two metal pressings, one of which is the mirror image of the other. The pressings are secured back to back by welding or in any other convenient manner. The pressings collectively constitute the limb 134 which, as shown in Figure 7, is L-shaped and has a flat cross section. The limb 135 also has a flat cross section and is L-shaped as viewed in Figure 7, this limb being engaged in the head 137 to ensure that the locking member and head move together in a direction towards and away from the axis 114. On the axially projecting part 123 of the body, there are two abutments 124 which project towards the axis 114 at a position between the flange 120 and the steering wheel boss 111. These abutments overlap the flange 120, each having a size and shape such that they can just pass through respective ones of the openings 121 and are spaced apart by the same distance as adjacent openings 121. As shown in Figure 8, each of the abutments 124 is aligned with one leg of a respective one of the U-shapes of the limb 136 of the locking member. Accordingly, when the legs of the U-shapes are aligned with respective portions 150 of the flange, thereby preventing movement of the locking member to its locking position, the abutments 124 are also aligned with respective flange portions 150 and so prevent unauthorised withdrawal of the plate 110 and steering wheel from the shaft 112. When a vehicle to which the device is fitted is stationary, and the steering wheel is turned, the treads of the tyres of the steerable wheels do not move relative to the ground on which the vehicle is standing to the same degree as the steering wheel is turned. Because there is considerable friction between the tyre treads and the ground, the steering mechanism and tyres are subjected to stress if the steering wheel is turned whilst the vehicle is stationary. The tyres and various components of the steering mechanism undergo elastic deformation so that the movement of the tyre treads relative to the ground lags behind the movement of the steering wheel. If, after the steering wheel has been turned, it is locked against further movement, there will be in the steering mechanism and tyres a residual stress which results in a torque being applied to the steering shaft. This torque is resisted by the locking device so that pressure contact is established between the locking device and a part associated with the shaft. This pressure contact gives rise to friction which opposes operation of the device to unlock the steering shaft. If the steering wheel is turned sufficiently to cause movement of the tyre treads relative to the ground, the residual stress in the steering mechanism and tyre will have a maximum value corresponding to the friction between the tyres and the ground. The modified device shown in Figures 7 and 8 avoids the establishment of this maximum stress in the steering mechanism and tyres by ensuring that, when the key is absent, the steering wheel cannot be turned sufficiently to cause movement of the tyre treads relative to the ground. The maximum angle through which the steering wheel can be turned when the key is absent is the angle between the centre lines of adjacent openings 121. This angle is 15". When the vehicle is stationary, a rotation of the steering wheel through 15 is not sufficient to cause movement of the tyre treads relative to the ground and is therefore not sufficient to establish the maximum residual stress in the steering mechanism and tyres. Accordingly, the torque arising from the residual stress is invariably fairly low and it is correspondingly easy to operate the anit-theft device to move the locking member to its releasing position. WHAT WE CLAIM IS:

1. A motor vehicle having a steering shaft which is rotatable about an axis, a non-rotatable housing through which the steering shaft extends and an anti-theft device which comprises a lockable element

constrained to rotate with the steering shaft, extending radially outwardly from the shaft and extending around the shaft, a locking member mounted on the housing, a plurality of formations in said lockable element, said formations being spaced from one another around the shaft, being spaced radially from the shaft and each being adapted to receive the locking member, the locking member being mounted for movement relative to the housing between a locking position in which it engages in one of the formations of the lockable element and a releasing position in which it does not so engage, an abutment which is constrained against rotation with the shaft and is engageable with the lockable element to prevent unauthorised removal of the lockable element in the axial direction from the shaft and a key-operated lock mechanism for controlling movement of the locking member.

2. A motor vehicle according to Claim 1 wherein the locking member is adapted to engage the lockable element in such a manner as to prevent unauthorised removal of the lockable element in the axial direction from the shaft when the locking member is in the locking position.

3. A vehicle according to Claim 2 wherein the abutment is arranged to be engageable with the lockable element to prevent unauthorised removal thereof only when the locking member is unable to assume its locking position.

4. A vehicle according to any preceding claim wherein the locking member is arranged to move towards the axis of the steering shaft when the locking member moves from its releasing position to its locking position.

5. A vehicle according to Claim 2 wherein the lockable element comprises a flange which projects radially from the shaft and in which said formations are formed and the locking member, when in its locking position, overlies an axially facing surface of the flange.

6. An anti-theft device for a vehicle having a rotatable steering shaft which extends through a non-rotatable housing, the device comprising a body which in use is rigidly secured to a non-rotatable housing of a steering shaft of the vehicle, a lockable element which is adapted to be secured to the steering shaft for rotation therewith, a locking member mounted in the body for movement relative thereto between locking and releasing positions, an abutment on the body which is engageable, when the device is in use, with the lockable element to prevent unauthorised removal of the lockable element in the axial direction from the shaft and a key-operated lock mechanism for controlling movement of the locking member relative to the body, wherein the lockable element has a plurality of formations, in any selected one of which the locking member can be engaged when the device is in use and the locking member is in its locking position, said formations are spaced from one another around an axis of the lockable element and the locking member can be withdrawn from the formation by moving the locking member to its releasing position.

7. A vehicle according to any one of Claims 1 to 5 or a device according to Claim 6 wherein the abutment is fixed with respect to the body.

8. A vehicle according to any one of Claims 1 to 5 or Claim 7 or a device according to any one of Claims 6 and 7 wherein, when the locking member is in its locking position, a plurality of portions of the locking member engage in respective ones of said formations.

9. A vehicle anti-theft device substantially as herein described with reference to and as shown in Figures 1 to 6 of the accompanying drawings.

10. A vehicle anti-theft device substantially as herein described with reference to and as shown in Figures 7 to 8 of the accompanying drawings.