GB2281057A

GB2281057A - Trailer security system

Info

Publication number: GB2281057A
Application number: GB9308769A
Authority: GB
Inventors: Norman John Hemmingsley
Original assignee: WOLVERHAMPTON ENTERPRISE LIMIT
Current assignee: WOLVERHAMPTON ENTERPRISE LIMIT
Priority date: 1993-04-28
Filing date: 1993-04-28
Publication date: 1995-02-22
Also published as: GB9308769D0

Abstract

An anti-theft device for a trailer (13) having a king pin (12) includes a jaw (18) movable between open and closed positions. In its closed position, the jaw (18) engages with the reduced diameter portion of the king pin (12) and is held in its closed position by a catch (27) which interengages with a pawl (28). Movement of the pawl (28) into its release position is effected on movement of a detent (31) coupled to a locking mechanism (21). <IMAGE>

Description

TRAILER SECURITY SYSTEMS Field of the Invention This invention relates to trailer security systems and is concerned with that type of trailer, normally referred to as a semi-trailer, which includes a king pin which is coupled to a skid plate on the tractor. The king pin includes a reduced diameter portion which cooperates with locating means on the skid plate, said reduced diameter portion defining, in effect, a channel around the king pin.

During the transport of goods, there are times when a trailer is left unattended. Unattended trailers can be a target for thieves, particularly if the contents of the trailer are valuable.

It is accordingly an object of the present invention to prevent a method of deterring the theft of trailers.

It is a further object of the present invention to provide a trailer anti-theft device.

Summary of the Invention According to a first aspect of the present invention there is provided a theft deterrent method applicable to a trailer having a king pin, said method comprising the fitting of a clamp around the king pin in such manner that the clamp is freely rotatable around the reduced diameter portion of the king pin and is held against axial separation from the king pin by its engagement within the channel defined by said reduced diameter portion without any requirement for external locking means.

The clamp preferably includes a jaw which is movable between an open position, in which the clamp can be fitted around the reduced diameter portion of the king pin, and a closed position in which the jaw is held by its engagement with a catch, with the arrangement such that displacement of the catch from the jaw to allow movement of the jaw into its open position can only be effected upon operation of a locking mechanism.

According to a second aspect of the present invention there is provided an anti-theft device for fitment to a king pin of a trailer, which king pin has a reduced diameter portion with which the device cooperates, the device comprising a main body and a jaw which is movable relative to the main body between an open position, for assembly around said reduced diameter portion, and a closed position in which the device is freely rotatable around the reduced diameter portion but is not axially separatable therefrom, the jaw and main body being held against separation from the king pin by engagement within the channel defined by the reduced diameter portion without any requirement for external locking means.

The jaw is preferably held in its closed position by its engagement with a catch and the arrangement is preferably such that displacement of the catch from the jaw to allow movement of the jaw into its open position can only be effected upon operation of a locking mechanism contained within the main body.

The jaw may be mounted for pivotal movement relative to the main body between its open and closed positions.

The catch is preferably spring-loaded towards a release position but, when the jaw is in its closed position, the catch is preferably held against movement towards its release position by engagement with a pawl which, in turn, is only movable upon operation of the locking mechanism contained within the main body.

Previous clamp devices for fitment to king pins have included jaws or the like which have fitted around the king pin and have been held in position by an external padlock. The hasp of the padlock has been accessible to determined thieves armed with cutters and the devices have thus not had the required deterrent effect.

The pawl is preferably acted on by a detent movable under the control of a key-operated or other locking mechanism. If a key-operated locking mechanism is employed, the locking mechanism may be operable by means of a generally cylindrical key or may include a cylinder or equivalent which is arranged for free-wheeling movement (without transmission of movement to the detent) except upon insertion of the correct key.

At the limit of its movement into its closed position, the jaw preferably comes into contact with a buffer. The buffer preferably also acts on the catch and the pawl to bias them into engagement with one another, movement of the detent under the action of the locking mechanism preferably serves to effect movement of the pawl against the biassing action of the buffer to move the pawl out of engagement with the catch to permit pivotal movement of the catch and thus allow movement of the jaw, under the biassing action of the buffer, towards its open position.

Brief Description of the Drawings Figure 1 is a side view of a tractor and trailer, Figure 2 is a detail view of a king pin on the trailer, Figure 3 is a sectional view of an anti-theft device for fitment to the king pin, the section of Figure 3 being at right angles too the axis of the king pin, Figure 4 is a sectional view of the anti-theft device along the line 4 - 4 of Figure 3, and Figure 5 is a further sectional view of the device as indicated by the arrows 5 - 5 in Figure 3.

Description of the Preferred Embodiment As shown in Figure 1, a tractor 10 has a skid plate 11 which is arranged for coupling engagement with a king pin 12 on a trailer 13. As can be seen from Figure 2, the king pin 12, which extends downwardly beneath the trailer 13, includes a cylindrical stem which, at a position spaced from its free end, includes a reduced diameter portion 14 which, in effect, provides a channel 15. The skid plate 11 on the trailer 10 includes locating formations (not shown) which engage within this channel 15.

The anti-theft device shown in Figures 3 to 5 is designed to fit around the king pin 12 so as to be freely rotatable about the axis of the king pin 12. The anti-theft device includes parts which are located within the channel 15 so that removal of the device from the king pin 12 is prevented, as explained in detail below. Thus, when the device is fitted in position around the king pin 12, it is not possible to engage the skid plate 11 with the king pin 12 and coupling of the tractor 10 to the trailer 13 is prevented.

The device includes top and bottom steel castings 16 and 17 between which a steel clamp jaw 18 is mounted. The jaw 18 is pivotally mounted between the castings 16 and 17 and is arranged for movement between a closed position, as shown, and an open position, as indicated in part as 18A. The top and bottom castings 16 and 17 are so shaped that, when the jaw 18 is in its open position, at 18A, the castings 16 and 17 can be fitted over the king pin 12 and the jaw 18 then pivoted into its closed position, in which portions of the jaw 18 enter the channel 15, as shown.

The part of the space between the castings 16 and 17 not covered by the jaw 18 is enclosed by a stack of steel laminations 19 fixed in position by steel dowels 20 extending between the top and bottom castings 16 and 17. As shown in the drawings, the laminations 19 provide a location and mounting for a locking mechanism 21 the design of which is such that a first collar 22 on a cylinder of the mechanism 21 seats in a recess afforded by the laminations 19 and a second collar 23 abuts a shoulder defined by the laminations 19. Positive fixing of the mechanism 21 is thus achieved. The top and bottom castings 16 and 17 and the laminations 19 together constitute a main body of the device, the locking mechanism 21 being contained within this main body.

The jaw 18 includes a nose portion 24 which enters within a mouth defined by the laminations 19 such that, when the jaw 18 is in its fully closed position, the nose portion 24 has engaged a rubber buffer 25, which acts as an anti-rattle stop and cushioning device. The nose portion 24 includes a transverse pin 26 which is arranged for engagement with a Ushaped catch 27 pivotally mounted between the top and bottom castings 16 and 17.

A pawl 28 is also pivotally mounted between the top and bottom castings 16 and 17. It includes a first limb 29 which is acted on by the rubber buffer 25 so as to be urged into the position shown in Figure 3 in which an end portion of a second limb 30 of the pawl 28 hooks over the end of one of the arms of the U-shaped catch 27 to hold the catch 27 in the position shown in Figure 3 (in engagement with the transverse pin 26) and thereby prevent movement of the jaw 18 out of its closed position. It is to be noted that the buffer 25 also acts on the catch 27 to bias it into the position shown in Figure 3.

The locking mechanism 21 includes a detent 31 which rotates with the cylinder of the mechanism 21 when the correct key is inserted. The key includes a generally cylindrical stem in which rebates are formed. The key-receiving slot of the mechanism 21 is of corresponding configuration such that the insertion of an incorrect key or other device cannot be used to apply a large torque to the cylinder to effect unauthorised rotation of the detent 31. The detent 31 bears against the end of the first limb 29 of the pawl 28.

Thus, when a correct key is inserted in the mechanism 21 and is rotated, such movement is transmitted to the detent 31 which causes pivotal movement of the pawl 28 against the action of the buffer 25. Such movement of the pawl 28 moves the end of the second limb 30 of the pawl 28 into a position in which it is no longer hooked over the arm of the catch 27. The catch 27 is thus free to pivot to allow the nose portion 24 of the jaw 18 to be displaced by the biassing action of the buffer 25 so that the jaw 18 is rotated in an anti-clockwise direction as viewed in Figure 3. The jaw 18 can thus be opened and the device as a whole removed from the king pin 12 to permit connection of a skid plate 11 to the king pin 12.

In an alternative arrangement, the locking mechanism 21 is such that, except when a correct key is inserted, the cylinder will merely free-wheel without the transmission of torque to the detent 31.

Although reference has been made above to the use of a key-operated locking mechanism, other security systems could be employed. For example, a multi-digit code may have to be entered on a keyboard or the like to perform an unlocking action.

An important advantage of the invention is that it provides an anti-theft device which can readily be fitted to the king pin of a trailer without the person fitting the device to the king pin requiring a key or the like. Thus, when the jaw 18 is moved into its closed position around the king pin 12, it will be held in that position by the action of the catch 27 and pawl 28 without any key or equivalent operation. The device is of such size that it can readily be carried in the cab of a tractor.

A further important advantage of the invention is that the interengaging parts and the locking mechanism are contained wholly within the device, in contrast with previous proposals which have included the use of external padlocks. A significant improvement in the level of security afforded by the device is thus obtained.

Claims

Claims:

1. A theft deterrent method applicable to a trailer having a king pin, said method comprising the fitting of a clamp around the king pin in such manner that the clamp is freely rotatable around the reduced diameter portion of the king pin and is held against axial separation from the king pin by its engagement within the channel defined by said reduced diameter portion without any requrement for external locking means.

2. A method as claimed in Claim 1, in which the clamp includes a jaw which is movable between an open position, in which the clamp can be fitted around the reduced diameter portion of the king pin, and a closed position in which the jaw is held by its engagement with a catch, with the arrangement such that displacement of the catch from the jaw to allow movement of the jaw into its open position can only be effected upon operation of a locking mechanism.

3. A method as claimed in Claim 1, which includes the use of a device substantially as hereinbefore described with reference to and as shown in Figures 3 to 5 of the accompanying drawings.

4. An anti-theft device for fitment to a king pin of a trailer, which king pin has a reduced diameter portion with which the device cooperates, the device comprising a main body and a jaw which is movable relative to the main body between an open position, for assembly around said reduced diameter portion, and a closed position in which the device is freely rotatable around the reduced diameter portion but is not axially separatable therefrom, the jaw and main body being held against separation from the king pin by engagement within the channel defined by the reduced diameter portion without any requirement for external locking means.

5. An anti-theft device as claimed in Claim 4, in which the jaw is held in its closed position by its engagement with a catch.

6. An anti-theft device as claimed in Claim 5, in which the arrangement is such that displacement of the catch from the jaw to allow movement of the jaw into its open position can only be effected upon operation of a locking mechanism contained within the main body.

7. An anti-theft device as claimed in any one of Claims 4 to 6, in which the jaw is mounted for pivotal movement relative to the main body between its open and closed positions.

8. An anti-theft device as claimed in Claim 5, in which the catch is spring-loaded towards a release position.

9. An anti-theft device as claimed in Claim 8 in which, when the jaw is in its closed position, the catch is held against movement towards its release position by engagement with a pawl.

10. An anti-theft device as claimed in Claim 9, in which the pawl is acted on by a detent movable under the control of the locking mechanism.

11. An anti-theft device as claimed in Claim 10, in which the locking mechanism includes a cylinder or equivalent which is arranged to receive a generally cylindrical key.

12. An anti-theft device as claimed in any one of Claims 9 to 11, in which, at the limit of its movement into its closed position, the jaw comes into contact with a buffer.

13. An anti-theft device as claimed in Claim 12, in which the jaw also acts on the catch and the pawl to bias them into engagement with one another.

14. An anti-theft device for fitment to a king pin of a trailer, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.