GB2380230A

GB2380230A - Ram lock

Info

Publication number: GB2380230A
Application number: GB0207919A
Authority: GB
Inventors: Ian Michael Wright
Original assignee: Mawsley Machinery Ltd
Current assignee: Mawsley Machinery Ltd
Priority date: 2001-09-26
Filing date: 2002-04-05
Publication date: 2003-04-02
Anticipated expiration: 2022-04-05
Also published as: GB0207919D0; GB0123187D0; FR2830059A1; GB2380230B

Abstract

The ram lock comprises a pair of semi-cylindrical shells 2, 3 connected together along a common edge by hinge pin 10. Semi-cylindrical lock shells 15, 17 are secured to the opposite edges of the semi-cylindrical shells such that the free edges thereof 19, 20 abut each other when the ram lock is closed. Bushes 21,22,23 are located within and secured to the lock shells and bores 24, 28, 29 align when the ram lock is closed allowing locking pin 27 to be locked in position by a key operated lock 25 to prevent separation of the lock shells. The abutment of the lock shell edges means that even if the hinge pin is cut then the shells cannot be separated. End flange 11 strengthens the shells and protects the hinge pin from removal by drifting. Prevents retraction of e.g. a hydraulic steering ram as a security or safety device.

Description

R\M LOCK

This invention relates to a ram lock, that is to say a device for locking a hydraulic or pneumatic ram against specified movements which would otherwise be possible. The preferred embodiment of the invention provides a device which prevents or limits shortening of the ram by preventing or limiting movement of the piston or piston rod of the ram into the cylinder of the ram.

On occasions, it is desirable to lock a hydraulic or pneumatic ram in a manner which prevents or limits movement of the ram in the retraction direction. One application of this technique is to lock one or more steering rams of a hydraulically steered vehicle (for example a dumper truck or forklift truck) to prevent theft of the vehicle.

In principle, a hydraulic or pneumatic ram can be locked by placing a sleeve around the exposed piston or piston rod of the ram and locking the sleeve in position by means of a suitable key operated lock. The presence of the sleeve will prevent retraction of the piston or piston rod and will therefore prevent shortening of the ram In practice, however, if the purpose of the locking is as a security measure it is difficult to produce a lock which is immune to attack using relatively simple hand or power tools. If, for example, the lock is in the form of two semi-

cylindrical portions which are connected together by a hinge along one edge and are provided with locking means at the opposite edge, cutting of the hinge pin by means of a tool such as an angle grinder or even a hacksaw leads to relatively easy removal of the lock.

The present invention relates to a ram lock which is designed to resist attacks in the manner described above.

According to one aspect of the present invention there is provided a ram lock comprising two semi-cylindrical shells connected together along respective longitudinal edges thereof by means of a hinge, the opposite edges of each semi-cylindrical shell being provided with inter-

engaging components which can be locked together by means of a key operated lock and which are constructed such that, even if the hinge is destroyed, the shells cannot be separated to permit removal of the lock from its operative position.

The invention will be better understood from the following description of a preferred

embodiment thereof, given by way of example only, reference being had to the accompanying drawings wherein: Figure 1 is a schematic perspective view of a ram lock with the shells thereof locked together in their use configuration; and Figure 2 is a view of the lock of Figure 1 in its open configuration.

Turning firstly to Figure 1, the illustrated ram lock 1 comprises two shells 2, 3 which are of substantially semi-cylindrical form, and which are connected together at respective edges 4, 5 of the shells by a hinge 6 The hinge 6 comprises a plurality of cylindrical tubes 7, 8 and 9 which are each welded to one ofthe shells 2, 3 and through which a common hinge pin 10 (Figure 2) extends, thereby forming a conventional hinge. As illustrated, the cylindrical tubes 7 and 9 are secured to the shell 2 whilst the cylindrical tube 7 is secured to the shell 3. Those skilled in the art will appreciate that a larger number of discreet cylindrical tubes may be provided with alternate cylindrical tubes being secured to the shells 2 and 3 respectively.

At each end of each shell 2, 3 an outwardly extending flange 1 1 is secured The flanges 1 1 provide general strengthening at the ends of the shells. Also, as best illustrated in Figure 2, the shells protect the ends ofthe hinge pin 10, when the ram lock is in its close configuration, thereby preventing removal ofthe hinge pin 10 by drifting from one end.

It will be noted that the hinge 6 may relatively easily be defeated by means of cutting or grinding through the hinge pin at the points 12, 13 where the cylindrical tubes of the hinge meet If the hinge pin 10 is cut at this point by means of a hacksaw or angle grinder the hinge is no longer effective to maintain the edges 4, S adjacent each other and unless suitable means are provided to prevent separation of these edges the lock could readily be removed from its operative position once the required cuts have been made. In order to prevent removal of the lock as outlined above, the preferred embodiment of the present invention is provided with a locking assembly 14 which, provided that it remains intact, will prevent separation ofthe shells 2, 3 even if the hinge pin 10 is cut as outlined above.

The locking assembly 14 comprises a first semi-cylindrical lock shell 15 which is secured by welding to the edge 16 of the shell 2 which is remote from the hinge 6. A second semi-

cylindrical lock shell 17 is secured by welding to the edge 1 8 of the shell 3 which is remote from the hinge 6. The arrangement is such that when the ram lock is in the closed configuration illustrated in Figure 1, the free edge 19 ofthe lock shell 15 abuts the free edge 20 ofthe lock shell 17. A pair of substantial metal bushes 21, 22 are secured to the shell 15, preferably by welding.

The outside diameter of the bushes 21, 22 is such that they nest within the shell 15. Similarly, a substantial bush 23 is secured to the shell 17, preferably by welding, and is again of a diameter to nest within the bush 17. The various bushes are sized and positioned such that when the ram lock is in the closed configuration illustrated in Figure 1 the bush 23 is located snugly between the bushes 21 and 22, with the axial bores ofthe bushes all coaxial.

The bore 24 of the bush 21 is sized to receive a key operated lock 25 of conventional design. An appropriate profile is provided within the bore 24 to receive locking dogs 26 associated with the lock 25. A pin 27 is secured to the lock 25 and the bores 28, 29 of the bushes 22, 23 are sized snugly to receive the pin 27. The pin 27 may be formed of a hard or hardened material.

In use, the ram lock is offered up to a ram to be secured in its open configuration as illustrated in Figure 2, and the two halves ofthe lock are rotated about the hinge 6 to bring the bush 23 into position between the bushes 21 and 22, and to bring the edges 19, 20 ofthe shells 15, 19 into engagement with each other.

The pin 27 is then slid home and the lock 25 set to prevent removal ofthe pin. The components are then in the configuration illustrated in Figure 1. It will be noted that in this configuration the number of bushes present within the locking assembly 14 is not apparent from the exterior of the device. Further, the positions of the ends of the respective bushes are not visible from the exterior of the device. Hence, anyone seeking to attack the locking assembly 14 cannot tell where to cut in order to allow separation of the components. Further, the locking pin 27 is of a substantial profile and can be rendered difficult to cut, for example by being manufactured from a suitable hard material or being mounted to the lock in such a manner that the pin 27 can freely rotate.

If an attempt is made to attack the ram lock by cutting through the hinge pin 10 as described above, the ram lock cannot be removed because the engagement of the free edges 19, 20 of the shells 15, 17 prevent rotation ofthe shells 2, 3 about the pin 27.

The invention provides a simple and robust lock which provides a substantially higher degree of security there would be available if the locking assembly 14 were replaced by a simple locking arrangement - for example a pair of rings that can be secured together by a padlock.

Claims

CLAIMS:

1. A ram lock comprising two semi-cylindrical shells connected together along first respective longitudinal edges thereof, the opposite longitudinal edges of each semi-cylindrical shell being provided with inter-engaging components which can be locked together by means of a key operated lock and which are constructed such that, even if the means connecting the first respective longitudinal edges of the shells are destroyed the shells cannot be separated to permit removal of the lock Dom its operative position.

2. A ram lock according to Claim 1 wherein the means connecting the shells along their

first respective longitudinal edges comprises a hinge which permits the semi-cylindrical shells to be hinged apart so as to be positioned around and removed from a ram.

3. A ram lock according to Claim 2 wherein the hinge is formed by cylindrical tubes which are integral with or welded to the semicylindrical shells and a hinge pin which interconnects the tubes to form a hinge, means being provided to protect the ends of the hinge pin when the ram lock is in its operative position.

4. A ram lock according to any preceding claim which the inter-engaging component comprise a pair of semi-cylindrical lock shells, each lock shell being integral with or secured to one of the semi-cylindrical shells along mating longitudinal edges thereof.

5. A ram lock according to Claim 4 wherein, when the ram lock is in its operative position, the free edges of the semi-cylindrical lock shells abut each other.

6. A ram lock according to Claim 5 wherein each lock shell has secured thereto one or more bushes, the arrangement being such that when the ram lock is in its operative position the

bushes are housed within the cylindrical passage formed by the mating semi-cylindrical lock shells.

7. A ram lock according to Claim 6 wherein the bushes have apertures which are aligned when the ram lock is in its operative position and wherein a pin is provided to pass through the bushes to secure the semi-cylindrical lock shells together when the ram lock is in its operative position.

8. A ram lock according to Claim 7 wherein the pin is part of an assembly comprising the pin and a lock for locking the pin in its operative position, the assembly of the pin and the lock being removable from the ram lock to facilitate removal of the ram lock from its operative . position.

9. A ram lock according to Claim 8 wherein, when the bushes are locked together, they substantially fill the interior of the semi-cylindrical lock shells.