GB2279030A - Lifting device - Google Patents

Abstract

A lifting device, for example for lifting kerbs, comprises jaws (1, 3, 5, 7) for engaging with the kerb to be lifted, the jaws being pivotable 15 so as to be movable towards and away from the kerb to be lifted. A pair of handles (19) are provided for lifting the kerb, the handles being operably connected with the pivotable jaws for pivoting them. A releasable locking device (29, 31) releasably locks the lifting device in a position in which the jaws are engaged with the kerb. The handles are provided with resilient grips 23 at their free ends. Each handle is made up of an upper 27 and a lower 25 part which a slidably adjustable. The jaws have clamp members 11 at their ends to engage an object to be lifted. <IMAGE>

Description

LIFTING DEVICE The present invention relates to a lifting device and more particularly is concerned with a lifting device that incorporates pivotable jaws for engaging with an object to be lifted, such as a kerb, handle means for lifting the object, and releasable locking means for releasably locking the lifting device in a position in which the jaws are engaged with the object to be lifted.

Kerbs are usually lifted into their final position by two workers who are required to bend down, to incline the kerb in order to be able to grip underneath the kerb, and then to lift the kerb in order to move the same to its intended position. The risk of injury to the workers is considerable. Common injuries include injuries to the hands, especially the fingers, as a result of trapping beneath the kerb and injuries to the back as a result of the need to bend and subsequently straighten the back in order to be able to move the kerb to its intended position.

There is, therefore, a need for a lifting device which avoids the need for the workers to position their hands or fingers beneath the kerb and which enables the workers to lift the kerb without bending their backs.

It is therefore an object of the present invention to provide a lifting device which enables workers safely to lift kerbs and other objects without the need to position their hands or fingers beneath the object and without the need to bend their backs.

According to the present invention there is provided a lifting device comprising: jaws for engaging with an object to be lifted, the jaws being pivotable so as to be movable towards and away from an object to be lifted; handle means for lifting the object, the handle means being operably connected with the pivotable jaws for pivoting the same; and releasable locking means for releasably locking the locking device in a position in which the jaws are engaged with the object.

The present invention therefore provides a lifting device which is able to engage with an object, such as a kerb, thus avoiding the need for a worker to position his hands or fingers beneath the kerb. The lifting device is additionally provided with releasable locking means for releasably locking the device in a position in which the device is engaged with the object, thus avoiding the need for a worker to hold the device in its engaging position.

Finally, the lifting device is provided with handle means which enables the object to be lifted without any need for the worker to bend his back.

The jaws may be pivotably mounted at opposite ends of a pivot beam.

The jaws may be provided with a member for engaging the object to be lifted. The member may engage with the object by means of friction. The member may be made of a resilient material.

The handle means may comprise two handles. The handles may be pivotably mounted on the jaws.

The length of the handle means may be adjustable.

The releasable locking means may comprise means for pivotably securing the two handles together, the arrangement being such that, as the handles are pivoted so as to move the jaws together in order to engage with the object, as the handles are pivoted the jaws are first moved together and on further pivoting movement of the handles the jaws are subsequently moved apart. Stop means may be provided to restrict subsequent movement of the jaws apart.

The stop means may comprise part of the handles. The releasable locking means may be positioned at or towards that end of each of the handles adjacent to the jaws. The releasable locking means may be released by moving the handles apart.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 is an elevational view of one embodiment of a lifting device according to the present invention; and Figure 2 is a perspective view of the lifting device shown in Figure 1.

The lifting device shown in Figures 1 and 2 comprises a pair of jaws formed by a first pair of substantially parallel jaw members 1, 3 and by a second pair of substantially parallel jaw members 5, 7. Each pair of jaw members is secured together by any suitable means, for example by means of clamp supporting members 9 which extend generally perpendicularly across each pair of jaw members and which may be secured to the jaw members by means of welding or any other suitable means. Each clamp supporting member is provided on that portion thereof which opposes the other clamp supporting member with a clamp member 11 for frictionally engaging the object to be lifted. The clamp members may be made of a resilient material, such as a hard resilient rubber or plastics material.

The pairs of jaw members are pivotable about opposite ends of a pivot beam 13 which extends between the pairs of jaw members. In the illustrated embodiment, the pivot beam extends between the jaw members of each pair and is pivotable relative thereto by means of a nut and bolt arrangement 15 passing through one of the jaw members, through the pivot beam, and thereafter through the other of the jaw members.

At that end of each pair of jaw members remote from the clamp supporting members 9, the ends of each pair of jaw members are joined together by means of a handle supporting arm 17 which is secured at one end thereof to the jaw members of one pair and which extends towards the jaw members of the other pair. The two handle supporting arms 17 therefore extend towards each other, but are of such a length that they are spaced from each other at the free ends thereof.

Pivotably mounted at the free end of each of the handle supporting arms 17 is a respective handle 19. The handle 19 may be pivotably mounted on the handle supporting arm by means of a nut and bolt arrangement 21. The handles 19 extend generally away from the clamp members 11 and are curved or bent outwardly to facilitate lifting by a worker.

If desired a resilient grip 23 may be provided at the free end of each handle.

In the illustrated embodiment, the handles are adjustable so as to be adaptable to workers of different heights. As shown in Figures 1 and 2, each handle 19 comprises a lower handle member 25 which is slidably arranged within an upper handle member 27. The lower and upper handle members are provided with suitable adjusting means such as a plurality of spaced holes through the upper handle member which are able to register with a hole provided through the lower handle member, together with a securing mechanism which extends through the selected hole through the upper handle member and through the hole provided through the lower handle member in order to lock the handles at the selected position.

In the region of the lower end of each handle, there is provided a tie member 29. The tie member of one handle overlaps the tie member of the other handle such that the two tie members extend adjacent to one another, and the two tie members are pivotally secured to each other, for example by a nut and bolt arrangement 31. The pivotable tie members comprise a locking arrangement of the lifting device for locking the device with the clamp members frictionally engaged with an object to be lifted. In the illustrated embodiment this is accomplished by means of an over-centre arrangement that will be described in more detail hereinafter.

In use of the lifting device according to the present invention, two of the lifting devices are employed to lift an object such as a kerb. The handles 19 of the lifting devices are pivoted to move the handles apart. This in turn causes the clamp members 11 of the jaws to move apart and permits the lifting device to be lowered over a kerb such that one clamp member 11 is positioned on each side of the kerb.

The handles 19 are then moved towards each other and this in turn causes the clamp members 11 to move towards each other and to engage frictionally with opposing surfaces of the object. However, movement of the clamp members 11 is additionally controlled by the configuration of the pivoted tie members 29 such that, once the clamp members 11 have moved together to a predetermined separating distance, further movement of the handles 19 towards each other thereafter causes the clamp members 11 to move apart once again. The reason for this is that as the handles are moved together from a spaced apart configuration, the pivot point of the tie members moves progressively towards the pivot beam 13. This in turn, moves the lower ends of the handles apart because the tie members 29 are moved progressively towards a rectilinear configuration.

Nevertheless, once the tie members 29 have achieved a rectilinear configuration, further movement of the handles 19 towards each other will subsequently cause the lower ends of the handles once again to move towards each other and in turn will cause the clamp members 11 to move apart.

In the illustrated embodiment, subsequent movement of the clamp members 11 apart during movement of the handles together is limited by contact between the handles 19 which prevents further movement of the handles and which ensures that frictional contact between the object and the clamp members 11 is maintained at a satisfactory level. However, alternative stop means can be provided if desired. The tie members 29 are positioned towards the pivoted ends of the handles 19 such that a relatively large movement of the handles results in relatively small movement of the jaws.

This lever action assists in maintaining frictional contact between the clamping members 11 and the object and ensures that the over-centre locking mechanism is effective.

Once the lifting device has been engaged with the object, frictional forces will maintain the lifting device in position until such time as the handles 19 are moved apart.

It may be desirable for those portions of the handles that are gripped by the worker to be inclined in such a way (as illustrated) that lifting movement tends to move the handles towards each other.

With the lifting device in position, or separately if desired, the elevation of the handles can be tested for suitability and altered if desired using the adjusting means previously described. When the lifting device is satisfactorily positioned and adjusted, the object can be lifted by the worker bending his knees prior to lifting without the need for the worker to bend his back. As is well known, this manner of lifting heavy objects is far safer than is lifting by bending the back. Additionally, there is no need for the worker to position his hands or his fingers beneath the object thereby eliminating the risk of injury.

Once the object has been lifted, it can be carried to its intended destination and can then be lowered and positioned precisely as required. Once the object has been positioned, the lifting device is released by moving the handles 19 apart and the workers can then move another object to its intended destination.

Clearly, numerous modifications may be made to the lifting device as described above. For example, the frictional engagement can be replaced by some form of mechanical engagement between the lifting device and the object, although this may have the effect of limiting the range of applicability of the lifting device. In order to be able to adapt the lifting device to objects of differing widths, the spacing between the jaws may be adjustable. One way of effecting adjustment of the jaws would be to make the length of the pivot beam 13 adjustable, for example by means of a sliding sleeve arrangement such as that described above in respect of the handles 19.Other ways of effecting adjustment include, for example, adjustability of the lengths of the handle supporting arms 17 or the tie members 29, adjustment of the elevation of the pivot beam 13, adjustment of the positions of the clamp members 11 or interchangeability of one set of clamp members 11 for an alternative set having differing dimensions. As an alternative to adjusting the height of the lifting device by adjusting the handles, it is possible to adjust the lengths of the jaw members. One potential difficulty in the use of the lifting device according to the invention is that the number of pivot points can lead to an apparent instability of the lifting device.This potential difficulty is one of perception rather than a real problem, but can be overcome for example by positioning the handle supporting arms 17, or a part thereof, so as to be slidable within a suitable sleeve arrangement. Further, although the lifting device according to the present invention has been described and illustrated in connection with an overcentre locking arrangement, other forms of releasable locking arrangements can be provided. For example some form of releasable interlocking arrangement may be provided between the two handles, such as a releasable ratchet arrangement, or each of the handles may be connected to a further member by way of releasable locking means. The materials of the lifting device can be selected such that the pivot mechanisms, that is the nut and bolt arrangements as described, are less resistant to wear than the adjacent components. In this way, maintenance of the lifting device can be effected by replacing worn pivot mechanisms, thereby extending the overall service life of the device.

Claims (14)

1. A lifting device comprising: jaws for engaging with an object to be lifted, the jaws being pivotable so as to be movable towards and away from an object to be lifted; handle means for lifting the object, the handle means being operably connected with the pivotable jaws for pivoting the same; and releasable locking means for releasably locking the lifting device in a position in which the jaws are engaged with the object.

2. A lifting device as claimed in claim 1, wherein the jaws are pivotably mounted at opposite ends of a pivot beam.

3. A lifting device as claimed in claim 1 or 2, wherein the jaws are provided with a member for engaging the object to be lifted.

4. A lifting device as claimed in claim 3, wherein the member engages with the object by means of friction.

5. A lifting device as claimed in claim 3 or 4, wherein the member is made of a resilient material.

6. A lifting device as claimed in any preceding claim, wherein the handle means comprises two handles.

7. A lifting device as claimed in claim 6, wherein the handles are pivotably mounted on the jaws.

8. A lifting device as claimed in any preceding claim, wherein the length of the handle means is adjustable.

9. A lifting device as claimed in any preceding claim, wherein the releasable locking means comprises means for pivotably securing the two handles together, the arrangement being such that, as the handles are pivoted so as to move the jaws together in order to engage with the object, as the handles are pivoted the jaws are first moved together and on further pivoting movement of the handles the jaws are subsequently moved apart.

10. A lifting device as claimed in claim 9, wherein stop means is provided to restrict subsequent movement of the jaws apart.

11. A lifting device as claimed in claim 10, wherein the stop means comprises part of the handles.

12. A lifting device as claimed in any one of claims 9 to 11, wherein the releasable locking means is positioned at or towards that end of each of the handles adjacent to the jaws.

13. A lifting device as claimed in any preceding claim, wherein the releasable locking means is released by moving the handles apart.

14. A lifting device substantially as hereinbefore decribed with reference to, and as shown in, the accompanying drawings.