GB2243801A - Clamps - Google Patents

Abstract

A clamp 10 has clamping elements 11, 12 pivoted to cross-member 20. A rotatable shaft 24 extends through member 20 and carries a threaded collar 26. Arms 28 are pivoted to the elements 11, 12 and the collar 26. At least one of the pivots 21, 30 is a sliding pivot. Rotation of handle 25 causes the elements 11, 12 to move angularly relative to an article being clamped. The clamp may find use in lifting cores formed by drilling an annular slot in a layer of solid material. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO CLAMPS This invention relates to clamps.

According to this invention a clamp comprises two clamp elements arranged for clamping a member to be clamped, and means for moving the elements towards each other to clamp the member, the elements being mounted for angular movement relative to the member.

The moving means may comprise two supports pivotally connected to the elements at spaced locations, at least one of the pivotal connections permitting relative sliding movement.

One support may comprise arms pivoted to the elements and to structure between the elements, and means for moving the structure to move the elements towards or away from each other.

The structure may be a threaded collar on a rotatable shaft.

The shaft may be rotatable in the other support. The invention may be performed in various ways and one specific embodiment with possible modifications will now be described by way of example with reference to the accompany drawings in which: Fig. 1 is a perspective view of a lifting device; Figs. 2t - 2D show schematic stages in use of the device; and Fig. 3 shows a modification.

A gripping and lifting device 10 comprises two generally similar gripping or clamp members 11, 12 which are elongate and part-circular plates. Upper and lower brackets 13, 14 are fixed to the inner surfaces 15, 16 of each of the members 11, 12, the bracket 19 being near to the top and the bracket 14 approximately mid-way along the length of the member.

The brackets 13 have transverse elongate apertures 17 which each receive a bolt 18 passing through an aperture in a lug 19 depending from one end of a crossbar 20. The bolts 18 receive nuts 21 so that the lugs can be held to the brackets but relative movement can occur between the bolts 18 and the respective aperture 17.

A bearing 22 is secured centrally on the cross-bar 20 and rotatably receives an unthreaded upper end of a vertical shaft 23 having a lower threaded portion 24.

The shaft 23 can be rotated by a handle 25. The portion 24 receives a threaded collar 26 having wings 27. Rigid arms 28 have apertured ends which receive bolts 29, 30 extending respectively through apertures in wing 27 and bracket 14. The bolts 29, 30 receive nuts to hold the parts together but permitting pivotal movement.

Because the bearing 22 prevents axial movement of the shaft, rotation of handle 25 moves collar 26 up or down, If the collar 26 moves upwards, the arms 28 move nearer to the vertical and the lower ends of the plates 11, 12 are moved inwards towards each other, pivoting at bolts 18 and 30 and 29, so that the plates 11, 12 can move angularly.

Figs. 2A to 2D show one use of the device.

A concrete layer 40, e.g. a road surface, resting perhaps on soil 41 has an annular slot 42 drilled through it by a diamond-tip circular drilling bit 43.

The device 10 is used to remove the circular section core 44 which is thus cut out from the road 40.

The plates 11, 12 are lowered, for example by hand, into the slot 42 to a suitable depth, the handle 25 is rotated to raise the collar 26 and thus close the plates 11, 12. Vixen the lower ends of the plates 11, 12 engage the core 44 (Fig. 23), further rotation of the handle 25 causes sliding movement of bolts 18 in slots 17 to bring substantially the whole of the lower parts of surface 15, 16 into contact with the core 44 thus giving a good grip (Fig. 2C) the plates 11, 12 moving angularly relative to the core 44, and the device 10 with core 44 can then be raised (Fig. 2D).

Reverse rotation of the handle 25 releases the core 44.

The diameter of surfaces 15, 16 is selected to suit the diameter of the core 44.

The elements 11, 12 need not be part-circular but could be other shapes dependent on the shape of the article it is desired to raise.

In a modification the bars 28 are replaced by threaded bars 50 Fig. 3 which receive rotatable end bearings 51 so that the overall length of the bars 50 can be adjusted, and the bearings 51 can rotate on pins secured in brackets 14 and wings 27.

The operation of the described devices is to be contrasted with a method of raising the core 44 which involves drilling a hole in the top of the core to receive a bolt carrying a lifting eye for connection to the hook of a crane, which overall procedure is slow and cumbersome.

However, the device 10 could be raised by a crane if desired.

The height of the core 44 can vary and can be considerably more than that shown in the drawings; the centre of gravity of the core 44 could be substantially below the lower ends of the plates 11, 12.

One or both of the surfaces 15, 16 may receive a liner 15a to give an improved grip e.g. a liner of emery or other roughened paper.

Claims (7)

1. A clamp comprising two clamp elements arranged for clamping a member to be clamped, and means for moving the cements towards each other to clamp the member, the elements being mounted for angular movement relative to the member.

2, A clamp as claimed in claim 1, in which the moving means comprises two supports pivotally connected to the elements at spaced locations, at least one of the pivotal connections permitting relative sliding movement.

3. A clamp as claimed in claim 2, in which one support comprises arms pivoted to the elements and to structure between the elements, and means for moving the structure to move the elements towards or away from each other.

4. A clamp as claimed in claim 3, including means for adjusting the lengths of the arms.

5. A clamp as claimed in claim 3 or claim 4, in which the structure comprises a threaded collar on a rotatable shaft.

6. A clamp as claimed in claim 5, in which the shaft is rotatable in the other support.

7. A clamp substantially as hereinbefore described with reference to and as shown in Fig. 1, or Fig. 3, of the accompanying drawings.