A LIFTING CUSHION

Abstract: A liting cushion for raising or supporting heavy objects comprises inner and outer layers (2 and 24), and spacing members (16), all made of polyaramid cord and coated with neoprene. The inner layer (2) is folded over to provide two opposed major portions (6 and 8) having parallel opposed slits (14) therein. Generally U-shaped spacing members (16) extend through opposed slits (14) with facing end arms (18 and 20) of the spacing members (16) connected to the outer surfaces of the opposed major portions (6 and 8). The gaps between the spacing members (16) and the opposed major portions (6 and 8) are closed by strips of uncured rubber and neoprene. The folded over inner layer (2), the spacing members (16) and the strips are secured together by hot vulcanising. The folded over inner layer (2) is then placed in the centre portion of the laid out outer layer (24). This outer layer (24) is then folded over the inner layer (2) so that the end edges (28) of the outer layer (24) overlap one another. The assembly is then hot vulcanised to secure the components to one another to provide the finished lifting cushion.

Description: -1- A LIFTING CUSHION The present invention relates to a lifting cushion for supporting, raising or moving objects. Lifting cushions of the invention may for example be used for rescuing people who are trapped by collapsible walls, girders, concrete slabs or road vehicles. These lifting cushions can also be used for prising steering columns, removing windscreens and for forcing doors. Industrial uses of lifting cushions include lifting heavy machinery, rail locomotives and pipelines, supporting tensioning in mining, splitting slabs in quarries, and use as compression or spreader elements. In operation, the lifting cushion is placed in its flattened condition beneath the object to be raised, and the cushion is then inflated thereby raising the object. If further lift is required one or more lifting cushions may be inserted one above the other and subsequently inflated to provide a required degree of lift of the object. In order to provide a maximum lifting force lifting cushions are generally of rectangular form. With previously known lifting cushions the problem arises that when inflated the cushion changes from its non-inflated flat rectangular form to a form having a generally oval vertical cross-section. This change in shape of the cushion considerably reduces the contact area between the cushion area and the object to be raised thereby producing a corresponding reduction in the lifting force that can be applied by the cushion to the object. There is also the significant risk arising from the difficulty of calculating the force required to lift the object from -2 - the trapped person or to gain clearance to insert cribbage. It will be appreciated that this change of shape in the cushions makes it extremely difficult to provide sufficient stability to be able to use a plurality of cushions, one on top of the other. It is an aim of the invention to alleviate the above- mentioned disadvantages, and according to the present invention there is provided an inflatable lifting cushion comprising an inner layer extending in a first direction and folded over on itself with its folded end regions overlapping to define an inner pair of spaced opposed major portions, an outer layer extending in a second direction and folded around the first layer with its folded end regions overlapping to define an outer pair of spaced opposed major portions located on said first pair of spaced opposed major portions, and a plurality of spacing members located between said inner pair of spaced opposed major portions to retain said outer pair of spaced opposed major portions at a preselected attitude to one another when the lifting cushion is fully inflated. In a preferred embodiment of the invention the cushion is rectangular and the first and second directions of the layers are at 90° to one another and extend parallel to first and second sides of the cushion. Each spacing member may extend through opposed slits in the inner pair of spaced opposed major portions with opposed facing end portions of the spacing members connected to the outer surfaces of the said inner pair of spaced opposed major portions. In a preferred embodiment of the invention the two layers -3 - and the spacing members may be constructed of a polyaramid material such as polyaramid cord, and the first and second layers and the spacing members may be coated with an air retaining rubber compound such as neoprene . One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: - Figure 1 is a sectional elevation of part of a lifting cushion of the invention, and Figure 2 is a perspective view of the inner and outer layers of the lifting cushion of Figure 1. Referring to the drawings, a lifting cushion of the invention includes an inner layer 2 consisting of a rectangular sheet 4 made of polyaramid cord coated with a neoprene layer on both its upper and lower surfaces. The width and length of the sheet 4 are chosen to provide a lifting cushion of the required dimensions, and to provide an inner pair of spaced opposed major portions 6 and 8 with the sheet end edges 10 overlapping one another in the centre of the lifting cushion. The direction of reinforcement of the sheet 4 extends in the direction 12. Referring to Figure 1 opposed slits 14 extend along the length of the major portions 6 and 8 of the sheet 4 and these slits 14 end at a distance of 60mm from the curved end portions of the sheet 4. These slits 14 are spaced at 100mm from one another along the width of the major portions 6 and 8 of the sheet 4. -4- The major portions 6 and 8 of the sheet 4 are connected by a plurality of spacing members 16 which extend along the length of the major portions 6 and 8 in a direction perpendicular to the plane of Figure 1. These spacing members are of generally U-shaped cross-section when the cushion is fully inflated, and are made of polyaramid cord coated with an air retaining rubber compound such as neoprene. Each spacing member 16 consists of end arms 18 and 20 connected by a spacer portion 22, and is threaded through associated opposed slits 14 in the major portions 6 and 8 so that the end arms 18 and 20 extend along the outer surfaces of the major portions 6 and 8. When the cushion is deflated, the spacing members 16 are of generally V shaped cross-section with each spacer portion 22 folded along its centre line so that each end member 18 and 20 is parallel to its adjacent half of its associated spacer portion 22. Strips of uncured rubber/neoprene having the same length as the slits 14 and of L transverse cross-section are positioned against the inner opposed surfaces of the major portions 6 and 8 and spacer portions 22 of each spacing member to fill a gap left at the corners of each spacing member and its associated part of the major portions 6 and 8. Strips of melamine or other suitable barrier material are laid onto the inner surfaces of the major portions 6 and 8 to prevent these opposing inner surfaces sticking together during the hot vulcanising of the assembly when providing the finished lifting cushion. The surfaces of the sheet 4 and the spacing members 16 are coated with an air retaining rubber compound such as neoprene thereby enabling the components to be vulcanised -5- to the other components of the lifting cushion. An outer layer 24 consists of an outer rectangular sheet 26 which is made of polyaramid cord and is coated with a neoprene layer on both its upper and lower surfaces the same as the first sheet 4 except that all its directions and dimensions are rotated through 90°. The sheet 26 has the same width as the length of the folded sheet 4, and the length of the sheet 26 is chosen so that it can be wrapped round the inner layer 2 with its end edges 28 overlapping in the centre of the cushion. During manufacture, the inner and outer layers 2 and 24 are carefully pressed by a roller in order to prevent air from being trapped in the two layers . Any such trapped air would breathe during inflation and evacuation of the lifting cushion thereby producing unwanted separation of the components of the cushion. The inner layer 2, the spacing members 16, the L cross- section strips and the melamine strips are assembled as herein described, and the inner layer 2 is folded over so that its end edges 10 overlap one another in the centre of the lifting cushion. The rubber nipple of an air valve is inserted into one corner of the folded inner layer 2 with the attached nozzle of the air valve extending from the inner layer 2. The assembly is then hot vulcanised to secure the components to one another. The folded sheet 4 of the inner layer 2 is then placed on the centre portion of the laid out outer layer 24 which is located at 90° to the folded inner sheet 4. The sheet 26 of the outer layer 24 is then folded over the inner sheet 4 so that the two end edges 28 of the outer sheet 26 overlap one another on the -6- opposite face of the lifting cushion to the end edges 10 of the inner sheet 4. In this folded position an outer pair of opposed major portions 32 and 34 of the sheet 26 are located on the inner major portions 6 and 8 of the sheet 4. The direction of reinforcement 30 of the outer sheet 26 runs perpendicularly to the direction of reinforcement 12 of the inner sheet 4. The folded sheet 26 is hot vulcanised to secure the sheet 26 to the sheet 4 to produce the finished lifting cushion in which the sheets 4 and 26, the spacing members 16 and the rubber/neoprene strips become homogenous to close the slits 14.

Claims: -7 - CLAIMS 1. An inflatable lifting cushion comprising an inner layer extending in a first direction and folded over on itself with its folded end regions overlapping to define an inner pair of spaced opposed major portions, an outer layer extending in a second direction and folded around the inner layer with its folded end regions overlapping to define an outer pair of spaced opposed major portions located on the said inner pair of spaced opposed major portions, and a plurality of spacing members located between said inner pair of spaced opposed major portions to retain said outer pair of spaced opposed major portions at a preselected attitude to one another when the lifting cushion is fully inflated. 2. A cushion as claimed in claim 1 in which said first and second directions are at 90° to one another. 3. A cushion as claimed in claim 2 in which the cushion is rectangular and the first and second directions of the layers are parallel to first and second sides of the cushion. 4. A cushion as claimed in any preceding claim in which the spacing members extend between and through said inner pair of spaced opposed major portions. 5. A cushion as claimed in claim 4 in which each spacing member extends through opposed slits in the inner pair of spaced opposed major portions with opposed facing end portions of the spacing member connected to the outer surfaces of said opposed major portions. 6. A cushion as claimed in any preceding claim in which -8- the outer pair of spaced opposed major portions are parallel to one another when the envelope is inflated. 7. A cushion as claimed in any preceding claim in which the inner and outer layers and the spacing members are constructed of a polyaramid material. 8. A cushion as claimed in claim 7 in which the inner and outer layers and the spacing members are made of polyaramid cord. 9. A cushion as claimed in claim 7 or claim 8 in which the inner and outer layers and the spacing members are coated with an air retaining rubber compound. 10. A cushion as claimed in claim 9 in which the air retaining rubber compound is neoprene. 11. A cushion as claimed in claim 5 including strips of a rubber compound which are located to cover the gaps between the spacing members and the inner surfaces of the inner pair of spaced opposed major portions. 12. A cushion as claimed in claim 11 in which the rubber compound is uncured rubber and neoprene. 13. A cushion as claimed in any preceding claim including members of a suitable barrier material which are located on the inner surfaces of the inner pair of spaced opposed major portions to prevent the opposed surfaces sticking together during the hot vulcanising of the cushion. 14. A cushion as claimed in claim 13 in which the barrier material is melamine. -9- 15. An inflatable lifting cushion substantially as herein described and shown in the accompanying drawings,

Inventors: JONES DAVID BERNARD DI, JONES, DAVID, BERNARD DI
Applicants: JONES PHILIP LM, M F C SURVIVAL LIMITED, JONES, PHILIP LM, M.F.C. SURVIVAL LIMITED
Application year: 1999
Main classification: B66F3
IPC codes: B66F3