Jacking assembly

Abstract

A jacking assembly for moving a load, in steps, axially of a pipe comprises two pawl boxes having lateral platens and which are mounted at axially spaced positions on the pipe. The pawls of the boxes slope towards the pipe and exert a grip on it which allows relative movement between the boxes and the pipe to occur in one direction only. Inflatable hoses connected to a low pressure water supply are sandwiched between the platens and exert a thrust, when dilated, which increases nonlinearly with water pressure, to move whichever of the pawl boxes is carrying the load. This movement, which provides the working stroke, is followed by a recovery stroke during which the pawl box not carrying the load is moved up to the other pawl box under the action of springs or a second inflatable hose. The assembly is able to lift a heavy load with a low pressure water supply and has no moving seals. Its operation in parallel with other such assemblies is also described for house building and slip forming purposes.

I claimed: .[.1. A fluid operated jacking assembly suitable for moving a load, in steps, axially of an elongated member the assembly comprising: 
     
        in unison to lower the roof onto the top of the wall..]. .[.16.  An assembly as claimed in claim 1, in which the fluid pressure operated thrusting equipment comprises hose sections arranged one each side of the position of the longitudinal axis of the member and having their longitudinal axes arranged in a plane perpendicular to that of the axis, the hose sections being each doubled back on itself and around respective marginal portions of a separation plate which is freely moveable between the two parts and separates the two doubled-back portions of each hose section so that they do not bear on one another when dilated, means being provided for maintaining a fluid path between the two doubled-back portions of each hose section when the hose is flattened..]. .[.17. An assembly as claimed in claim 1 in which each part is of cruciform configuration when viewed in the direction of elongation of the member and is provided with two pawl pairs arranged perpendicularly to one another and being shaped to engage around the member at nearly the same position along its length so that the member, at that position, is subjected to substantially balanced, radially inwardly directed, thrusts from the pawls..]. .Iadd. 18. A fluid operated jacking assembly suitable for moving a load, in steps, axially of an elongate member having a substantially constant cross section, the assembly comprising: said elongate member, two parts adapted to be slidably mounted at axially spaced positions on the member;   pawl devices mounted on each of said parts and engagable with the elongate member in a way which permits relative axial movement in one direction only between the elongate member and said parts;   fluid-pressure operated means for forcibly separating the two parts in response to admission of a pressurised fluid to said means during a working stroke, said means comprising at least one inflatable bag located between and in contact with the two parts and, in operation of the jacking assembly, adjacent the elongate member, the bag being flexible but non-elastic so that the area of contact of the bag with the two parts diminishes progressively with increasing admission of pressurised fluid and consequential dilation of the bag, and   recover means for forcing the two parts towards one another to execute a recovery stroke following the working stroke, and release of fluid pressure from said fluid pressure operated means. .Iaddend..Iadd. 19. An assembly as claimed in claim 18, in which said bag comprises tubular hose means having a longitudinal axis which lies in a plane perpendicular to the axis of the elongate member. .Iaddend. .Iadd. 20. An assembly as claimed in claim 19, in which said bag comprises two lengths of hose connected hydraulically in parallel, in which said parts of the assembly have respective pairs of platens, and in which each of said hose lengths lies between two of said platens at opposite sides of the elongate member and with its axis in a plane perpendicular to the elongate member, and having means for admitting said pressurised fluid to said bag, said admitting means being attached to said bag and separate from two parts. .Iaddend..Iadd. 21. An assembly as claimed in claim 20, in which said hose lengths each have opposite end-portions which extend beyond the ends of said platens and each said platen is provided with adjustable extension means to vary the length of the platen in contact with the hose length. .Iaddend..Iadd. 22. An assembly as claimed in claim 21, in which said recovery means includes a coiled tension spring connected between the two parts. .Iaddend..Iadd. 23. An assembly as claimed in claim 18, including a carrier rigidly connected to one of said parts and lying on the opposite side of the other of said parts to said one part, and said recovery means comprises an inflatable element located between said carrier and said other part whereby inflation of the element forces said other part towards said one part to expel fluid from said bag during said recovery stroke. .Iaddend..Iadd. 24. An assembly as claimed in claim 23, in which the inflatable element comprises a hose portion having a longitudinal axis lying in a plane perpendicular to the longitudinal axis of said elongate member. .Iaddend..Iadd. 25. An assembly as claimed in claim 18, in which each of said pawl devices comprises a pawl box defining aligned openings through which said elongate member passes and having platens which extend laterally away from opposite sides of each said pawl box, said bag comprising at least one tubular hose lying in a plane perpendicular to the longitudinal axis of said elongate member and sandwiched between said two parts, arranged to bear on said platen portions thereof. .Iaddend..Iadd. 26. An assembly as claimed in claim 25, in which the pawl box contains pawls, and springs which are provided for said pawls for urging them to positions at which their ends engage opposite sides, respectively, of the elongate member at opposite positions, the lengths of said pawls being such that they make substantially the same acute angle with the longitudinal axis of the elongate member, and in which each pawl is provided with a rigid switch arm extending through an opening in the pawl box which is movable from outside the pawl box to disengage said each pawl from said elongate member. .Iaddend..Iadd. 27. An assembly as claimed in claim 26, in which said pawls comprise flat steel plates each formed at one end with an arcuate, sharp concave edge to grip the periphery of a circular section said elongate member, and which assembly also comprises abutment walls in said pawl box, abutment hinges formed at the opposite end of each said pawl from said concave edge by the engagement of each said pawl opposite end with respective said abutment walls, and slant-cut corner edges at each said one end of said pawls; in which assembly the width of each said pawls is sufficiently small for there to be a clearance between the sides of each said pawl and the inside of the pawl box to enable each said pawl to slew during controlled lowering of the assembly, the pawl box also being provided with catches for engaging with said switch arms so as to hold the respective pawls in positions whereby they are disengaged from said elongate member during lowering. .Iaddend..Iadd. 28. An assembly as claimed in claim 18, arranged in "-back-to-back-" combination with a second similar assembly, clamping means connecting together the adjacent said parts of the respective assemblies, control means being provided to enable said parts of the two assemblies to be selectively effective, and the fluid pressure operated means of the two assemblies being connected for parallel inflation and deflation. .Iaddend..Iadd. 29. An assembly as claimed in claim 18, in combination with a pair of telescopically arranged pipes of which the smaller diameter pipe comprises said elongate member and is engaged by the pawl devices while the larger diameter pipe provides a support for the assembly, whereby operation of the assembly extends the smaller diameter pipe in steps from the larger diameter pipe to provide a telescopically extendible strut. .Iaddend..Iadd. 30. An assembly as claimed in claim 18, including guides which prevent the two said parts from twisting with respect to one another, and adjustable stops between the two parts which allow them to separate and come together to predetermined adjustable extents. .Iaddend..Iadd. 31. An assembly as claimed in claim 18, mounted on a vertical pole constituting said elongate member arranged parallel to other vertical such poles each having a similar operating assembly mounted on it, the fluid pressure operated means of the assemblies being hydraulically connected for parallel operation in a closed water circuit which includes a pump and a reservoir tank. .Iaddend..Iadd. 32. An assembly as claimed in claim 18, in which the fluid pressure operated means comprises hose sections arranged one each side of the longitudinal axis of the member and having their longitudinal axes arranged in a plane perpendicular to that of the axis, the hose sections being each doubled back on itself and around respective marginal portions of a separation plate which is freely movable between the two parts and separates the two doubled-back portions of each hose section so that they do not bear directly on one another when dilated, means being provided for maintaining a fluid path between the two doubled-back portions of each hose section when the hose is flattened. .Iaddend..Iadd. 33. An assembly as claimed in claim 18, in which each said part is of cruciform configuration when viewed in the axial direction of said elongate member and is provided with two pawl pairs arranged perpendicularly to one another and being shaped to engage around the elongate member at nearly the same position along its length so that the member, at that position, is subjected to substantially balanced, radially inwardly directed, forces from the pawls. .Iaddend.