Climbing Mast Assembly

Field of the invention

This invention relates to a climbing mast assembly that is useful in multi-storey building construction, for example, for lifting or jumping concrete formwork frames or perimeter screens.

Background of the invention

It is established practice in the construction industry when erecting concrete cores or pillars of multi-level buildings, to employ a climbing formwork which is temporarily held to a lower, cured part of the structure while its formwork is employed in the formation of the next, uppermost level of the structure. The formwork is periodically "jumped" to the next level by connecting the formwork to the structure at a higher level, disengaging the supports at the lower level and moving the formwork upwards.

In the most basic system, a crane is used to effect the jumping step. In a system known as the Lubeca™ system, linked sections of the formwork are moved upwardly by heavy duty jacks. This latter system is particularly suitable for erecting cores or pillar groups of high rise buildings but is somewhat over engineered for smaller structures. For those cases, a known system for eliminating the use of a crane involves the temporary installation of a mast between the building floors to be jumped. The mast includes a multiplicity of holes spaced every 40 millimetres or so along the mast. The formwork is jumped up the mast from hole to hole by a system of jacks. Such a system is, however, laborious and time consuming, taking about 4 hours to jump a single formwork segment up its mast to the next working level.

In the case of perimeter screens, used to guard and protect the edges of floors of buildings as the floors are being constructed, each screen typically has two beams temporarily held to a completed floor by a large bolt at the inner end. These beams are termed "needles" in the building industry and take the weight of the screens. Prior to connecting the crane to the screens a second level of needles is located on the new

level above. Once the crane has taken the load of the perimeter screen all of the needles on the lower level are unbolted and removed by workers and manually transported two levels up, prior to raising the screen.

A limitation of the use of crane systems is that cranes can only operate in wind speeds up to a set maximum, eg 21 m/s, which can be somewhat limiting in areas of regularly higher wind speeds.

It is therefore an object of the present invention, in at least one set of applications, to provide an improved arrangement for jumping formwork frame or perimeter screens that is especially adaptable to smaller scale building works.

Summary of the invention

According to a first aspect, the invention provides a climbing mast assembly, including:

a mast having multiple recesses thereon spaced longitudinally along the mast;

a pair of ratchet housings mounted to be relatively slideable along the mast and including means to mount one or more jacks for coupling the housings and operable to adjust the relative separation of the housings along the mast;

first ratchet elements mounted on the respective ratchet housings for reciprocatory movement sliding movement, transversely of the mast, and selectively positionable to successively engage said recesses to limit return travel of the respective housing as it is advanced up the mast by operation of said jack(s); and

second ratchet elements mounted on the respective ratchet housings for reciprocatory movement sliding movement, transversely of the mast, and selectively positionable to successively engage said recesses to allow lifting of the mast by the jack(s) and to limit return travel of the mast when it is being raised relative to the respective housings.

The mast is conveniently a tubular beam, for example of a rectangular or preferably square cross-section, in which the multiple recesses are formed as opposed pairs of apertures.

The means to mount one or more jacks for coupling the housings preferably comprises two pairs of cooperating mounts for providing a pair of similar jacks to opposite sides of the mast.

The assembly may include the jack(s). Where a pair of jacks is provided, in use they are preferably hydraulically linked for equal oil flow from a power pack, thereby ensuring a balanced and symmetric operation about the mast.

The assembly typically may further include frame members for mounting one of the ratchet housings to a structure to be raised by the climbing mast assembly. Such frame members may include a pair of columns to either side of the mast along which the other ratchet housing is slideable. For use in a typical installation, these columns depend from the ratchet housing that, in situ, is uppermost. Advantageously, the columns of the frame members are arranged at a 90 degree angular spacing about the mast with respect to the jack positions.

The first and second ratchet elements are preferably of similar shape and dimensions with an at least partially oblique trailing edge on a projecting portion. This portion typically further has a detent face aligned substantially at right angles to the longitudinal axis of the mast. These similar ratchet elements serve as first or second ratchet elements by virtue of their oppositely mounted, or relatively inverted, orientation.

Means is preferably provided for effecting said selectively positionable feature of the ratchet elements by slideably moving them between a forward operative position in which they engage the mast recesses but are retractable against bias means in one relative direction of travel, and a retracted inoperative position.

Preferably, the first and second ratchet elements include a rear face from which projects a link rod. Each link rod may be eccentrically pinned to a cylindrical cam at one end of the cam lever. If the cam lever is swung through 180°, the respective ratchet element

may be moved between the forward operative position and the retracted inoperative position.

According to a second aspect, the invention provides a climbing mast assembly, including:

a central mast having multiple recesses thereon spaced longitudinally along the mast;

a pair of ratchet housings mounted to be relatively slideable along the mast and including means to mount one or more jacks for coupling the housings and operable to adjust the relative separation of the housings along the mast;

first ratchet elements mounted on the respective ratchet housings for reciprocatory movement, relative to the mast, and selectively positionable to successively engage said recesses to limit return travel of the respective housing as it is advanced up the mast by operation of said jack(s);

second ratchet elements mounted on the respective ratchet housings for reciprocatory movement, relative to the mast, and selectively positionable to successively engage said recesses to allow lifting of the mast by the jack(s) and to limit return travel of the mast when it is being raised relative to the respective housings; and

a pair of wallforms suspended below the central mast for advancement with the ratchet housings, for use in casting of a subsequent wall or column therebetween.

The reciprocatory movement of the ratchet elements is preferably a sliding movement transversely of the mast.

Typically, the frame members depend from the ratchet housing that, in situ, is uppermost. Advantageously, the frame members include outer uprights, the lower ends of which are braced by inwardly directed cantilevered beams that mount wheels for rotatably engaging the outer face of the wall or column during the jumping process. The

outer uprights may be linked by a cross-beam structure, upon which working platforms may be mounted.

The columns of the frame members are preferably arranged at a 90 degree angular spacing about the mast with respect to the jack positions. In situ, the central mast is preferably positioned to be aligned with, and lie directly above, a respective wall or column.

The mast may have a detachable base plate for casting into the top of the wall or column and for supporting the mast when the ratchet housings are advanced upwardly. The assembly is typically supported by retractable needles that engage with the wall or column.

According to a further aspect, a climbing formwork structure is provided, including two climbing mast assemblies, according to the first or second aspect, to form two adjacent walls or columns.

According to another aspect, a method of forming a wall or column is provided, including:

positioning a climbing mast assembly according to the first or second aspect, such that the mast is aligned with, and lies directly above, a cast section of a respective wall or column;

positioning said first ratchet elements in an operative position and said second ratchet elements at a withdrawn position;

actuating the jacks to push the upper ratchet housing upwardly and advance the wallforms up the mast;

retracting the jacks to elevate the lower ratchet housing upwardly;

positioning said first ratchet elements at a withdrawn position and said second ratchet elements in an operative position;

operating the jacks to lift the mast upwardly; and

casting between said wallforms a further section of said wall or column atop said cast section.

Brief description of the drawings

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a front elevation for an exemplary climbing formwork structure to which are fitted a pair of climbing mast assemblies according to an embodiment of the invention;

Figure 2 is a vertical axial cross-section of one of the climbing mast assemblies, on the line 2-2, in Figure 1 , in which the hydraulic jacks are omitted;

Figure 3 is a somewhat schematic plain view of the horizontal cross-section on the line 3-3, in Figure 2, of one of the opposed pairs of ratchet housings of the mast assembly; and

Figures 4 and 5 are pairs of more detailed views of a ratchet element and a cam lever respectively.

Detailed description of the embodiments

Before describing in detail an embodiment of a climbing mast assembly according to the invention, a typical application of the assembly will be described with reference to Figure 1. Figure 1 illustrates a climbing formwork structure 10 being employed to progressively erect a pair of spaced concrete columns or walls 12. The main frame 14 of steel girders has outer uprights 16, 17 linked by main cross-beams 18 that are in turn linked horizontally by two pairs 20 of spaced back-to-back square channel beams 22. These beams are centred on or aligned with, and lie just above, the columns 12. Upper working platforms 24 are mounted on main cross-beams 18 between and to the outside of main beam pairs 20.

Suspended from cross beams 18 are two pairs of wallforms 26 that are suitably reinforced, braced and stabilised and between which the upper-most segments of column 12 have just been cast. Below these segments, the structure 10 is supported on the columns in a known manner by retractable "needles" 28 that rest in matching cavities 29 cast in the columns 12. On the outside of the columns 12 at this level, the lower ends of uprights 16, 17 are braced to the columns 12 by inwardly directed cantilevered beams 30 that mount wheels 32 for rotatably engaging the outer face of the column 12 during the jumping process. Lower working platforms 34 are also provided on these cantilevered beams 30 and between the columns.

For jumping structure 10 to a higher level for the purpose of casting the next segments of columns 12, a number, typically four, of climbing mast assemblies 40 are mounted atop main beam pairs 20. Each climbing mast assembly 40 includes a central mast 42 in the form of a tubular square-section beam, and a pair of similar vertically spaced ratchet units 50, 51 that embrace the mast. The upper ratchet unit 50 is fixed to, and at an elevated position above, channels 22, by respective channel section columns 52 to opposite sides of mast 42, while lower ratchet unit 51 is vertically moveable along columns 52 but coupled to upper ratchet unit 50 by a pair of hydraulic jacks 55. Jacks are also disposed to opposite sides of mast 42 but angularly displaced by 90 degrees from columns 52. Columns 52 are linked and braced midway by a pair of side plates 53, and fastened to the respective channel beams 22 by foot-plates 54 welded to the columns and bolted in situ to the beams.

In operational use of the climbing mast assemblies 40, each mast 42 has a base plate 43 that is cast in situ and thereby mounted atop a respective column 12, as illustrated in Figure 1. The mast projects upwardly in a close sliding fit between channel beams 22, and is formed with a multiplicity of equispaced opposed rectangular apertures 45, typically set, for example, at 275mm spacing. These apertures are, in operation, selectively engaged by ratchet elements 60a, 60b (shown in Figure 2) that are slideable horizontally in ratchet units 50, 51.

Ratchet elements 60a, 60b are all of similar form but are arranged in four pairs: each ratchet unit has a pair of ratchet housings 56 on the same sides of the mast as the

hydraulic jacks 55, and each housing in turn has a pair of side-by-side ratchet elements 60a, 60b of relatively inverted orientation. The housings are coupled by side plates 69. First ratchet elements 60a consist of a flat plate 61 with a rear edge face 62 from the centre of which projects a cylindrical link rod 63. At the front edge is an integral protruding portion 64 of similar thickness but reduced height having a front face 65 parallel to the axis of rod 63 and perpendicular to the axis of mast 42, and an oblique trailing face 66. Ratchet element 60a is a close sliding fit in matching rectangular housing 56 with face 65 facing downwards, while ratchet element 60b is similarly mounted but with face 65 facing upwards. The two ratchet elements are separated by and engage a vertical rotatable pin 68 to facilitate their sliding movement while keeping them apart.

Each rod 63 projects from the rear of housing 56 where it is eccentrically pinned to a cylindrical cam 70 at one end of a cam lever 72. Cam 70 engages the rear face of housing 56 and so if lever 72 is swung through 180°, the respective ratchet element is moved between a forward operative position in which protruding portion 64 can project from the open front 57 of housing 56 into the path of the mast, and a withdrawn position within the housing 56. A helical compression spring 75 between the rear edge face 62 of each ratchet element 60 and the rear wall of housing 56 biases the ratchet element outwardly but the spacing occupied by the spring is reduced by swinging lever 72 to the withdrawn position.

To achieve proper force balance, ratchet elements 60a on one side of the mast are positioned opposite ratchet elements 60b on the other. Hence, in the view of Figure 2, the ratchet elements 60a on the left are in their operative position, while the ratchet elements 60b on the right are in their withdrawn position: the different positions of the cam levers 72 will be noted.

It has already been observed that lower ratchet units 51 are coupled to the ratchet units 50 by hydraulic jacks 55. Figure 2 depicts the brackets 80 atop lower housings 56 and underneath upper housings 56 to which the jack pistons and cylinders are respectively mounted in operation, although the jacks are omitted from this view.

The operation of the climbing mast assemblies will now be described. Figure 1 depicts the situation at the completion of curing of the most recently cast sections of columns 12, and it is therefore time to jump the structure 10 to the next level ready for casting the next segments of the columns. Ratchet segments 60a are set in the operative positions and ratchet segments 60b in the withdrawn positions, the condition shown in Figure 2.

Needles 28 are disengaged whereupon the load of structure 10 is taken by the operative ratchet elements and hence by ratchet housings 56. The mounting of the ratchet elements in the housings should be suitably load-rated: this is achieved in part by the close fitting sliding fit of the ratchet elements in sufficiently strong rectangular housings.

The jacks 55 are actuated in extension mode to push the upper ratchet units 50 upwardly and thereby lift the entire structure 10, including wallforms 26, via columns 52. Each ratchet element 60a of the upper ratchet unit will successively engage apertures 45 of the mast, retracting against spring 75 but jumping into each aperture in turn to thereby limit return travel of the respective ratchet housings 56, ratchet units 50 and thereby of the entire structure 10 as it is advanced up the masts 42 by the operating jacks 55. If the jacks fail, the structure falls no further than the spacing between apertures 45 before it is locked against further descent.

The jack throw is equal to multiple such aperture spacings, for example a total throw of 1.2 metres before it reaches its maximum extent. At that point, with the weight of the structure supported by upper ratchet elements 60a engaging respective apertures 45, the jacks are now retracted to elevate the lower ratchet unit 51 , ratchet elements 60 again moving in and out as they successively engage and are pushed back by apertures 45. This process is then repeated until the full jump height is reached, at which point needles 28 are extended again to rest on the top of the columns 12, or in other preformed recesses for this purpose on the columns.

The jumping process is then completed by raising the mast 42. To allow this to occur, the positions of the ratchet elements must all be reversed, with ratchet elements 60a being moved to their withdrawn positions and ratchet elements 60b to their operative

positions. When the jacks are retracted, lower ratchet elements 60b engage the mast apertures to lift the mast upwardly while upper ratchet elements 60b successively retract and extend as they successively engage the mast apertures. The reverse occurs when the jacks are extended and again should the jacks fail in some way, the mast cannot fall further than the spacing of apertures 45 before it is caught by the ratchet elements. Once the structure 10 has jumped to the next level, the climbing mast is positioned such that it is aligned with, and lies directly above, the previously cast column section 12. The wallforms 26 are now positioned to cast a further section of column 12.

The illustrated climbing mast assembly is of relatively simple construction and, as a complete and self contained unit, is readily adaptable to a variety of situations. The combination of the multi-recessed mast and the complementary sets of ratchet elements allows a single lift to be a substantial proportion of the total jump required, and yet safety is assured by having ratchet elements capable of carrying the load of the jumped structure with only a small vertical maximum slip equal to the spacing of the mast recesses.

The invention has been described herein in connection with a climbing formwork structure. In another application the climbing mast assembly may be employed to jump perimeter screens used to guard and protect the edges of floors of multi-storey buildings as the floors are being successively constructed.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

As used herein, except where the context requires otherwise the term 'comprise' and variations of the term, such as 'comprising', 'comprises' and 'comprised', are not intended to exclude other additives, components, integers or steps.