BACKGROUND ART Australian patent no. 620031 describes a machine for forming concrete kerbing. Wet concrete in a plastic state is fed into a hopper, and extruded onto the ground through a mould of desired cross sectional profile by a reciprocating pivoted pusher plate. The concrete extruded through the mould, when set, forms kerbing having a sectional profile matching that of the mould. Further, the reciprocating pusher plate serves not only to extrude concrete through the mould, but also to push the machine in the opposite direction. In this manner, the machine lays a moulded kerb as it propels itself along at the newly formed end of the kerb.

Although the machine described in patent no. 620031 operates effectively, it has been found that its construction and operation can be improved.

It is therefore an object of the present invention to provide an improved machine for extruding concrete or other settable materials.

SUMMARY OF THE INVENTION In one broad form, the present invention provides a machine for producing an elongate formation, such as a kerb or the like, by extruding concrete or other settable material in one direction through a generally tunnel-shaped mould member while moving in the opposite direction.

Preferably, the mould member has attachment means at both ends thereof by which it can be detachably mounted to the machine. Consequently, the reversible mould member enables the machine to form kerbing in either direction, even if the kerb has an asymetrical profile.

The machine typically has a body defining a hopper which communicates with a ramming chamber at an inlet end of the mould member. Removable side walls or skirts are suitably mounted at opposite sides of the ramming member to enable the machine to be used with mould members greater than standard height.

The machine has a steering assembly including at least one ground-engaging wheel. The steering assembly is adjustable in position laterally relative to the body of the machine, to enable the machine to be used in close proximity to a wall or other vertical obstacle. Locking means are preferably provided to lock the steering assembly in position relative to the body of the machine. Preferably, means are provided for locking each steerable ground-engaging wheel in a fixed orientation, to allow the machine to form kerbing in straight lines or kerbs of constant curvature.

Each wheel is preferably mounted on a respective telescoping leg assembly having upper and lower portions which are relatively rotatable about a common longitudinal axis. The wheel is mounted to the lower portion, while the upper portion is fixed relative to the body of the machine. The wheel locking means suitably comprises a locking member which passes transversely through one of the upper or lower members and engages the other member to thereby prevent relative rotation between them.

Typically, the machine has a pair of steerable wheels each mounted on a respective wheel mount. Each wheel mount has a steering arm, the steering arms being connected by a steering link assembly of adjustable length. The steering link assembly suitably comprises a link rod having left and right handed threads at its respective ends, thereby allowing the length of the steering link to be adjusted while it remains in place.

The concrete or other material is extruded through the mould member by pusher means. The pusher

means is preferably connected to a driving mechanism by a pusher rod assembly of adjustable length. The pusher rod assembly suitably comprises a connecting rod having left and right hand threads at its opposite ends, to enable the length of the pusher rod assembly to be adjusted while it remains in place.

The pusher means preferably comprises a pusher plate which is removably connected to a plate support member which, in turn, is pivotally mounted to the body of the machine.

The height of each leg assembly can be adjusted by rotating a handle at the top end thereof. Preferably, the handle is pivotally connected to the leg assembly so that it may be turned to an upright position. This enables the height of the leg assembly to be varied even when the machine is close to a wall or other vertical obstacle.

In order that the invention may be more fully understood and put into practice, a preferred embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view, from top and side, of a concrete moulding machine according to one embodiment of the invention;

Fig. 2 is a perspective view from top side rear, of the moulding machine of Fig. 1;

Fig. 3 is a sectional elevational view of the machine of Fig. 1 in use; and Fig. 4 is a perspective view of a detachable mould used with the machine of Figs. 1-3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

As shown in the drawings, the concrete moulding machine 10 is of the same general construction as the concrete moulding machine described in Australian patent no. 620031. The machine 10 comprises a hopper 11 in which wet concrete 12 of a desired consistency is loaded. The machine 10 also comprises a motor 26 which is belt-

coupled to a gearbox 27 having a crank arm 28 on its side-mounted output shaft 29. A push rod 29 is connected between a pusher plate 13 and the free end of the crank arm 28. The pusher plate 13 is hinged at its top end and is caused to pivot back and forth about its hinge axis.

When the pusher plate 13 is pulled towards the front of the machine (shown on the left in Fig. 3) , the concrete 12 in the hopper 11 falls under gravity into a ramming chamber at the front end of a mould member 15. When the pusher plate 13 is pushed to the rear of the machine (shown on the right in Fig. 3) , the concrete in the ramming chamber is pushed through the tunnel-shaped open-bottomed mould 15. The wet concrete is in a plastic state, and is extruded through the mould 15 to form a continuous kerb having a sectional profile matching that of the mould 15. The concrete retains that profile when set.

Further, when the pusher plate 13 is pushed towards the rear of the machine 10, the reaction of the newly extruded kerb to such motion causes the machine 10 to travel forwardly. The machine 10 therefore propels itself along the kerb as it is being formed.

The illustrated machine has several improved and/or advantageous features, and these are described in more detail below.

Moulds used with concrete kerb forming machines typically have a transverse sectional profile which is not symmetrical about a central longitudinal vertical plane. Thus, when laying kerbing with such asymetrical section, the machine can only be operated in one direction. In some situations, it may be necessary or desirable to lay the kerbing in the opposite direction. Known machines are not bidirectional.

To overcome the above problem, the machine 10 is provided with a double ended mould 15. The mould 15 is provided with mounting plates 16 (Fig. 4) at both ends thereof, allowing either end to be mounted to the machine 10. A kerb with asymetrical sectional profile may now be

laid in either direction, thereby enabling the machine to extrude kerbs in situations not previously possible.

The known kerb forming machine, described in Australian patent no. 620031, is designed to operate with a mould of standard height, typically 90mm. In some cases, it is desirable to form higher kerbing. However, if a taller mould were used, the sides of the ramming chamber would be lifted above the ground, and the concrete would be squeezed out through the side gaps between the side walls and the ground. Thus, each machine was limited to a maximum kerb height, dependent on the design of that particular machine.

The kerb forming machine of this invention is provided with detachable side walls or skirts 17 to enable the machine 10 to accommodate a mould 15A having a height greater than the standard design height. Typically, the skirts 17 are flat metal sheets which are bolted to the inside of the left and right walls of the hopper 11 and extend from the hopper to the ground. Preferably, the skirts 17 are adjustably mounted to the hopper 11 to accommodate moulds 15A of different height.

The skirts 17 ensure that when higher than standard moulds 15A are used, there are no side gaps between the hopper 11 and the ground, thereby retaining concrete within the ramming chamber for extrusion through the mould 15A.

If required, the pusher plate 13 can be provided with an extension plate, connected thereto, for extending the depth of the pusher plate when higher moulds are used.

The machine 10 has steerable wheels 21 rotatably mounted on respective wheel mounts. The machine 10 is typically provided with a handle 20 for steering the wheels 21. This enables the machine 10 to track a curved path and form concrete kerbing of curved configuration. Each wheel mount has a respective steering arm 22. The handle is connected to one steering arm 22, and the two steering arms are connected by a

steering link 23. The steering link 23 is provided with threaded ends which are each threaded into a socket in a respective end fitting 39. The end fittings 39 are pivotally connected to respective steering arms 22, typically by ball-and-socket mountings.

In conventional machines, both threaded ends of the steering link 23 have the same thread. Thus, when adjustment of the length of the steering link 23 was required, it was necessary to remove the steering link 23 (and its associated end fittings) from the machine.

The steering link 23 of the illustrated embodiment is provided with threaded ends which have opposite threads, i.e. left hand and right hand threads, respectively. This allows for adjustment of the spacing of the wheels 21 while the steering link 23 remains in place on the machine. The locking nut 25 is first loosened, and the steering link 23 is rotated, either clockwise or anticlockwise as appropriate, in order to lengthen or shorten the overall length of the steering link, and hence the spacing between the steering arms 22. Once the desired spacing has been achieved, the locking nut 25 is simply retightened.

In an alternative arrangement (not shown) , the steering link 23 includes an adjustable turnbuckle. In conventional machines, the push rod 29 is a solid rod, of fixed length. Since the length of the push rod 29 cannot be adjusted, wear and tear cannot be compensated for. The machine 10 shown in the illustrated embodiment has an adjustable rod 29, similar to the adjustable steering link 23. The threaded ends of the push rod 29 have left and right handed threads, respectively. The distance between the pusher plate 13 and the crank arm 28 can be adjusted accurately while the push rod 29 remains in place, to accommodate wear and tear.

Each wheel mount is located at the bottom end of a respective wheel strut which is in the form of a telescoping leg having a post 30 εlidable and rotatable

within a sleeve 31. Although each sleeve 31 is fixed relative to the machine, each post 30 may rotate within its respective sleeve 31 to allow the wheels 21 to turn. When forming kerbing of straight line configuration, or of constant curvature, it is necessary to keep the steering handle 20 at a fixed orientation. In conventional machines, the operator is required to manually hold the handle steady at the fixed orientation. This is very difficult to achieve while the machine is in operation and moving.

The machine of the illustrated embodiment is provided with a positive locking mechanism to maintain the wheels in a fixed orientation. As shown in Fig. 1, the locking mechanism may suitably comprise a threaded "T" fitting 33 which is threaded into an opening in the sleeve 31. By screwing the T fitting into the sleeve 31 to engage the post 30, the T fitting 33 prevents relative rotation between the post 30 and sleeve 31, thereby maintaining the respective wheel 21 in a fixed orientation relative to the machine. This eliminates human error in steering, and allows the kerbing to be formed in uniform curves and straight lines.

The wheel struts are mounted to a rail 35 which is slidably adjustable relative to the body 36 of the machine. In this manner, the steering and wheel assembly can be located fully to the left or right of the body 36 of the machine, enabling the machine to pass closely alongside vertical obstacles such as walls. This enables kerbing to be formed close to such vertical obstacles. The machine 10 further comprises three locking

"T" fittings 37 threaded into respective openings in rail 35. The threaded T fittings 37 are located at either end of rail 35 and in the middle thereof. Once the rail 35 has been located at the desired position relative to the body 36 of the machine, the appropriate "T" fitting is threaded through rail 35 into the body 36, to lock the body 36 in position relative to rail 35.

The height of each strut, and hence the height

of the machine, can be varied by adjustment of the relative axial positioning of the post 30 and sleeve 31, using respective height adjustment handles 32. In conventional machines, the handles 32 are permanently in a horizontal orientation. Thus, when the handles 32 were rotated, they pass outside the lateral boundaries of the machine. If the machine is alongside a vertical obstacle such as a wall, the nearmost handle 32 cannot be rotated to adjust the height of the machine. The machine shown in the illustrated embodiment has pivotally mounted handles 32 which can be moved from a normal horizontal orientation to an upright orientation. In its upright configuration, each handle 32 can still be rotated to adjust the height of the machine without being impeded by an adjacent wall or other obstacle.

The pusher assembly in the kerb forming machine described in Australian patent no. 620031 had a unitary pusher plate extending from its upper hinged mounting to its bottom edge. The machine 10 of the preferred embodiment has a removable pusher plate 13 which is secured to the remainder of the pusher assembly 13A by one or more locking "T" nuts 38. This allows the pusher plate 13 to be removed, quickly and easily, from the remainder of the pusher assembly 13A, e.g. for cleaning and/or replacement.

The foregoing describes only one embodiment of this invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention as defined in the following claims.