BACKGROUND OF THE INVENTION One way in which concrete sleepers are produced is using steel cast shoulders. The steel shoulders are embedded into the concrete sleeper and are used to attach the concrete sleeper to railway rails via clips.

This works very effectively.

Traditional shoulders, such as those shown in US Patent Nos. 4466569 and 4934594, all have holes in which a clip is located therethrough to connect the railway rail to the sleeper. During production, various mechanisms have been developed to hold the shoulder via the hole so that the steel shoulders are positioned a precise distance from each other within the concrete sleeper. Such mechanisms commonly incorporate a simple pin that engages the hole within the shoulder to achieve the desired spacing of the shoulders.

One disadvantage with traditional shoulders is that the other elements that are used in conjunction with the sleeperto hold the railway rail, such as clips and shock absorption pads, must be transported to the site separate to the concrete sleeper. Therefore, if there are not sufficient clips or pads, due to the clips or pads being lost or due to poor management, then production of the railway line is delayed.

To address this difficulty, pre-staged shoulders have been developed such as the shoulders disclosed in International patent application

No. PCT/GB92/02357 (WO 96/27708). These pre-staged shoulders have the advantage that once the shoulders are located within the sleeper the additional elements, such as the clips and pads, can be fitted to the shoulder and transported with the sleepers. Hence, there are no problems with having an equal number of sleepers, clips and pads as is required with traditional shoulders.

However, production of concrete sleepers, incorporating pre- staged shoulders, has been limited due-to difficulties in production.

Production methods used for traditional shoulders are unable to be used for pre-staged shoulders as there are no holes located within pre-staged shoulders to hold the shoulders in a desired position.

One production method for concrete sleepers that uses pre- staged sleepers incorporates the use of polyurethane moulding that are fixed to a sleeper mould. The pre-staged shoulders are manually pushed into the polyurethane moulding to hold the shoulders in a desired position when concrete is poured into the mould.

One disadvantage with using polyurethane moulding is the high reliance upon the people who locate the pre-staged shoulders within the moulding. The pre-staged shoulders can often be seated incorrectly and in such instances the completed concrete sleeper cannot be used and must be discarded. Further, the polyurethane moulding can interfere with demoulding causing the concrete sleeper to crack. Again, in this instance, the concrete sleeper must be discarded. Still further, there are high capital costs and high maintenance costs in maintaining the accuracy and reliability of the moulding.

Other methods, similar to that described above, have been developed. One production method utilises springs and steel balls to increase the engagement and holding of the shoulder. Another method incorporates the use of a spring-loaded latch to hold the shoulders.

However, the problems discussed above, still exist.

OBJECT OF THE INVENTION It is an object of the invention to overcome or alleviate the

above disadvantages or provide the consumer with a useful or commercial choice.

SUMMARY OF THE INVENTION In one form, although not necessarily the broadest or only form, the invention resides in an apparatus for manufacturing sleepers, the apparatus comprising: a mould for location of a settable material, said mould including a base having at least a pair of holes for location of two cast-in components; an engagement mechanism to engage said components that are located within the holes ; and a spacer located between the cast-in components to space the cast-in components at a predetermine distance from each other; wherein the engagement mechanism exerts a longitudinal force and a normal force with respect to the base on said cast-in components to hold the cast-in components in a predetermined position within the mould.

The cast-in components may be shoulders. Normally, the shoulders are pre-staged shoulders.

The settable material is usually concrete. However, other settable materials such as composites, rubber and polyurethane's may be used.

The holes may be sized so that there is clearance between the holes and the shoulders during demoulding. Preferably, there is clearance between at least the front and back sides of the holes.

The engagement mechanism may include a pair of engagement members. Each engagement member may be a spring.

Preferably, each engagement member is a leaf spring.

The pair of engagement members may be rotatable.

Preferably, each engagement member is mounted to a separate shaft. An actuator may rotate the shafts. The actuator may incorporate a push-pin attached to a cam.

The spacer is preferably a gauging plate. Preferably, the gauging plate is attached to the actuator. More preferably, the gauging plate

is attached to the push-pin.

Preferably, the gauging plate and engagement members are moved simultaneously.

Usually, a leading edge of the gauging plate is shaped to allow the plate to slide against the pair of pre-staged shoulders. Preferably, the leading edge of the plate is bevelled at its corners.

In another form, the invention resides in a method for manufacturing sleepers, the method comprising the steps of: locating a pair of cast-in components within a pair of holes located within a base of a mould ; engaging the cast-in components using an engagement mechanism to exert a longitudinal force and a normal force on said cast-in components to hold the shoulders in a predetermined position within the mould ; spacing the cast-in components using a spacing means a predetermined distance from each other; and pouring settable material into the mould.

The method of manufacturing the sleepers may include the additional step of demoulding the sleeper from the mould so that the cast-in components do not rub against the mould.

Preferably, the engaging and spacing of the cast-in components occurs simultaneously.

In another embodiment, the invention resides in a sleeper made by the above method and/or apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention, by way of example only, will be described with reference to the accompanying drawings in which: FIG. 1 is a perspective view of an underside of an apparatus to manufacture concrete sleepers according to an embodiment of the invention; FIG. 2 is a side cross-sectional view of the apparatus for manufacturing concrete sleeper according to FIG. 1; FIG. 3 is a top view of the apparatus for manufacturing

concrete sleepers according to FIG. 1; FIG. 4 is a top view of an engagement mechanism according to an embodiment of the invention; FIG. 5 is a side view of the engagement mechanism according to FIG. 4; FIG. 6 is an end view of the apparatus for manufacturing concrete sleepers in an unlocked position; FIG. 7 is an end view of the apparatus for manufacturing concrete sleepers in a first position; FIG. 8 is an end view of the apparatus for manufacturing concrete sleepers in a locked position; and FIG. 9 is a perspective view of a sleeper constructed using the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An apparatus 10 for manufacturing concrete sleepers is shown in FIG. 1, FIG. 2 and FIG. 3 comprising four concrete moulds 100 and two engagement mechanisms 200. The concrete sleeper 11 that isproduced is shown in FIG. 9.

Each mould 100 is made of standard material, such as iron, and is used to produce a single concrete sleeper. A pair of holes 110 and 111 are located at each end of each mould. An engagement mechanism 200 is located below the holes 110 and 111 at each end of the mould 100.

Each hole 110 and 111 is sized so that a pre-staged shoulder 300 can be easily located within the holes 110 and 111 with substantial clearance at the front side 112 and back side 113 of each of the holes.

The engagement mechanism 200 includes a push-pin 210 that is attached to a base 101 of the mould 100 by attachment plates 220. The push-pin 210 is able to be reciprocated with respect to the attachment plates 220. Further details of the push-pin 210 are shown in FIG. 4 and FIG. 5.

Two shafts 230, located on opposite sides of the push-pin 210, extend through the attachment plates 220. The two shafts 230 are rotatable with respect to the attachment plates 220.

Two cams 240 are attached to the push-pin 210. Each cam 240 has a slot 241 in which is located a lever 250. Each lever 250 is attached to a different shaft 230. Reciprocation of the push-pin causes the levers 250 to move within the cams 240 to further cause the shafts 230 to be rotated.

Four leaf springs 260 are attached to and spaced along the length of each of the shafts 230. The leaf springs 260 are attached to the shafts using nuts and bolts 262.

Each leaf spring 260 is curved adjacent an end to allow engagement of the leaf spring with a recess located within a pre-staged shoulder 300.

Four gauging plates 270 are attached to the push-pin 210 between the push-pin 210 and the moulds 100. The gauging plates 270 are arranged such that movement of the push-pin 210 causes the gauging plates 270 to cover a portion of the pairs of holes 110 and 111. The gauging plates 270 are substantially rectangular in shape with corners 271 of the leading edge 272 being bevelled.

A concrete sleeper is produced using the apparatus by manually inserting pre-staged shoulders 300 in the holes 110 and 111 in the mould 100 as shown in FIG. 6. The pre-staged shoulders 300 are easily located with the holes 110 and 111 due to the clearance provided by the holes 110 and 111.

The push-pin 200 is then moved causing the slots 241 located within cams 240 to act upon the respective levers 250. The levers 250 then causes rotation of the shafts 230 and leaf springs 260.

The gauging plates 270 are also moved by the push-pin 210 to position between the gauging plate 270 and respective pairs of pre-stagged shoulders 300 and over a portion of the holes 110 and 111. The gauging plates 270 are dimensioned and located between the pre-staged shoulders 300 so as to correlate with the required final cast position of the pre-staged shoulders 300 with respect to the desired rail gauge and rail width.

As the leaf springs 260 are rotated, they contact respective pre-

staged shoulders 300 as shown in FIG. 7. At the point of contact between each leaf spring 270 and the pre-staged shoulder 300, the direction of the force is mainly horizontal causing the pre-staged shoulder 300 to slide horizontally within the hole 110. As the shaft 230 continues to rotate, pre- stagged shoulder 300 moves until it abuts against the gauging plate 270.

The gauging plate 270 has a two-point contact with the pre-stagged shoulder 300 whilst the leaf spring 260 has a single point of contact with pre-staged shoulder 300. This creates a self-aligning effect for the pre-staged shoulder 300.

The holes 110 and 111 are sized so that the base 101 of the mould 100 that extends with the mould 100 between two adjacent pre-staged shoulders 300 is of a smaller spacing than that provided by the gauging plate 270. Hence a gap 280 is created between the base 101 of the mould 100 and the pre-staged shoulder 300.

As the shaft 230 continues to rotate, the direction of the leaf spring 260 force changes from horizontal to vertical. This change in force direction is created by the arc of rotation of the leaf spring 260, and the dimension strain of the leaf spring 260 bends and is pulled downward by the shaft. The bending strength of the leaf spring 260 is selected to provide a balance between strong horizontal push force and a slow rate of build up of vertical holding force. The cam 240 is designed so that the leaf spring 260 remains engaged without the need to continually apply force to the push-pin 210. The pre-staged shoulder 300 is held in position via a downward vertical force creating a friction resistance to movement as shown in FIG. 8.

Concrete is then placed within the mould 100. As the pre- staged shoulders 300 are held tightly to the base 101 of the mould 100, there is little or no leakage of concrete through the respective holes 110 and 111.

Once the concrete has set, the leaf springs 260 are disengaged from the pre-staged shoulders 300 by moving the push-pin 210 in the opposite direction and sequence of operation for the engagement mechanism 200 is reversed.

Concrete sleepers can then be removed from their respective

moulds 100. As the holes 110 and 111 provide sufficient clearance and there is a gap 280 located between each pre-staged shoulder 300 and the base 101 of the mould 100, no unwanted force is generated from the pre- staged shoulder 300 rubbing against the mould 100 during demoulding.

Therefore, the likelihood of stress cracks being formed through the concrete sleeper during demoulding is eliminated.

The apparatus for manufacturing concrete mould 100 is relatively inexpensive to produce. An unskilled person can locate the pre- stagged shoulders 300 within the holes 110 and 111 in the mould 100 as the engagement mechanism ensures that the pre-staged shoulders 300 are located in their desired position regardless of their initial placement within the holes 110 and 111.

It should be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit or scope of the invention.