FIELD OF THE INVENTION

The invention relates to a bolt arrangement for a railway sleeper and to the installation of a railway sleeper using said bolt.

BACKGROUND OF THE INVENTION

As discussed in South African Patent 2005/07217, at a turnout, single railway lines are split into two. At a crossing a facility is provided whereby two lines cross each other. Due to the varying effective width over which the railway lines extend a need exists for railway sleepers of variable lengths.

In a new turnout or crossing it is possible to prefabricate sleepers to the appropriate lengths. At an existing turnout which is to be refurbished it is necessary to fabricate sleepers to replace existing sleepers taking into account the geometrical requirements of the existing installation.

As concrete sleepers are manufactured using moulds of precise dimensions under factory conditions it is not always economically feasible to cast a concrete sleeper, using customary techniques, to produce a product which can be substituted for an existing sleeper in an installed location.

SUMMARY OF INVENTION

The invention provides a railway line fastener which includes an internally threaded metallic sleeve with an open mouth and an apertured first head, and a shank which is threaded over one end and which is threadedly engageable with the metallic sleeve and which has a second head, and a collar bush sized and dimensioned to fit over the shank and having an inner diameter greater than the outer diameter of the threads, the collar bush outer diameter snugly fitting within a hole into which the fastener will be inserted.

The bush may be a nylon sleeve with a washer like portion sized and dimensioned complementarily to the second head of the shank.

The apertured first head aperture may be sized and dimensioned to permit the shaft which is engageable with the metallic sleeve to project thereinto or therethrough. The apertured first head may be a tube nut.

The bush may be an insulating sleeve which is engaged with the shank. The bush may have a plurality of friction enhancing formations on an outer surface thereof.

The second head may be in the form of a nut.

The invention extends to a method of installing a railway sleeper which includes the steps of marking an elongate cast cementitious member at a plurality of locations, forming a plurality of holes through the member, each hole being at a respective location, placing at least a shank of a railway line fastener over which a collar has been located into each respective hole, positioning the member below a railway line and engaging an internally threaded metallic sleeve with an open mouth and an apertured first head with a threaded portion of the shank thereby to secure the railway line to the member.

The member may be marked at the plurality of locations by placing the member in a position, below the railway line, at which the member is to be secured to the railway line.

The positions of the holes, which are formed in the member, may be determined by reference to holes in at least one base plate to which the railway line is attached.

By using the method of the invention the base plate is attached to the sleeper and the railway line, which is secured to the base plate, is thereby attached to the sleeper.

The holes in the member may be formed by drilling the member in situ.

Each hole may be drilled from what in use is an upper side of the member to what in use is a lower side of the member.

The railway line fastener may be as described above.

The second head may be a nut mounted in an insulating holder such as a plastics sleeve or cup or the like which is frictional ly or adhesively secured to the member.

In a variation of the invention the railway fastener may be used from the bottom i.e. in opposite orientation to that described directly above. BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 shows a fastener for use in the invention; and

Figure 2 illustrates the use of the fastener shown in Figure 1.

The dimensions shown on the drawing are by way of illustration only and not intended to limit the scope of the invention and different dimensions will apply in different circumstances.

DESCRIPTION OF PREFERRED EMBODIMENT

Figure 1 shows a fastener 10 with a first element 12 which comprises an internally threaded metallic sleeve 12 with an open mouth 16 and a hexagonal head 18 having an outwardly directed aperture opening 19, and a second element 20 which comprises a shank 22 which is threaded over one end 24 and which has a hexagonal head 26. Washers 23 are also shown which are used in the usual way. Figure 2 shows the use of the fastener of Figure 1 including a bolt 21 which comprises the shank 22 which is threaded 24 and which has the hexagonal head 26. A collar bush 28 of a suitable plastics material, such as Nylon-66, is engaged with the shank 22, abuts the head 26 and, when installed, acts on an upper surface of a concrete sleeper member 32, via a base plate 34. Between the head 26 and the base plate 34 are located a top washer 36 which abuts a flange portion of the bush 28 and a bottom washer 38 which is compressed in use between the flange portion of the bush 28 and the base plate 34. A rubber or HDPE pad 40, or another resiliently deformable material, is placed between the base plate 34 and the concrete sleeper member 32 to permit sufficient tightening of the fastener and maintenance of same.

In the example shown, a 25 mm diameter hole 42 is cored through the sleeper member 32 so that the threaded shank 22 can pass therethrough. At the opposed end of the hole from where the shank 22 enters is inserted a tube nut 12 of which the head 18 abuts the lower surface of the sleeper member 32 and thus can readily be accessed by a spanner (not shown). The internally threaded portion of the tube nut 12 has a thread engagement 44 of 55 mm in the embodiment shown.

When in use, a plurality of fasteners 10 are used and the bolts thereof are turned to be secured and tightened so that they are firmly engaged with the nuts and the base plates are thereby secured in position. The railway lines which at all times remain secured to the base plates are thereby secured to the member.

The collar bush which is in the form of an insulating sleeve 28, in the case of the embodiment shown made of Nylon-66, prevents direct metal-to-metal contact between the head 26 and the shank 22 on the one hand, and the base plate on the other hand. This preserves the integrity of communication signals which are propagated through wheels and other structure of tracked vehicles on the railway lines. Friction enhancing formations such as splines or knurling 27 may be provided on the sleeve 14, and protrusions 17 on an inner surface of the head 18, to help the sleeve engage with the concrete sleeper so that, as the shank is tightened, there is a reduced tendency of the element 12 to rotate.

It is believed to be an advantage of the invention that the shaft of the bolt may be of a relatively smaller diameter thereby using less steel or other tensile metal or material. In addition, the length of the shank and depth of thread engagement may be selected as required for the load.