Railways: surface track – Tie arrangement
Reexamination Certificate
1998-08-21
2001-04-17
Stormer, Russell D. (Department: 3617)
Railways: surface track
Tie arrangement
C238S029000, C238S062000
Reexamination Certificate
active
06216958
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a railway track comprising a ballast bed, sleepers disposed on the ballast bed and rails mounted on the sleepers. The invention further relates to a sleeper for such a railway track as well as a gap cover for covering the gap between such sleepers.
Sleeper according to the state of the art, may be manufactured of wood. Concrete or steel, concrete sleepers of the German type B70 are at present most frequently installed, the axial spacing of the sleepers being 60 cm with a maximum sleeper width of 30 cm.
This track system, conceived to be durable, is exposed to all sorts of weather conditions and requires constant maintenance. The very high maintenance costs include lifting, tamping and realigning the track in the event of positional shifts, cleaning the track in the event of severe soiling and eradication of plant growth in the ballast bed.
SUMMARY OF THE INVENTION
It is the object of the invention to so further develop a railway track of the type mentioned in the opening paragraph that the upkeep costs may be minimized and investments in respect of earthwork may be reduced.
The object is essentially attained in that adjoining sleepers are disposed in a longitudinal direction of the track closely adjoining one another but without mutual contact, leaving a gap therebetween. At least one drainage channel extends transversely to the longitudinal direction of the track which is assigned to each sleeper for lateral water drainage.
These expedients entail multiple advantages.
Due to the enlargement of the support surface of the sleepers on the ballast, the surface pressure onto the ballast is reduced. Because of the increase of the inherent weight of the sleeper and the enlargement of the front surfaces, i.e. the end faces of the sleepers, the resistance to transverse displacement is increased. By draining the surface water via the drainage channel at least a major part of the surface water is kept away from the load-bearing substructure.
Because of the lower surface pressure, the higher resistance to transverse displacement and the drainage of surface water, the positional stability of the track is increased considerably. This entails at the same time load reduction for the substructure, i.e. the necessary investments in earthwork are minimized.
By reducing loads on the ballast and thus likewise the substructure and by reducing the penetration of surface water into the track grid the surface water is on the one hand to a large extent kept away from the load-bearing substructure underneath the ballast bed, thus making it possible to avoid or reduce a softening of the substructure and thus a destabilization of the entire track. Furthermore plant growth in the ballast bed is practically entirely prevented due to the ballast bed being covered completely or at least almost completely by the sleepers and the side-way drainage of the surface water so that in these regards expensive maintenance operations for the cross-section covered by the sleepers may be dispensed with. In addition, the safety-related requirements are met so that in the outer regions of the sleeper (shoulder) only a considerably simplified vegetation care is still necessary. Soiling of the ballast bed is likewise practically entirely excluded and the expensive cleaning of the ballast bed may thus likewise be dispensed with.
The size of the gap provided for between adjoining sleepers is so selected that radial laying of the sleepers in the region of curves in the section is possible, preferably without the sleepers touching one another in these regions.
The drainage channels may in principle be designed horizontally, that is to say parallel to the longitudinal axis of the sleepers; a more reliable and quicker drainage is, however, ensured if the drainage channels according to a further feature of the invention are designed inclined in the longitudinal direction of the sleepers. If the transverse inclination of the drainage channels is greater than the maximum superelevation of the track in the region of curves, the water, even in the region of superelevations, may always be drained reliably towards the outside, that is to say in two-tracked sections towards the field side.
It is particularly advantageous if the drainage channels comprise two sections inclined in opposite directions for lateral water drainage in the direction towards both sleeper heads, in which context the transverse inclination of the drainage channels may in this case be particularly strong with the result that even in the event of considerable track superelevations a reliable drainage is possible. In addition, the sleepers may then be designed symmetrically.
In a preferred embodiment of the invention, the upper sides of the sleepers are at least partly designed to be inclined in the longitudinal direction of the track, that is to say towards the drainage channels. This ensures a rapid and reliable drainage and the permanent deposition of dirt on the sleeper is simultaneously drastically reduced as the sleepers are rinsed clean after heavy rainfalls and the dirt is discharged sideways via the drainage channels.
In order to prevent water from penetrating the ballast bed via the gap between the sleepers, a gap cover is provided according to a further important aspect of the invention. This gap cover may comprise a covering element bearing on adjoining sleepers at both ends of the gap and may in the simplest case be designed as a cover plate, for example even a concrete panel. The gap cover may, however, also be fitted in form-fitting and/or press-fitting engagement and, where appropriate, be adhesively bonded into in the gap or in the region of the gap. The gap cover may consist of a suitable plastics material, of rubber or rubber-like material or it might be formed of foaming material similar to canned foam or it might also be in the form of an elastically compressible strip of suitable synthetic resin which is fitted into the gap. It is important for the gap cover to be able to seal gaps of different width or gaps of changing width, as in the region of curves in the track the sleepers are laid radially and the width of the gaps thus varies from one sleeper face to the other.
In cross-section the gap cover preferably comprises a roof section covering the gap as well as a section of the sleepers bordering thereon, wide enough to reliably cover the gap even if the maximum gap width occurs. The gap cover may furthermore comprise a foot section projecting downwardly into the gap, which may be narrower than the minimum gap width occurring and which prevents a lateral sliding of the gap cover. Advantageously this foot section in the gap is fitted in press-fitting or form-fitting relationship. This may in particular be attained in that at the foot section holding means are provided which adapt to the respective gap width and which are preferably elastically deformable and which may be designed in particular as expansion elements extending transversely to the gap. After laying the sleepers these holding means are pressed into the gap until the roof section comes to rest on the sleepers, in which case the expansion elements are bent or folded upwardly to a greater or lesser extent, thus anchoring themselves in the gap.
If designed appropriately, the gap cover may perform as a fluid-tight seal.
Each sleeper may be provided with one or more drainage channels in order to drain the surface water of any sleeper sideways. In a preferred embodiment of the invention, however, a joint drainage channel is assigned to any two adjoining sleepers. This may for example be attained in that between adjoining sleepers a gutter is provided, the adjoining sleepers being able to cover the gutter from both sides.
In a particularly preferred further development of the invention provision is made, however, that adjoining sleepers overlap in longitudinal direction of the track without mutual contact and that the drainage channel in the region of overlap is preferably designed to form an integral part of one of the two adjoining sleep
Jules Frantz F.
Rabin & Champagne PC
Stormer Russell D.
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