Railways: surface track – Fastenings – Clamps
Patent
1990-04-06
1991-12-03
Spar, Robert J.
Railways: surface track
Fastenings
Clamps
238338, E01B 940
Patent
active
050693867
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a clip for fastening the rails of a railway on their sleepers, comprising displacement stopping means and spring, and in particular to an improvement in or relating to the systems described in French Patents Nos. 2 256 287 and 2 330 803.
As is known, the rails rest on sleepers or ties (made of wood, concrete or metal), on slabs, or on metal or plastic parts known as "base plates", which base plates rest on sleepers or slabs. In the following description, the word "support" will be used to designate these sleepers, base plates or slabs. Between the lower base flange of rail and the support is intercalated a so-called sole plate, generally made of rubber. Its role is to constitute an elastic shock absorber allowing the rail to move slightly with respect to its support, thus avoiding ruin of the support under the effect of the shocks and efforts generated by the rolling stock. In order to conserve the geometry of the railway, despite the various efforts induced in the rail and the slight movements thereof, means for clamping the rail on its support must obviously be provided. These clamping means generally abut on the edge of the base flange and are anchored in the supports. At the present time and taking into account the use under the rail of elastic soles, these rail clamping means are also elastic so as to conserve as much as possible their effort of clamping on the rail despite the slight movements of the latter or the possible relaxations of the anchorings of these clamping means in the supports. In the following description, the clamping means and their anchorings will be collectively referred to as rail clips.
There are several families of rail clips, in particular screwed and non-screwed clips. Among the non-screwed clips, there is a large number of different designs. One of the most recent and most wide-spread non-screwed designs is the one disclosed in French Patents Nos. 2 256 287 and 2 330 803.
However, this design presents a relatively major drawback that the present invention intends to eliminate. Beforehand, the functioning of a rail clip according to French Patents 2 256 287 and 2 330 803 should briefly be recalled. To that end, the description and numbering of Patent 2 256 287 will be employed.
Such a clip is shown in clamped position in FIG. 9 of said Patent. This clip comprises a spring (according to FIGS. 1 to 3 or 4 to 6) and an anchoring means 10 fast with the support 6. To place it in this position, section 1 of the spring must be introduced (by lateral translation with respect to the rail) into the hole 10C of the anchoring means 10. During such introduction, section 3 of the spring is obliged to rise along ramp 10A and the spring is thus deformed; this causes an effort of clamping by section 5 on the rail 8 (an insulating insert 9 simply enabling contact between the spring and the rail to be avoided).
The behaviour of the rail and firstly the stresses to which it is subjected will now be examined.
These stresses are mainly of two orders:
It is the action of the wheels which must be examined in greater detail:
During their passage, the wheels exert an oblique effort on the rail head, which effort may be broken down into a vertical effort directed downwardly and perpendicular to the rail and a lateral effort directed towards the outside of the track and contained in a plane perpendicular to the rail The rail therefore tends to rotate on itself, about its own longitudinal axis. During passage of an axle, and especially in a curve, the two lines of rail of the same railway track thus rotate but in opposite directions from each other, which causes a localized widening of the gauge of the track. Such widening of the gauge may become critical in curves of small radius or when the cant given to the curved track is very different from the theoretical one which would correspond to the speed of the vehicle. This phenomenon is also accentuated by certain designs of rolling stock which present an effort of curvetaking of the vehicle greater than others. In a curve
REFERENCES:
patent: 3297253 (1967-01-01), Astley et al.
patent: 4190200 (1980-02-01), Morrow
patent: 4413777 (1983-11-01), Brown
Allevard Industries
Eller J.
Nawrocki Lawrence M.
Spar Robert J.
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