Railways: surface track – Fastenings
Patent
1981-02-10
1984-08-07
Peters, Jr., Joseph F.
Railways: surface track
Fastenings
238349, 238351, E01B 930
Patent
active
044638981
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an improvement in elastic rail fasteners particularly those which use a rail clip and a clip holder. The purpose of the clip holder is to secure the rail clip to a rail sleeper and enables the rail clip to bear down on the rail flange.
Numerous elastic rail fastening systems of this type have been devised. Any rail fastening system must be able to maintain the rail in position under the normal stress conditions arising from use of the rails and from environmental stresses particularly thermal stresses. Modern rail systems are adopting welded rails and thermal stresses are a predominant factor in welded rails. It has been observed that a major long term difficulty with rails is the tendency of the rails to move in the predominant direction of travel for trains on the rail track. This tendency is called rail creep and it is most important that any elastic rail fastening systems not only prevent lateral rail movement but also prevent axial movement or rail creep.
Past attempts to reduce rail creep have concentrated on increasing the hold down force of the rail clip on the rail flange or on increasing the frictional resistance between the rail, the sleeper and the clip by, for example, carefully selecting material to be used as rail pads between the rail and the sleeper.
It is an object of this invention to reduce rail creep as compared to conventional elastic fastening systems.
To this end the present invention provides a locking element for use with a rail fastening system comprising an elastic rail clip, a clip holder adapted to hold the clip in position on the flange of the rail. The locking element is adapted to lie between the rail flange and the rail clip holder, and the locking element is held down onto the rail flange by the rail clip, and the clip holder interfits with the locking element such that any movement of the locking element in a direction parallel to the rail axis is at least partially translated into a lateral pressure of the locking element against the rail.
Ideally a portion of the abutting surfaces of the locking element and the clip holder are inclined to the axis of the rail so that any movement of the locking element parallel to the rail results in the locking element being wedged inwardly against the rail, thereby increasing contact pressure on the rail from a horizontal lateral direction. Prior art fastening systems only applied a vertical hold down force to the rail flange. The present invention however is able to apply both a vertical and horizontal force to the rail and this additionally restrains rail creep. Either locking element or the clipholder includes a U shaped recess into which the other part interfits and either the corners of said U have a radius of curvature of at least 6 mm or the sides of said U are inclined to the base of said U at an angle of at least 100.degree..
The locking element of this invention ideally doubles as an insulator between the rail clip and the rail flange. In the prior art insulators of this kind have been described for example in U.S. Pat. Nos. 3,610,526 to Burwell (see FIG. 4), 3,460,756 to Sanson, 3,463,394 to Jones et al. None of the insulators described in these patents or insulators used in practice in the prior art functioned as locking elements. The interaction of the surface of the insulator against the clip holder in the prior art did not result in longitudinal movement of the insulator being translated into lateral pressure on the edge of the rail foot. In each of the prior art insulators, the insulators and their associated rail clip holders are not shaped to provide a wedge like interfitting. Rather the angles at the corners of the rail clip holders and internal corners of the insulators adjacent the clip holders are effectively right angles.
From the above it can be seen that the locking element of the invention must be shaped to lie on top of the rail flange and on the shoulder or side of the rail flange so that it lies between the rail clip and the top surface of the rail flange and lies between the cli
REFERENCES:
patent: 3297253 (1967-01-01), Astley et al.
patent: 3460756 (1969-08-01), Sanson
patent: 3463394 (1969-08-01), Jones et al.
patent: 3610526 (1971-10-01), Burwell
patent: 4104483 (1978-08-01), Seeley
patent: 4274582 (1981-06-01), Fee
patent: 4284238 (1981-08-01), Veroef
patent: 4313563 (1982-02-01), Young
Remes Wally A.
Young Hartley F.
Hill Mitchell J.
Peters Jr. Joseph F.
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