Railways: surface track – Rail seats – Cushions
Patent
1995-11-02
1997-12-02
Morano, S. Joseph
Railways: surface track
Rail seats
Cushions
238107, 238351, E01B 968
Patent
active
056926774
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for supporting and wedging a railway rail on a tie.
Devices of this type comprise, in particular, a resilient pad on which the base of the rail rests, and insulating tabs interposed between the rail and spring clips which are fixed on inserts secured laterally in the tie.
In such devices, the pad is generally of uniform thickness while the tabs bear against the flange of the rail without their bottom edges coming into contact with the pad.
In that configuration, the bottom edge of a tab remains at a level above the base of the rail. It frequently happens that during one of the stages of track-laying, it is necessary to lift up the rail and replace the pads under the rail at regular intervals with steel support rollers of a diameter greater than the thickness of the pad in order to provide the rail with a degree of freedom in translation. The purpose of this operation is to make stresses uniform over the entire rail.
Unfortunately it is very difficult to remove pads of uniform thickness because of their lack of flexibility.
In addition, the shape and the position of the tabs are unsuitable for obtaining good resistance to compression under the action of lateral forces generated by rolling stock and transmitted by the rail.
OBJECTS OF THE INVENTION
An object of the present invention is to solve those problems in satisfactory manner.
This object is achieved by means of a device in which the pad comprises a central portion supporting the base of the rail and two symmetrical lateral portions of smaller thickness disposed beneath the bottom edges of the tabs which are themselves situated at a level lower than the base of the rail.
SUMMARY OF THE INVENTION
According to an advantageous characteristic, there is clearance between the bottom edges of the tabs and the corresponding lateral portions of the pad.
According to another characteristic, the clearance between the bottom edges of the tabs and the lateral portions of the pad lies in the range 0.5 mm to 5 mm.
According to yet another characteristic, the difference in thickness between the central portion and the lateral portions of the pad is not less than 3 mm when the rail is in place, and in a variant embodiment, the thickness of the lateral portions of the pad is not greater than half the thickness of the central portion.
In a particular embodiment, the position of the bottom edge of each tab is situated at least 2 mm below the level of the base of the rail, and is preferably constituted by a substantially horizontal plane face.
According to other characteristics, for the purpose of wedging the pad, its lateral portions are engaged between corresponding shoulders formed on the top face of the tie.
In the latter variant, said lateral portions are of a length that is shorter than the length of the central portion.
In addition, said lateral portions of the pad are solid whereas the central portion includes hollowed-out zones.
The device of the invention makes it easy to remove the pad from its location beneath the length of rail by lifting the lateral portions through 90.degree. and by exerting a traction force parallel to said length.
In the same manner, installing said pad is facilitated by the flexibility of the lateral portions.
The combination between the pad and the tabs as described above also makes it possible to obtain resistance to compression that is satisfactory insofar as the bottom face of the rail is situated above the bottom edges of the tabs, thereby enabling a better distribution of stresses in the tab and therefore better resistance than in the case of prior devices.
The present invention will be better understood on reading the following description accompanied by a drawing in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section view through the device of the invention associated with the rail fixing system; and
FIG. 2 is a perspective view of one embodiment of the pad of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The device shown in FI
REFERENCES:
patent: 3581990 (1971-06-01), Kirik
patent: 3784098 (1974-01-01), Serafin et al.
patent: 4216904 (1980-08-01), Vivion
patent: 4648554 (1987-03-01), McQueen
patent: 4771944 (1988-09-01), Brister et al.
patent: 5016816 (1991-05-01), Lanham
Allevard
Morano S. Joseph
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