RAIL SUPPORT WITH PROVISION FOR BALLAST

Abstract: A novel railroad crosstie (1) is disclosed comprising a cavity-reservoir (4) which serves as a container for small grade ballast or pea gravel which is automatically directed underneath the crosstie (1) in proportion to the settlement of the underlying ballast. New small grade ballast or pea gravel is automatically deposited as a result of the combined effects of gravity and the amplitude of vertical oscillation introduced by the wheel sets of passing trains.

Description: Rail Support With Provision For Ball ast Background of the Invention The invention presented herein applies to rail supports such as CROSSTIES and SLAB SECTIONS, the bottom faces of which transmit and distribute dynamic loads into the ballast layer placed between the rail support and the subgrade. The loads are applied to the rails by the wheel sets of moving trains. It is known that these repeated vibrating loads progressively compact the ballast and the subjacent subgrade, thus causing a progressive settlement of the railroad tracks. The amplitude of this settlement being variable locally, it is necessary, for reasons of safety, riding comfort, and the preservation of materials, to periodically reestablish the track elevation and to correct the vertical profile, raising the rail support by an amount proportional to the local settlement, and to consolidate the corrected vertical position by the elimination of the voids created under the raised rail support. This operation, called surfacing, is realized by different methods, one of which is the "packing" to which this invention is related. Packing consists in the introduction, with help of special shovels or injectors, of small grade ballast, or pea gravel, underneath the crossties being worked on, while the said crossties are kept in a raised position at the. desired elevation, by appropriate hoisting equipment such as lifting jacks for example. This method, called "shovel packing", was highly appreciated a few years ago, and it still is today, by various railroads, because the method maintains the equilibrated structure of the ballast moulds which slowly develop under each crosstie; it presents, however, the inconvenience to be time-consuming and expensive, for it cannot be totally mechanized. It is indeed necessary, after having raised the track, to remove the ballast at least on each side of the elevated tie head and at least down to the bottom of the tie, to allow for the introduction by the shovel or the injector of a measured quantity of pea gravel, sized according to the local settlement in such a manner, that after the passage of a certain number of trains, the pea gravel being compacted, the position of the rail support is consolidated at the desired elevation. In view of above mentioned inconvenience, though of purely economical nature, preference has been given to the development and application of the presently fully mechanized method of "tamping", which consists in the "amplification" of the ballast mould, squeezing it under each tie with help of vibrating tamping tools, armed with vertical plates, which are plunged into the space between ties, and closed toward the tie to be tamped. One of the side OMPI effects of tamping is that at each stroke, the equilibrated structure of the ballast mould around the crosstie is destroyed. The tamping operation must generally be completed by a vertical, vibratory compaction operation in order to rebuild a certain compaction and a certain stability of the ballast, at least in the area surrounding the crosstie, before the track is reopened to traffic. It has also been observed that the method of repeated tamping causes the edges of the ballast stones to be rapidly eroded, thus progressively reducing their interlocking quality. Summary of the Invention The invention aims at the application of the method of packing small grade ballast or pea gravel under the rail support in an economical and quasi automatic mode, in order to bring the undisputed technical advantages of this method back into general application. To obtain this objective, the present invention proposes a rail support characterized by the fact that it comprises at least one cavity-reser¬ voir serving as a container of small grade ballast or pea gravel to flow out of the reservoir and to be directed automatically underneath the rail support in proportion to the settlement of the underlaying ballast, under the combined effect of gravity and the amplitude of the vertical oscillations induced by the wheel sets of passing trains. The drawing at the appendix illustrates, as an example, one of the possible forms of the invention: Brief Description of the Drawings Figure 1 is in plain view; figure 2 is the view in elevation of the section A-A through figure 1; figure 3 shows the section H-H of figure 1 in elevation; figure 4 shows the bottom face; figure 5 and 6 show the cross-sections B-B and C-C of fig. 2; figure 7 and 8 show the cross-sections D-D and E-E of fig. 3. Description of the Preferred Embodiments The rail support in this example is a concrete tie (1) with two rails (2) and (3), fastened by common means which are not illustrated. The structure of this concrete tie (1) includes two cavities (4) opening on the surface of said tie (1), placed as close to the rails (2) and (3) as possible without interfering with their means of fastening. The bottom (5) of these two cavities is inclined from the most distant face (6) toward the face closest (7) to the rail. To this face (7) are connected two lateral conduits (8) and (8') . the orientation of which is parallel to that of the longitudinal axis of the tie (1), and the faces of which are biased toward the bottom face (9) with the openings (10) and (10') clearly visible on figure 4. The openings (10) and (10') are centered under the rails (2) and (3) and spaced transversally in such a proportion that the distance between two openings corresponds approximatively to two times the distance which separates them from the lateral faces (11) and (12) of the tie (1). The dimensions of the tie (1) are of course established with regard to the continuity of mechanical resistance through the cavities (4) and their conduits (8) and (8'). In a like manner, the width of the bottom face (9) of the tie (1) is increased by the sum of the widths of the two openings (10) and (10') in order not to exceed the unit surface pressure admitted for a standard concrete tie. The "packing" operation of a railroad track built on crossties such as described above, is extremely simple. It is sufficient to fill the cavities (4) with small grade ballast or pea gravel. As soon as the track settlement becomes irregular, the packing process is initiated automatically by the oscillations induced by the wheel sets in motion, as mentioned before. In fact, as symbolized by the small arrows on figure 6, the particles of the small grade ballast or pea gravel contained in the cavity (4), by their weight have the tendency to flow underneath the bottom face (9) of the crosstie (1) onto the underlaying ballast. This outflow does not happen when the elasticity of the subgrade and ballast allows the latter to follow the vertical oscillations of the loaded rails or, as a matter of fact, as long as there is no permanent settlement, or as long as the settlement takes place over relatively important distances. But as soon as a certain local settlement under a tie is exceeding the one on neighboring ties, a void is created underneath after each passage of a loaded wheel-set, and at that moment, the particles of the small ballast or pea gravel, activated by the oscillations, start flowing and progressively fill the void under then bottom face (9) of the tie; or more to the point, the void is filled while it is created. The effect of automatic filling of the void produced under the rail support is even more profitable nowadays with the wide-spread use of continuous welded rail which is more resistant, elastic, and more homogenuous than before. The rail being less subject to deformation, it bridges the irregular settlement of the underlayin ballast, thus further increasing the amplitude of the vertical oscillations at locations, where the ballast mould has settled more than under neighboring crossties. In the form of realization given as an example, the outflow of small grade ballast or pea gravel is facilitated by the conical shape of the conduits (8) and (8') which, combined with the effect of the vertical oscillations of the tie, accelerates the outflow and hinders the backing or lock-up of the particles in the said conduits; but this particularity is not indispensable. Similarly the transverse symmetrical partitioning of the openings (10) and (10') on the bottom face (9) of the crosstie produces an equal distribution of the particles on either side of the opening if suc distribution is preferred; but this particularity is not indispensable either. The rail support, according to this invention, fully pervades the objective striven for, given the fact that it provides all advantages of the so-called "packing" method in an economical, automatic mode, eliminating all of the time-consuming, expensive operations of the method which have been described above, and does so by recurring to the very same phenomenon which causes the settlement, to automatically correct and compensate its effects. The replenishing of the cavities with small grade ballast or pea gravel is the only exterior intervention, and the replenishing lends iself easily to mechan- isation, because the cavities can be designed to be very accessible, such as in the example shown above. Design changes can be realized without altering the applicability of the invention. A single cavity-reservoir, for example, centered half-way between the two rails, can be connected with the bottom face of the tie underneath O P1 the rails, by an unspecified number of conduits, the openings of these conduits leading to the bottom of the rail support being of variable length or width, according to the desired effect and the required size of the bearing surface. In case of a railroad particularly subject to surface pollution, such as the ones operated with diεsel locomotives, for example, a removable cover can be installed to close each cavity. Alternatively, the openings can be placed in the upper part of the ends, or in the vertical faces of the crosstie sides. Finally, the concrete tie (1) given as an example of possible execution of the rail support, is not limitative, and the invention is applicable to all other types of crossties, as well as to large surface slab sections and pads, provided these various elements function as rail supports and transmit and distribute dynamic loads. It should be noted that in case of a hollow rail support, such as a steel crosstie for example, the cavity-reservoir may be attached to one or the other upper part of these crosssties. -BURfcA T OMPl C P TV '

Claims: CLAIMS What is claimed is: 1. A rail support comprising at least one cavity-reser¬ voir for small grade ballast or pea gravel, and at least one conduit means connecting the cavity-reservoir with the bottomface of said rail support in contact with underlying ballast, for allowing small grade ballast or pea gravel contained in said cavity-reservoir to flow out and distribute automatically underneath the rail support in proportion to the settlement of the subjacent ballast by the combined effects of gravity and the vertical oscillations induced by the passage of train wheel sets. 2. A rail support according to Claim 1 wherein the cavity-reservoir opens through an upper part of the vertical side faces of said rail support. 3. A rail support according to Claim 1, wherein the cavity-reservoir opens through an upper portion of the support's vertical end face. 4. A rail support according to Claim 1 wherein the cavity-reservoir is attached to an upper portion of the rail support. 5. A rail support according to Claim 1, wherein the cavity-reservoir is protected by a removable cover which seals out exterior pollutants. 6. A rail support according to Claim 1, wherein the conduit means connecting the cavity-reservoir with the bottomface of the rail support is conical. jUR E At OMPI

Inventors: MOEHREN H
Applicants: MOEHREN H
Application year: 1978
Main classification: E01B3
IPC codes: E01B3, E01B27