Patent Application
20140231534
The present invention relates to an end restraint for a railroad rail. More particularly this invention concerns a resilient end restraint for use at a turnout.
Railroad tracks are typically secured in critical locations such as turnouts where significant forces are exerted transverse to the tracks, with special end restraints. To this end the tracks are fixed to rail plates extending transverse to the tracks, and each end of each rail plate is in turn secured to the underlayment, typically of concrete in a high-stress area, by a respective resilient end restraint, such as described in U.S. Pat. Nos. 7,766,249, 8,056,826, or 8,210,444.
Such devices are extremely effective in preventing potentially harmful lateral shifting of the rails and rail plate. Under normal use, however, each end restraint is largely responsible only for bracing the track in one direction, that is the end restraint at one end is responsible for resisting movement transverse to the tracks in an outward direction toward that one restraint, and the restraint at the other end is responsible for resisting opposite forces.
As a result it is necessary to construct these end restraints each to withstand considerable forces, since they are primarily working one at a time.
It is therefore an object of the present invention to provide an improved end restraint.
Another object is the provision of such an improved resilient end restraint that overcomes the above-given disadvantages, in particular that is effective in compression in both directions.
A further object is to provide such an end restraint that is simple to manufacture, will have a long service life, and is easy to install and position.
An assembly for securing at least one rail to a substrate has according to the invention a laterally extending rail plate extending across and secured transversely underneath the rail and having a pair of opposite ends. Respective resilient end restraints at the ends of the rail plate each have a jaw fixed to the respective end of the rail plate and each formed with a vertically throughgoing passage. A respective rigid anchor hood is fixed to the substrate in each of the passages with an outer surface of the anchor hood spaced inward from an inner surface of the respective passage and forming an annular space therewith. A respective rubber bumper mass fills each of these spaces so that forces transverse to the rail are transmitted through the bumpers to the anchor hoods.
The considerable advantage of this system is that forces transverse to the tracks in both directions are resisted primarily in compression by both of the end restraints. In fact, the end restraint on one end of the rail plate has its jaw in compression and tension and the end restraint on the opposite end of the rail plate also has its jaw in compression and tension when a train passes, for instance in a turnout. Thus each turnout need only be designed to resist half the maximum load, making it a significantly less expensive piece of hardware to build.
According to the invention the anchor hoods are fixedly bolted to the substrate. The rail plate is similarly fixedly bolted to the jaws, normally using permanent fasteners such as so-called Huck bolts.
The anchor hood in accordance with the invention is, seen from above, of T-shape and the hole in the jaw is generally complementary so that faces of the anchor hood and jaw that confront each other extend parallel to the rails for compression and tension of the bumper on shifting of the rail, rail plate, and jaws transverse to the rail.
According to further features of the invention a rubber-metal compression pad is provided underneath and engaging the rail plate and is fixed between the rail plate and the substrate. Such a compression pad is primarily fixed in place by the end restraints.
The metal plate imbedded in the compression pad in accordance with the invention has upwardly extending side-edge flanges between which the rail plate fits so that it cannot move parallel to the rails relative to the rail plate. It also has a pair of downwardly extending end flanges that limit lateral displacement of the compression pad between the end restraints.
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:
As seen in
The assembly comprises a thick steel rail plate 10 to is which the rails R are fixed by, for instance, unillustrated spring clips secured in eyes 11, although other anchors are usable. The rail plate 10 sits via a compression pad 20 on a solid substrate normally made of concrete and shown schematically at 29 in
The track plate 10 is permanently fixed at each end by three so-called Huck bolts 12 to a flange 31 of a respective cast-iron jaw 30 each engaged via a respective rubber mass 40 (
The compression pad 20 as shown in
The compression pad 20 is formed at each end with three holes 21 that fit loosely around the bolts 50 underneath the flange 31 of the jaw 30 at the respective end of the plate 20.
Furthermore a lower rubber face 26 of the compression pad 20 is generally planar and lies in permanent surface-to-surface contact with the planar upper face of the substrate 29. This lower face 26 is formed with an array of recess 27 within which are formed bumps 28 whose lower end faces are spaced above the plane of the lower face 26. As a result vertical compression of the compression pad 20 has a dual spring characteristic that increases markedly when it is vertically compressed sufficiently to engage the lower faces of the bumps 28 with the substrate 29. The result is that the compression pad 20 resists compression when first loaded vertically up to a predetermined force, but when the load increases sufficiently that the bumps 28 engage the substrate 29, this resistance to compression increases markedly and further vertical compression is resisted with a significantly higher spring force. This means that it is not necessary to tradeoff performance with a heavy load, such as from a locomotive, against that of a lighter load, such as a passenger car, because the system will automatically respond to the higher load, when it is present, with a higher spring force.
Each jaw 30 has a flange 31 that is flat and horizontal but formed with upstanding collars 32 that project upward through the rubber mass 40. Furthermore, the jaw 30 has an annular part 33 outward of the respective flange 31 that surrounds the outer surfaces of the respective anchor hood 60. The part 33 has a generally T-shaped, stepped, and vertically throughgoing passage or drain hole 34 that is complementary to the vertical footprint or profile of the anchor hood 60, but somewhat larger so as to spacedly surround the anchor hood 60 on two sides. This annular space between the anchor hood 60 and the inner surface of the jaw 30 is filled by the bumper/ mass 40 that also covers virtually all of the outer surfaces of the jaw 30 except its lower face and upper end faces of the collars 32 of the flange 31. Each anchor hood 60 further has as shown in
This construction allows the jaw 30, together with the plate 10, to move laterally, that is parallel to the elongated rail plate 10 and transversely to the rails R, limitedly relative to the substrate 29 to which the anchor hoods 60 are anchored by the bolts 50. Since one such jaw 30 is provided at each end of the rail plate 10, this means that transverse or longitudinal forces effective on the rails R are shared by both of the end-restraint assemblies each formed by one anchor hood 60, one mass 40, and one jaw 30 having the annular part 33, so that each such assembly has to withstand half the lateral forces of the conventional such assemblies that only resist forces that are outward away from and perpendicular to the rails R, one of the assemblies working mainly in compression and the other mainly in tension.
As shown in
