Superstructure W
The superstructure W is a rail fastening developed by Vossloh on concrete sleepers .
The thresholds used for this are specially shaped at the two attachment points. They have depressions there, the profile of which is reminiscent of a W stretched out in width: a V-shaped depression on each of the two edges and in between a broad plane about half as deep. An angle guide plate Wfp made of steel or plastic belonging to the system is inserted at the edges to guide the rail foot sideways. The angle guide plates have a V-shaped bar on the underside that engages in the corresponding groove in the sleeper. This form fit facilitates assembly: the inserted angled guide plates form the right width for the rail foot between them. The bar on the angled guide plate also increases the height of the surface over which the horizontal guide force is introduced into the concrete. The rail inclination, generally 1:40 for sleepers in Germany, is incorporated into the sleeper body.
The rails are fastened through a hole in the angle guide plates with sleeper screws to be screwed into plastic dowels in the sleeper. The latter are standard screws for concrete sleepers. Between the sleeper screw and the rail foot, the Epsilon tension clamp is also an (elastic) fastening element that was standardized earlier. The angle guide plates have the necessary mounting points for this: a groove above the V on the outside (in which the legs of the middle loop are supported) and a bracket (or a bar) inside (as a stop for the arch of the middle loop, when it is reached the screwing in of the screw stops is).
The sleepers are supplied with pre-assembled fastening parts, of which the tension clamps are inserted rotated by 180 °. The space for setting down the rails is thus free. Before fastening, they are rotated into the operating position and pushed against the rails before the sleeper screws are tightened. For installation with high-speed construction machines, tension clamps with a longer middle loop were introduced, which are not twisted, are only preassembled further out and thus also leave the space free for setting the rails. This eliminates the need to turn it into the operating position, which cannot be easily performed by machine.
A disadvantage of the superstructure W has long been that a separate sleeper shape was required for each rail foot width. With longer angled guide plates and tension clamps, it has been possible since around 2015 to mount rails with a foot width of 125 mm on thresholds intended for 150 mm foot width.
In Germany, sleeper types B70 for standard applications, B90 in reinforced design as transition to turnout sleepers or for path crossings and block sleepers with vertical rails as turnout sleepers and installation between switches or crossings that are close together are common for long-distance railway applications. There are also special sleepers with a reduced overall height for tram applications with grooved rails and different track widths. In many countries licensees manufacture their own sleepers with rail fastening W. The Spanish traviesas polivalentes occupy a special position with built-in rail mounts for standard and Iberian broad gauge , which make it possible to reroute the lying track in both directions by simply moving the angled guide plates, if necessary several times. They have been installed since 1991.
literature
Joachim Fiedler: Railways. Planning, construction and operation of railways, S, U, light rail and trams. 5th edition. Werner Verlag / Wolters Kluwer Germany, Munich / Unterschleißheim 2005, ISBN 3-8041-1612-4 , p. 112.