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RTR 4/2010 20 then, normal rail grades of steel had been used for these point components, although it should be added that it was only possible to apply pearlite tempering to crossing noses afterwards. In the most positive of cases, however, this treatment only penetrated as deep as 15 millimetres below the surface. Moreover, complicated bolt fastenings also used to be necessary for wing rails and crossings, which used to be made of rolled steel. As a material, Cogidur overcomes these shortcomings. Thanks to volume tempering, for which the steel producer provides a guarantee, the crossing takes on a homogeneous hardened grain structure. It is also possible for it to be milled from a monobloc, along with the wing rails, and these parts thus do not need to be bolted together. Given that the material is supplied in the form of plate, it is possible to cut all contours and geometries, and the specific running geometries, which are always unique The points in the railway networks of local public transport are subject to particularly heavy loads. At ten tonnes, the axle load of trams is admittedly much lower than that of freight trains, but trams run through neuralgic junctions several times per minute. One result of this is the severe curtailment of the service life of crossings and switch blades made of conventional rolled steel. In the search for materials that are going to last longer, even top-grade rolled steels have to be ruled out as an inadequate alternative. If rails with a tensile strength of 1080 N/mm2 are to be welded in the field they must be preheated to temperatures of up to 400° Celsius. It takes a huge effort to get the necessary energy into steel lying on railway lines. A further consideration is that excessive temperatures affecting other materials right next to the points (such as asphalt, tar or cobble stones) will cause serious impairment to them. 1 Fundamental considerations Vossloh Laeis has been using a wear-resistant grade of steel known as Cogidur in the manufacture of points since 2001. The crucial advantage of this material resides in the combination of its high wear resistance and its good weldability. It has a tensile strength of 1200 N/mm2 and a Brinell hardness of 400 HB and lends itself to welding if preheated to temperatures between 100° and 150° Celsius. It is thus easy to process Cogidur in the factory. In addition, welding repairs on points are so simple that users are able to perform them themselves. Cogidur is typically delivered in the form of a plate metal with edge lengths of 6000 x 2000 x 100 millimetres (length x width x thickness). Today, plates with a thickness of 160 millimetres can also be delivered. Cogidur’s uses include armour plating, cutting edges and loading shovels on machines used in civil engineering and mining. Track components made of Cogidur have also been incorporated in the general railway network for several years and have established a reputation for particular durability and strength. Vossloh has now also developed a use for Cogidur in the construction of railway points. 2 Track components in Cogidur steel It was in 2001 that Cogidur steel was first used as a material for the manufacture of switch blades and point crossings. Up until Hard steel for every type of point Vossloh Laeis, a manufacturer of railway points, makes use of a material known as “Cogidur” for the purpose of lengthening the service life of points. Cogidur is a material that is harder than the steel normally used for rails. Moreover, it lends itself to welding even at low preheating temperatures. Head of engineering Vossloh Laeis, Trier works info@vossloh-laeis.de Dipl. Ing. (FH) Albert Gelz Fig. 1: Complete point installation made of Cogidur for Rotterdam’s Central Station (All photographs: Vossloh Laeis)

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