OBRABOTKAMETALLOV TECHNOLOGY Vol. 24 No. 3 2022 Later SRL became a part of the Vossloh group and today the HSG method is its unique technology. Using this technology and the accumulated experience of operating the RC-01 grinding train, Vossloh continued to develop this method and in 2010 manufactured a new rail grinding train – the HSG-2 (Fig. 3). The new machine uses the same HSG method (Fig. 2, a), while the maximum operating speed of the train is increased to 100 km/h [15]. Fig. 2. Railway grinding train RC-01: a – grinding schematic diagram; b – general view of the grinding equipment а b a b Fig. 3. Railway grinding train HSG-2: a – general view of HSG-2; b – general view of grinding equipment HSG-2 Invention of the new grinder made Vossloh the fi rst private company to provide preventive maintenance services for high-speed railway sections in Europe and China. With all these positive aspects, however, the HSG method does have a disadvantage. The main negative side of the passive grinding method with the periphery of the grinding wheel is the need of breaking-in the abrasive tool to the worked transverse profi le of the rail. When the grinding process begins, the grinding wheel has a cylindrical shape and is only in contact with the rail along the rolling surface (Fig. 4,a). As grinding proceeds, the abrasive wheel begins to wear out and takes on the shape of the rail profi le, while the contact of the wheel with the rail increases (Fig. 4,b). With further processing, the abrasive wheel starts to grind both the upper and lateral working surfaces of the rail (Fig. 4, c). Thus, a certain amount of time must pass from the moment the grinding starts to the full breaking-in of the abrasive tool. Considering that the operating speed of the rail grinding train is about 100 km/h, the train passes a signifi cant part of the track on which the rail profi le remains incompletely processed. In addition, it should be noted that the geometry of the transverse profi le of the rail on different sections of the railway track may not be the same, i.e. it can be assumed that under certain conditions, the abrasive wheels may
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