The operating conditions of light rail vehicles (trams, metro vehicles) are predominantly different compared with those of passenger or freight trains. The increased number of low-radii curves has a negative effect on wheel-rail interaction. The general design of light rail vehicle running gear is inherited from passenger trains and adapted to different loads. However, conventional solutions of a running gear may not provide smooth low-radius curve negotiation in all circumstances. In addition, a two-point contact is likely to occur, which, in turn, leads to accelerated wear of not only the wheels' tread but also their flanges. One of the proposals to deal with problems associated with the wheel-rail interaction in tight curves is implementing an automotive solution: a differential gear. The aim of the study is to investigate the dynamic behavior of a metro vehicle model equipped with differentials at each wheelset. The differentials were tested in two main variants: open and with internal friction torque. Internal friction torque value was set, consecutively, up to 2000 Nm. The results have shown that on tight curves a differential may improve rail vehicle wheel-rail interaction.
In this paper vehicle dynamic responses to clothoidal, sinusoidal and parabolic types of transition curves are considered. The responses such as vehicle motion and wheel-rail forces are significantly dependent on the type of curve. Also the dynamic interaction between the railway car and a track on a switch and a crossing of a standard turnout is considered. It was made for car-running direction "on" and "from" a switch facing point, and for nominal and geometrically imperfect track. The results imply the conclusion that specific transition curve and turnout parameters create a vital cause of dynamic interaction growth between a vehicle and a track.
The improvement of traveller comfort and safety, in parallel to an increase of passenger train speed, is a reason to implement monitoring systems. These systems are more often used to monitor components of railway infrastructure and vehicles. Studies in this area must be preceded by identification and a complex analysis of the railway vehicle - track system. This allows us to recognise the dynamic properties of the system and then select the appropriate place to install sensors on board the vehicle. This paper presents the results of model studies and a prototype monitoring system which is installed on a passenger electric traction unit. This system is aimed, inter alia, at monitoring the state of train suspension and the detection of some particular track geometric irregularities.
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