Cable driven Automated People Movers for urban applications: modelling the roller for investigating energy consumption / Impianti automatici con trazione a fune per trasporti urbani: modellazione dei rulli per la verifica del consumo energetico

The importance of cable driven APMs (Automated People Movers) has become much higher in the recent years, for hourly capacities up to nearly 8-9 thousand passengers per direction. This is due also to their undeniably competitive energy consumption per passenger and per km since they do not need to be provided with a motor on board and - consequently - neither the mechanical transmission to the wheels nor a structure suitable for such weights; this leaves power transmission to a mechanical component with small inertia, such as a steel wire rope. However, in any rope transport system based on a carrying-hauling rope, a relevant part of energy losses comes from rollers and related roller assemblies, in particular from the interaction between the metal rope and the rubber on rollers. So, having the possibility to quantify and, possibly, reduce their contribution to energy losses may result in positive effect on the overall energy performance of APMs. The temperature of rubber increases under cyclic loads; this is due to hysteresis losses and low rubber thermal conductivity. This paper presents a new procedure to assess the generation of heat in the ropeway roller with rubber band. The procedure consists in assessing hysteresis loss, i.e. the dissipated energy within the rubber band, by an analytical procedure. The model works with a limited number of data and without direct experimental measures on the rubber compound, which would be hardly feasible in practice. The dissipated energy obtained was used as an input for steady state thermal analysis. Verification of the proposed procedure was performed by comparing the simulation results to the data obtained experimentally during the periodical tests that have been developed in various plants. This model allows obtaining a preliminary value about the actual roller energy consumption, in order to provide a better comparison between different urban transport systems in terms of energy consumption.