Laboratory Tests of Idlers Rotational Resistance – Selected Issues

AbstractIdlers rotational resistance has a significant impact on energy consumption of belt conveyors. The conducted analyses showed that this component can account for 30% of total belt conveyor resistance to motion (Gładysiewicz and Kawalec, 2008; Błażej et al., 2013). The causes for idlers rotational resistance including structural factors were precisely determined in (Gładysiewicz and Król, 2005). Since then, many works have been carried out with the aim to assess the quality of idlers and to acquire the knowledge necessary to optimize belt conveyor haulage process (Bukowski et al., 2011a, Gładysiewicz and Król, 2009; 2012). It was due to, inter alia, the fact that the calculations of belt conveyors designs are based only on empirical relationships which give a good approximation for laboratory tested idlers, but are imprecise in relation to new construction solutions of idlers.The results of research and development works carried out at the Wroclaw University of Technology have shown that one of the conditions for successful reduction of the energy consumption of belt conveyors drives is to use high-quality idlers characterized by low rotational resistance under a wide range of working loads (Bukowski et al., 2011c, Król and Kisielewski 2014). The studies allowed expanding knowledge about idlers rotational resistance and about the impact of working loads on belt conveyors resistance to motion and showed that idlers rotational resistance depends also on value of the idlers radial loads caused by transported masses. A series of laboratory and operational tests based on using advanced analytical tools and modern measuring techniques have been carried out and allowed to observe dependence between instantaneous mass output of belt conveyor and loads of individual idlers in the set. This allowed determining the dependence of idlers rotational resistance as a function of random loading of transported bulk material (Bukowski 2012, Król 2013)