Measurement of train traction characteristics

This paper describes an attempt to develop empirical equations that could be used to estimate some traction characteristics of a generic type of train and vehicles that are in use in Serbia and Montenegro. As the running resistance of present freight trains in Serbia and Montenegro has not been investigated, the Serbian Railways and the Department of Mechanical Engineering at the Institute of Transportation CIP, took the initiative to investigate this matter. Miscellaneous formulas of running resistance used in Serbia and Montenegro and other countries gave considerably different results when they were applied to a mixed freight train of the same consist. So, they could not be considered reliable for the average mixed freight train in use at the JZ (Serbian Railways). The well-known method of least squares is used to determine the function and correlation coefficients that best represent experimental measurements and are applied to experimental data. All calculations are conducted on the basis of the data received during test runs. The traction characteristics are measured by pulling: that is, by measuring the tractive effort at the draw bar between locomotive and dynamometer car, and by determining the coefficients by means of the least squares method. On the basis of several experimental runs, the basic traction characteristics are determined and compared with that generated by modern formulas.