TY JOUR TI Method for determining the primary obstacle to motion of freight wagons during running brake tests KW freight wagon KW resistance to movement KW energy efficiency of the wagon KW running brake tests JO Bulletin of scientific research results AU Boronenko, Y.P. AU Komaydanov, A.A. PY 2026 IS 2026 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"