TY JOUR TI ENERGY POTENTIAL OF THE WHEELED 4К4б GENERAL-PURPOSE TRACTORS KW power ratio KW potential KW kind of cultivation KW propulsive efficiency KW slipping KW operational mode JO Bulletin of KSAU AU Selivanov, N.I. AU Zaprudsky, V.N. PY 2012 IS PB Krasnoyarsk State Agrarian University