maximum speed, vehicle weight, acceleration rate and the railway slope all influence a motor's performance specifications. added to that, the requirements of the auxiliary systems also need to be considered, such air-conditioning units, motor cooling systems, brake compressors and in some cases the need for a separate power supply to run the air-conditioning and heating systems of each passenger car. here, a range of diesel motors can be selected, from large frame v-motors for locomotives to flat 6-cylinder sub-floor motors for motorized railcars or even the compact 12-cylinder motors often used by utility vehicles. for most modern motorized railcars, the preferred solution is a sub-floor mounted motor and transmission combination.