Traction electric drive systems are the most important part of electric locomotives. The auxiliary electrical system provides the required AC and DC power for the various auxiliary devices of the locomotive (various fans, air compressors, batteries) and the control operating system. The body frame, bogie, compressed air and braking system are basically the same as those of the diesel locomotive.

In fact, only steam locomotives must be made very large, internal combustion engines, electric motors, and substation equipment can not occupy the size of the locomotive. The EMU trains only use the extra space under a certain number of cars. I put them all up and ran faster than the traditional trains of organic cars.

The reason why internal combustion and electric locomotives should be as big as steam locomotives is mainly because the maximum traction of locomotives is directly proportional to the locomotive's own weight. If the weight is small, it will be as laborious as a child.