Locomotive at the head of a train, which is immediately in front of the car. [Note 1] A leader locomotive, if any, is located in front of the train locomotive, an intermediate locomotive within the train set and a push or tail locomotive at the end of the train. In the case of multiple traction , no distinction is made between the leader and the pulling locomotive.
Railroad Lexicon . 5th edition. Transpress VEB Verlag, Berlin 1978, p.851 (keyword train locomotive ) .