Locomotive means a piece of railroad on-track equipment, other than hi-rail, specialized maintenance, or other similar equipment, which may consist of one or more units operated from a single control stand -
(1) With one or more propelling motors designed for moving other railroad equipment;
(2) With one or more propelling motors designed to transport freight or passenger traffic or both; or
(3) Without propelling motors but with one or more control stands.
49 CFR § 232.5
The definitions in this section are intended to clarify the meaning of terms used in this part.