DPU (Distributed Power Unit)
A locomotive controlled from the lead locomotive but positioned elsewhere in the train, often in the middle or at the rear. Distributed power can help manage forces and braking on long or heavy trains.
Consist
The group of locomotives or cars that make up a train. Railfans also use the word when discussing the locomotive lineup.
Siding
A track connected to the main line that allows trains to meet, pass, or temporarily clear the main track.
Yard
A group of tracks used to sort, assemble, inspect, store, or service railroad cars and locomotives.
Distributed Power
Locomotives placed away from the lead end of a train and controlled from the lead locomotive to improve train handling.
Dynamic Braking
A system that uses traction motors as generators to help slow a locomotive or train without relying only on friction brakes.
Head End
The front of a train, especially the locomotive end.
Rear End
The back of the train, historically associated with the caboose and today often with an end-of-train device.
Interchange
The transfer of railroad cars or traffic between two railroads.
Main line
A railroad’s principal through route, generally used for movements between terminals and major points rather than only local switching.
Slow order
A temporary instruction requiring trains to operate below the normal authorized speed over a specified section of track, often because of track conditions or maintenance work.
Train consist
The locomotives and cars that make up a particular train. The word “consist” can also be used more narrowly for a group of locomotives coupled and operating together.
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