The RP20CD is a diesel-electric road switcher

Road switcher

A road switcher is a type of railroad locomotive used for delivering or picking up cars outside of a railroad yard. Since the road switcher must work some distance away from a yard, it needs to be able to operate at road speeds, it must also have high-visibility while it is switching, and it must...

 locomotive built by Railpower Technologies

RailPower Technologies

Railpower Technologies Corp. is a subsidiary of R.J. Corman Railroad Group that builds environmentally friendly hybrid and genset yard locomotives, founded by Frank Donnelly and Gerard Koldyk...

. It is a "genset

Engine-generator

An engine-generator is the combination of an electrical generator and an engine mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set...

" locomotive, having three engine-generator sets.

The engines are computer controlled, with the computer stopping and starting engines on a rotating basis, as required to produce the horsepower needed at any given moment.

It has six-wheel trucks

Bogie

A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...

, rather than the usual four-wheel trucks commonly found on smaller, lighter, switcher

Switcher

A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...

locomotives. RP20CDs are rebuilt from older locomotives and can be upgraded to 2700 hp by adding a fourth generator.