Railpower RP20CD

The RP20CD is a diesel-electric road switcher locomotive built by Railpower Technologies. It is a "genset" 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, rather than the usual four-wheel trucks commonly found on smaller, lighter, switcher locomotives. RP20CDs are rebuilt from older locomotives and can be upgraded to by adding a fourth generator.