Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a 2-6-6-0 is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels, and no trailing wheels. The wheel arrangement was principally used on Mallet-type articulated locomotives, although some tank locomotive examples were also built.
Other equivalent classifications are:
- UIC classification: 1CC (also known as German classification and Italian classification)
- French classification: 130+030
- Turkish classification: 34+33
- Swiss classification: 3/4+3/3
Read more about 2-6-6-0: Overview