4-4-6



A 4-4-6, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with: The only example of this wheel arrangement was the Thuile locomotive.
 * four (4) leading wheels (at the front of the locomotive)
 * four (4) driving wheels (2 axles) fixed in a rigid frame, and
 * six (6) trailing wheels (normally mounted in a trailing truck).

Other equivalent classifications are:
 * UIC classification: 2'B3' (also known as German classification
 * Italian classification), and
 * French classification: 223.