4-4-6

A 4-4-6, in the Whyte notation for the classification of steam locomotives by wheel arrangement, is a locomotive with:

• 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).

4-4-6 locomotive

The only example of this wheel arrangement was the Thuile locomotive.

Other equivalent classifications are:

• UIC classification: 2'B3' (also known as German classification
• Italian classification), and
• French classification: 223.