2-6-6T

In the Whyte notation for describing steam locomotive wheel arrangement, a 2-6-6 is a locomotive with a two-wheeled leading truck, six driving wheels, and a six-wheeled trailing truck. All the locomotives produced of this arrangement have been tank locomotives, and the vast majority in the United States. It was a popular arrangement for the larger Mason Bogies, as well as some of the largest suburban tank locomotives.

ALCO-built 2-6-6 suburban tank locomotive of the New York Central and Hudson River Railroad.

The locomotive was mostly used in the Denver, South Park and Pacific Railroad.^[1][2] It also saw usage in New York and Chicago.^[3]

Equivalent classifications

Other equivalent classifications are:

• UIC classification: 1C3 (also known as German classification and Italian classification)
• French classification: 133
• Turkish classification: 37
• Swiss classification: 3/7