0-6-6-0

An 0-6-6-0 of the New York Central Railroad.

In Whyte notation, a 0-6-6-0 is a railroad steam locomotive that has two articulated sections, each with six coupled driving wheels, without any leading wheels or trailing wheels.

Equivalent classifications

Other equivalent classifications are:

• UIC classification: CC (also known as German classification and Italian classification)
• French classification: 030+030
• Turkish classification: 33+33
• Swiss classification: 3/3+3/3

United States

The first Mallet locomotive built in the United States, Baltimore and Ohio Railroad #2400 (Class O), was of this type. The Kansas City Southern used them as freight engines, with pilots, and had the most at 12 locomotives. 0-6-6-0's were also used, in limited amounts, on logging railroads and in mountain terminals.

United Kingdom

The only example of this type of engine in the UK was the Leader. It was originally commissioned by the Southern Railway but it was completed by British Railways in 1949. It was effectively a Meyer locomotive since both sets of drivers were articulated. In UIC classification this would be written C'C'.

Ireland

Córas Iompair Éireann No. CC1, generally known as the Turf Burner, was a prototype 0-6-6-0 articulated steam locomotive designed by Oliver Bulleid CC1 shared some of the characteristics of Bulleid's previous attempt to develop a modern steam locomotive, the Leader. CC1 had a relatively short career and was never used in front-line service.

Canada

The only compound mallets to operate in Canada were R1 class 0-6-6-0 Vaughan design (cylinders back to back)locomotives, owned by the Canadian Pacific Railway, for service on the Big Hill in British Columbia, which had a 4.1% grade. They were built between 1909 and 1911. A 6th one was built, but had 2 sets of high-pressure cylinders, and was not a compound mallet. All of the locomotives in this class were converted to 2-10-0 types, and were used as shunting and transfer engines in Montreal.