0-4-4-0

In the Whyte notation for the classification of steam locomotive wheel arrangement, a 0-4-4-0 is a locomotive with no leading truck, two sets of four driving wheels, and no trailing truck. Examples of this type were constructed as Mallet, Meyer and Double Fairlie locomotives. A similar configuration was used on some Garratts, but it is referred to as 0-4-0+0-4-0.

Other equivalent classifications are:

UIC classification: BB (also known as German classification and Italian classification)

French classification: 020+020

Turkish classification: 22+22

Swiss classification: 2/2+2/2

The UIC classification is refined to B'B for a Mallet locomotive or B'B' for a Meyer locomotive.

Eritrean Railways used many 0-4-4-0Ts. The last was built in their own shops in 1963, making it the last Mallet built in the world. (See [http://www.internationalsteam.co.uk/trains/eritrea1.htm] ).