Various suffixes are sometimes used, but they are not universal. Some of the more common ones are:
|T||indicates a tank locomotive. In British practice, this is sometimes extended to indicate the type of tank locomotive: T means side tank, PT pannier tank, ST saddle tank, WT well tank. T+T means a tank locomotive that has a tender for additional coal or water capacity.|
|R||In Europe suffix R means rack (0-6-0RT) or it could mean reversible (0-6-0TR).|
|F||indicates a fireless locomotive (0-4-0F). Note that this locomotive has no tender.|
|ca||compressed air (i.e., running on compressed air from a tank instead of steam).|
|ng||narrow-gauge locomotives (i.e., less than 56.5 in / 1435 mm)|
In Britain, a small diesel or petrol locomotive is classified in the same way as steam locomotives, e.g. 0-4-0, 0-6-0, followed by D for diesel, P petrol, and another letter describing the transmission: E for electric, H hydraulic, M mechanical. Thus 0-6-0DE denotes a six-wheel diesel locomotive with electric transmission.
Where the axles are coupled by chains or shafts (rather than side-rods), or are individually driven, the terms 4w, 6w or 8w are generally used. Thus 4wPE indicates a four-wheel petrol locomotive with electric transmission. For large diesel locomotives the standard UIC classification is used.