If you’ve seen numbers like 0-4-0, 2-6-2 or similar describing a steam or model railway loco and wondered what they mean, this is for you.
The number sequences, such as 0-4-0, are a notation system describing how many wheels a locomotive has and their role. It’s used on both full size and model trains.
Whyte Notation format and definition.
It was created in the early 20th Century by a Dutch born American engineer, Frederick Methvan Whyte, whose name the notation is known after.
The format for Whyte Notation is x-y-z.
- x means the number of weight carrying wheels at the front,
- y denotes the number of driving (powered) wheels in the middle, and
- z relates to how many weight carrying wheels are at the rear of the loco.
So for an steam locomotive with four main drive wheels would be classified as 0-4-0 while an loco with two leading four wheels in front, three driving axles and then one trailing axle (two wheels) being classified as 4-6-2. The train pictured above would be 2-6-2, two front wheels, six main drive wheels and two at the rear.
In Britain, the notation was expanded after steam engines were replaced with further letters giving the nature of the locomotives power. D or P is appended for diesel or P, with each followed by a letter revealing the type of transmission – E for electric, H hydraulic, M mechanical. So a six-wheel diesel locomotive with electric transmission would be 0-6-0DE.
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#3 The Smallest Model Railway
#4 The World's largest model railway
#5 Whyte Notation
#6 Origins of Ballast
#7 Everything You Could Want To Know About Sleepers
#8 The Biggest Model Railway Mountain #9 The Man Who Built 600 Model Trains
#10 Model Railway Eras - A Question Of Time
> A final, personal, note: I spend a huge amount of time testing, photographing, writing and researching techniques for these articles and pay for all the running costs of MRE out of my own pocket. If you found this article useful you can support me by making a donation on my fund-raising page. Thanks and happy modelling, Andy.
Andy is a lifelong modeler, writer, and founder of modelrailwayengineer.com. He has been building model railways, dioramas, and miniatures for over 20 years. His passion for model making and railways began when he was a child, building his first layout at the age of seven.
Andy’s particular passion is making scenery and structures in 4mm scale, which he sells commercially. He is particularly interested in modelling the railways of South West England during the late Victorian/early Edwardian era, although he also enjoys making sci-fi and fantasy figures and dioramas. His website has won several awards, and he is a member of MERG (Model Railway Electronics Group) and the 009 Society.
When not making models, Andy lives in Surrey with his wife and teenage son. Other interests include history, science fiction, photography, and programming. Read more about Andy.