Mallet Locomotive - Terminology

Terminology

As a French speaking Swiss, Mallet pronounced his name accordingly, something like "Mallay".

Mallet's original patent specifies compound expansion, but after his death in 1919 many locomotives (particularly in the United States) were articulated Mallet style without using compounding (for instance the Union Pacific Big Boy). When fleets of such locomotives appeared in the middle 1920s the trade press naturally called them "Simple Mallets" — i.e., simple locomotives articulated like Mallets — but eventually the notion spread that this was somehow incorrect. The term "Mallet" continued to be widely used for simples as well as compounds, but some enthusiasts insist "simple Mallet" is an oxymoron.


Examples of Mallet locomotives
A preserved 2-6-6-2T Mallet
A 2-6-6-2 Mallet Locomotive at the Northwest Railway Museum in Snoqualmie, Washington
Portuguese Railways Mallet locomotive No. E168 at Povoa da Varzim, August 1970
Swedish-built Mallet locomotive DONJ No 12 in Jädraås, Sweden, August 2009
Russian Mallet locomotive Fita (Ө) series in 1905. Note piston valves on high pressure cylinders and slide valves on low pressure cylinders
"Union Pacific Big Boy", an example of a simple Mallet. This type is generally regarded as the largest steam locomotive in the world.

Read more about this topic:  Mallet Locomotive