Predominantly used just in Britain, these steam driven vehicles came in just two styles and were named after the placement of the vehicles engine, overtype and undertype. They became popular with makers such as Coulthard, Thornycroft and Leyland jumping on board.
By WW1 some of the more efficient makers such as Sentinel and Garrett had their entire production going towards the war effort. This of course left a gap, for other companies to form and develop.
By the early 1930's it was becoming obvious, that steam was no longer the way to go and diesel wagons were introduced.
Now you can only see steam driven trucks and wagons at fairs or in collections.