Model (Scale 1:8), semi-portable overtype engine, by Robey & Co.

Model of Overtype Semi-portable Engine

Model (Scale 1:8), semi-portable overtype engine, by Robey & Co, 1920. The idea of a portable steam engine became a practicable idea with the introduction of high-pressure non-condensing engines, pioneered by Richard Trevithick (1771-1833). This type of engine was quite easily transported (being self-contained) and needed practically no foundations. However, not being mounted on wheels it was intended for more permanent situations than the fully portable engine. It is called an 'Overtype' engine as the cylinder is mounted on top of (or over) the boiler.