History of Traction Engines
A traction engine (sometimes called a road locomotive) is a wheeled steam engine used to move heavy loads, plough ground or to provide power at a chosen location.
The name derives from the Latin tractus, meaning 'drawn', since the prime function of any traction engine is to draw a load behind it. They are also known as "road locomotives" to distinguish them from (railway) steam locomotives - that is, steam engines that run on rails.
Traction engines tend to be large, robust and powerful, but extremely heavy, slow, and poorly maneuverable. Nevertheless, they revolutionized agriculture and road haulage at a time when the only alternative prime mover was the draught horse.
The machines typically have two large powered wheels at the back and two smaller wheels for steering at the front. However, some traction engines used a four-wheel-drive variation, and some experimented with a form of caterpillar track. They became popular in industrialised countries from around 1840, when the farm machinery company Ransomes of Ipswich developed a portable steam engine for agricultural use.Production continued well into the early part of the 20th century.
Traction engines were cumbersome and ill-suited to crossing soft or heavy ground so their agricultural use was usually either "in the belt" - powering farm machinery by means of a continuous leather belt driven by the flywheel - or in pairs, dragging an implement on a cable from one side of a field to another. However, where soil conditions permitted, direct hauling of implements ("off the drawbar") was preferred. Manufacturers continued to seek a solution to realise the economic benefits of direct-pull ploughing, and, particularly in North America, this led to the development of the steam tractor.
The earliest mobile steam engine is thought to have been invented by Nicolas Cugnot who demonstrated an engine for transporting heavy artillery pieces at the Paris arsenal on October 23, 1769. Unfortunately the idea was discredited when a similar engine ran into a brick wall during a demonstration in Paris.
The traction engine, in the form recognisable today, developed from an experiment in 1859 when Aveling and Porter modified a Clayton & Shuttleworth portable engine, which had to be hauled from job to job by horses, into a self-propelled one. The alteration was made by fitting a long driving chain between the crankshaft and the rear axle, and this set the basic design for the next 60-odd years.
All types of traction engines have now been superseded, in commercial use, by internal combustion engine -powered equivalents.