Steamroller

A steamroller (or steam roller) is a form of road roller – a type of heavy construction machinery used for leveling surfaces, such as roads or airfields – that is powered by a steam engine. The leveling/flattening action is achieved through a combination of the size and weight of the vehicle and the rolls: the smooth wheels and the large cylinder or drum fitted in place of treaded road wheels.

The majority of steam rollers are outwardly similar to traction engines as many traction engine manufacturers later produced rollers based on their existing designs, and the patents owned by certain roller manufacturers tended to influence the general arrangements used by others. The key difference between the two vehicles is that on a roller the main roll replaces the front wheels and axle that would be fitted to a traction engine, and the driving wheels are smooth-tired.

The word steamroller frequently refers to road rollers in general, regardless of the method of propulsion.

Before about 1850, the word steamroller meant a fixed machine for rolling and curving steel plates for boilers and ships. From then on, it also meant a mobile device for flattening ground. An early steamroller was patented by Louis Lemoine in France in 1859 and demonstrated sometime before February 1861. In Britain, a 30-ton steamroller was designed in 1863 by William Clark and partner W.F. Batho. Having failed to impress the British municipal road authorities, it was transferred to Kolkata, where it continued to work.

The company Aveling and Porter was the first to successfully sell the product commercially and subsequently became the largest manufacturer in Britain. In 1866 they produced a prototype roller with 3-foot-wide (90 cm) rollers fitted to the rear of a standard 12-nominal-horsepower traction engine. This experimental machine was described by local papers as 'the world's first steamroller' and it caused a public spectacle.

In 1867, the steam road roller was patented and the company began production of the first practical steam roller – the new machine's rollers were mounted at the front instead of the back and it weighed in excess of 30 tons. It was tested on the Military Road in Chatham, Star Hill in Rochester and in Hyde Park, London, and the machine proved a huge success. Within a year, they were being exported around the world, including to France, India and the United States. A New York City chief engineer said of one of these, that "in one day's rolling at a cost of 10 dollars, as much work was accomplished as in two days' rolling with a 7 ton roller drawn by eight horses at a cost of 20 dollars a day." The heavier rollers were found to be hard to handle, and the weight of the machines was reduced to around 10 tons.

Aveling and Porter refined their product continuously over the following decades, introducing fully steerable front rollers and compound steam engines at the 1881 Royal Agricultural Show. The move to asphalt for road construction resulted in the demand for steamrollers that could rapidly reverse so they could roll the tar while still hot. Machines that could do this were introduced in the first decade of the 20th century.

Production ended around 1950.