A Steam roller (or steamroller) is a form of road roller – a type of heavy construction machinery used for flattening/compacting surfaces, such as roads or airfields – that is powered by a steam engine. The levelling/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 normal road wheels with a treaded face.
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.
In many parts of the world, the term steam roller is still used to refer to a road roller, regardless of the method of propulsion. This typically only applies to the largest examples (used for road-making).
This article concentrates on steam-powered rollers; see road roller for a description of motor (eg diesel) rollers.
The majority of rollers were of the same basic configuration, with two large smooth wheels at the back and a single wide roll at the front. However, there was also a distinctive variant, the tandem, which had two wide rolls, one front, one rear (see photo). This configuration is still used frequently for small motor road rollers for use on minor pavement and road repairs.
Another variation was the convertible: a combined engine which could be either a steam roller or a traction engine and could be changed from one form to the other in a relatively short time – i.e. less than half a day. Convertible engines were liked by local authorities since the same machine could be used for haulage in the winter and road-mending in the summer (for example).
Although most steam roller designs are derived from traction engines, and were manufactured by the same companies, there are a number of features that set them apart.
The most obvious difference is in the wheels. All traction engines were built with large fabricated spoked steel wheels with wide rims. Those intended for road use would have continuous solid rubber 'tyres' bolted around the rims, to improve traction on tarmac. Engines intended for agricultural use would have a series of 'strakes' bolted diagonally across the rims (like the tread on a modern pneumatic tractor tyre), and the wheels were typically wider to spread the load more evenly.
Steam rollers, on the other hand, had smooth rear wheels and a roller at the front. The roller was a single wide cylinder supported at either end. This replaced the separate wheels and axle of a traction engine.
In the conventional arrangement, the front roller is mounted centrally, forward of the chimney. In order to allow enough clearance from the boiler (and hence a larger front roll), the smokebox is extended forward substantially at the top to incorporate a support plate on which to mount the bearing for the roller assembly. This gives the distinctive 'hooded' look to the front of a steam roller. It also necessitates a different design of smokebox door – it has to drop down, rather than opening sideways, due to the limited access available.
The rear rollers were fitted with scraper bars. As the vehicle moved along, these removed any surface material that had become stuck to the roll, to prevent a build-up of material and ensure a flat finish was maintained.
Some steam rollers were fitted with a scarifier mounted on the tender box at the rear. They could be swung down to road level and used to rip up the old surface before a road was remade.
Another 'extra' was a tar sprayer - a bar mounted on the back of the roller. This was not a common fixture but a number of Tar spayer rollers survived into preservation.Only a few now remin as several have in recent years been tripped of the equipment when rollers were a popular 'donor' vehicle to convert to Showman's Engine due to the desirability of Showmens and low value of rollers. conversions are a controversial subject now and the practice is becoming less common.
A number of companies owned fleets of steam rollers and contracted them out to local authorities.
Many were still in use into the 1960s, and part of the M1 motorway was made with the help of steam rollers.
A few steam rollers were still being used for road maintenance in the early 1970s, and this may go some way to explaining why road rollers are still colloquially known as steam rollers to this day.
Britain was a large exporter of steam rollers to the world over the years with the firm of Aveling & Porter probably being the most famous and the most prolific.
Other nations had makers including the Czechs, Swiss, Swedes, Germans and Dutch which produced steam rollers;
- Albaret - France
- Buffalo-Pitts - USA
- Buffalo-Springfield - USA
- Henschel - Germany
- Ruthemeyer - Germany
- Zettelmeyer - Germany
Many steam rollers are preserved in operating condition, and can be seen in operation during special live steam festivals, where operating minature steam engines and scale models may also be displayed.
In popular cultureEdit
Famous Steam RollersEdit
- British steeplejack and engineering enthusiast Fred Dibnah was known as a National Institution in Great Britain for the conservation of steam rollers and traction engines. The first engine he restored to working order was an Aveling & Porter steam roller, registration no. DM 3079. Built in 1912, it was a 10 ton slide-valve, single-cylinder, 4-shaft, road roller. 
Originally named "Allison", after his first wife, Fred renamed the engine "Betsy" (his mother's name) following his divorce – Fred's view being "wives may change but your mother remains your mother!"
This roller was featured in many of Fred's early television programmes. It may still be seen at steam rallies in Britain and was in steam at the Great Dorset Steam Fair in 2006, working in the road-mending demonstration.
(for full details see original source)
- Roley is one of the main vehicle characters in the children's books and TV series, Bob the Builder. He is a green roller with a cab, enclosed power unit and no chimney, and so is obviously diesel-powered - nevertheless, his official title is Roley the Steamroller. This is another example of why the use of 'steam roller', to describe a modern road roller, still persists in the English language.
Wikipedia for base article, (for original see below)
- Traction engine
- Road roller – internal-combustion-powered road rollers
- Roller (agricultural tool) – for farm rollers
- Paddys motorbike – nickname for another type of compaction vehicle.
- Steam engine
- Steam tractor
- List of Steam Machinery Manufacturers
- Road Roller Association – UK-based society dedicated to the preservation of steam (and motor) rollers and ancillary road-making equipment.
- "Steam Dinosaur" – world's oldest surviving traction engine: immediate ancestor of Aveling's earliest rollers.
(Article includes lots of detail about early Aveling roller design.)
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