A traction engine is a self-propelled steam engine used to move heavy loads on roads, 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 sometimes called 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 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.
They became popular in industrialised countries from around 1850, when the first self-propelled portable steam engines for agricultural use were developed. Production continued well into the early part of the 20th century, when competition from internal combustion engine -powered tractors saw them fall out of favour, although some continued in commercial use in the UK into the 1950s and later. All types of traction engines have now been superseded, in commercial use. However, several thousand examples have been preserved worldwide, many in working order. Steam fairs are held throughout the year in the UK, and in other countries, where visitors can experience working traction engines at close hand.
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 - in the U.S., this lead to the divergent development of the steam tractor.
History
Limits of technical knowledge and manufacturing technology meant that practicable road vehicles, powered by steam, did not start to appear until the early years of the 19th century.
The traction engine, in the form recognizable today, developed partly from an experiment in 1859 when Thomas Aveling 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. Other influences were existing vehicles which were the first to be referred to as traction engines such as the Boydell engines manufactured by various companies and those developed for road haulage by Bray. The first half of the 1860s was a period of great experimentation but by the end of the decade the standard form of the traction engine had evolved and would change little over the next sixty years.
Development of traction engines, and indeed all forms of steam road transport, was hampered in the UK by a series of government acts that tried to balance various competing interests, those of other types of vehicles as well as those maintaining the roads. Until the quality of roads improved there was little demand for faster vehicles and engines were geared accordingly to cope with their use on both roads and farm tracks.
Right through to the first decades of the twentieth century, manufacturers continued to seek a solution to realise the economic benefits of direct-pull ploughing, and, particularly in North America, this led to the American development of the steam tractor. British companies such as Mann's and Garrett developed potentially-viable direct ploughing engines, however market conditions were against them, and they failed to gain widespead popularity. These market conditions arose in the wake of the First World War when there was a glut of surplus equipment available as a result of British Government policy. Large numbers of Fowler ploughing engines had been constructed in order to increase the land under tillage during the war, and many new light Fordson F tractors had been imported from 1917 onwards.
The last new UK-built traction engines were constructed in the 1930s, although many continued in commercial use for many years, while there remained experienced enginemen available to drive them.
From the 1950s, the 'preservation movement' started to build up as enthusiasts realised that these lumbering beasts were in danger of dying out. Many of the remaining engines were snapped-up by enthusiasts, and restored to working order. Traction engine rallies began, initially as races between engine owners and their charges, later developing into the significant tourist attractions that takes place in many locations each year. It has been estimated that over two thousand traction engines have been preserved.
Operation
Although the first traction engines employed a chain drive, it is more typical for large gears to be used to transfer the drive from the crankshaft to the rear axle.
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 an early form of caterpillar track.
Types and usage
Traction engines saw commercial use in a variety of roles between the mid-nineteenth and mid-twentieth centuries. Each role required a machine with a different set of characteristics, and the traction engine evolved into a number of different types to suit these different roles.
Agricultural (general purpose) engine
The most common form in the countryside. They were used for hauling and as a stationary power source. Even when farmers did not own such a machine they would rely upon it from time to time. Many farms would use draught horses throughout the year, but during the harvest, threshing contractors would travel from farm to farm hauling the threshing machine which would be set up in the field and powered from the engine - a good example of the moveable stationary engine.
Some traction engines were designed to be convertible: the same basic machine could be fitted with either standard ('treaded' or tyred) road wheels, or else smooth rolls - the changeover between the two being achieved in less than half a day.
CHARLES BURRELL & SONS LTD.
No. 2421 : Built 1901: EB 3051 (Image)
No. 2933 : Built 1907 : CF 3507 (Image)
No. 3034 : Built 1908 : AF 3580 (Image)
No. 3131 : Built 1909 : FX 872 (Image)
No. 3474 : Built 1913 : SP 5348 (Image)
No. 3586 : Built 1914 : BP 5921 (Image)
No. 3763 : Built 1917 (Image)
No. 3917 : Built 1921 : TA 2374 (Image)
No. 4053 : Built 1926 : TD 8047 (Image)
DAVEY PAXMAN & CO. LTD.
No. 13073 : Built 1907 : NK 967 (Image)
C.J. FOWELL & CO. LTD.
No. 103 : Built 1913 : AH 5456 (Image)
JOHN FOWLER & CO. (LEEDS) LTD.
No. 7769 : Built 1898 : HC 2431 (Image)
No. 9271 : Built 1901 : AJ 5819 (Image)
No. 14910 : Built 1917 : CT 9092 (Image)
MARSHALL, SONS & CO. LTD
No. 30164 : Built 1898 : MA 7510 (Image)
No. 31022 : Built 1899 ; DE 2506 (Image)
No. 73290 : Built 1920 : BE 9749 (Image)
No. 82506 : Built 1927 : SW 2847 (Image)
JOHN & HENRY McLAREN LTD.
No. 551 : Built 1894 : AH5507 (Image)
No. 1534 : Built : 1917 : NI 1754 (Image)
RANSOMES SIMS & JEFFERIES LTD.
No. 15609 : Built 1904 : CJ 4220 (Image)
No. 19494 : Built 1907 : MI5466 (Image)
No. 26727 : Built 1914 : CI 943 (Image)
WALLIS & STEEVENS LTD.
No. 7227 : Built 1911 : HR 3577 (Image)
No. 7293 : Built 1913 : BH 6808 (Image)
No. 7683 : Built 1919 : BL795 (Image)