Unlikely as it seems, tractors have been built that are steered by reins like a horse rather than by a steering wheel. Why would you want to do that? It was not blind tradition, but a gave a way for a farmer with a lot of horse-drawn implements to use them with a tractor rather than replacing everything at once.
It also meant that one man could operate both tractor and implement at the same time; with a conventional tractor two men would be needed.
The earliest reins tractor currently known was the USA-based Hoke (of South Bend, Indiana) design in 1913; no further information has been found so far. It was followed by the Cole tractor in the same year, but again no info has been found so far. The Detroit tractor shown below also came out in 1913.
The LaCrosse Line Drive tractor appeared in 1915, followed by the Canadian Rein Drive in 1918.
THE DETROIT TRACTOR
Left: Advert for the Detroit Tractor: 1913
The Detroit Tractor was powered by an internal-combustion engine. It is not clear why the towing pole was so long- it may have been something to do with using unmodified horse-drawn ploughs, etc.
The Detroit Tractor Company was an overshoot of Baker & Baker of Royal Oak, Michigan. It was set up in March 1913 to build Baker tractors, but a few years later moved to Lafayette, Indiana where this machine was built. It was described as 'a line-drive tractor of the universal frame design'. Presumably 'line-drive' refers to the rein-control system, but I don't understand about the 'universal frame design'.
There is more info on the Detroit rein-guided tractor in the 5-wheel car section of the Museum.
Source: An automobile trade journal 1913
THE LACROSSE TRACTOR
Left: LaCrosse tractor with rein steering: 192?
This photograph is believed to have been taken in Wisconsin. It is definitely a LaCrosse tractor; compare the photo below.
Left: LaCrosse tractor with rein steering: 1919
This looks like the Happy Farmer Model G, introduced in 1919. Four lines were used for control, two for steering and two for start/stop. In reality the farmers were not happy, because the LaCrosse had a reputation for poor build and reliability.
The Model G was built on the same frame as the LaCrosse Model F. The only difference between them was the Model G had a four-wheel chassis, while the Model F was a three-wheel design. The Model G weighed 4,670 pounds and sold for about $1250, a great deal of money at the time.
THE FOWLER TRACTOR
Left: Fowler tractor with rein steering: 1926
This is a two-wheeled vehicle with a 32 HP water-cooled V2 engine. The pulley at bottom centre is a power take-off (PTO) that allows external machinery to be driven by a belt.
Unfortunately the photograph does not give any clue as to how the reins-steering worked. Possibly by differential braking of the two wheels.
Source: Mechanics & Handicraft Vol 5, No 9, Oct 1938
There is a Fowler in this museum in Australia. Only two were made, by John Fowler of Leeds, England, to the design of Cornelius Murnane of Sydney; they were shipped to Australia where it appears both survive.
Left: Fowler tractor: 1926
The sign says 'A Henry Parkes Historical Museum'. It appears to be in Australia, probably at Quirindi.
In this display a metal pole (not visible in this photograph) joins the tractor to a two-wheeled trolley with a seat. This trolley was sometimes called a sulky.
The thing looking rather like a hammer near the wheel is probably a hinged prop to stop the tractor tipping on its nose when the pole behind it was disconnected. (Thanks to Bernd for pointing this out) The thing sticking in the front looks like a starting handle, though it seems to be missing the actual handle bit.
THE EIMCO POWER HORSE
Left: EIMCO Power Horse tractor: 1940
The Eimco Power Horse is probably the best-known rein tractor, with a number of examples surviving and operable. It is probably the make with the most surving machines.
Albert Bonham of Salt Lake City, Utah, designed the first Eimco Power Horse in the mid-1930s. They were only produced under the Eimco Company brand name for a few years; they were then sold under the Bonham name until 1942, when they were bought out by Allis-Chalmers. The Harris Manufacturing Company then acquired the rights in 1949 and manufactured the Power Horse until 1964.
Left: EIMCO Power Horse tractor: 1940
This patent for an improved design shows both axles driven by chain from a central shaft.
This drawing from US patent 2,197,248 is dated April 1940.
Left: Drive system of the EIMCO Powerhorse tractor: 1940
According to one Power Horse restorer, the hardest part was cleaning the 23 clutches in the transmission. He said that the Power-Horse tractor has 11 clutches on each side, plus a master clutch behind the engine. This sounds like a sophisticated bit of machinery.
I thought that this diagram would give some insight into the fearsome complexity, but it does not. It is confusing because arrows are used both to represent the flow of power and the flow of information, but as far as I can make out there are only four actual clutches in the diagram, giving forward, neutral, and reverse for each side of the tractor.
Source: US patent 2,197,248 April 1940
Left: Manual for EIMCO Powerhorse tractor: 1945
Front cover of the Instruction Manual for the Eimco Power-Horse Model A-20.
This version has a seat; when it was used the driver operated the control levers directly.
Note the distinctive wheel design, also seen in the photograph above.
THE CANADIAN REIN-DRIVE TRACTOR
Left: Advert for Canadian Rein-Drive tractor: 1918
The Canadian Rein-Drive tractor was a three-wheeled design.
Canadian Rein-Drive Tractor Ltd was based in the Canadian Pacific Railway Building, Toronto, Canada. It was incorporated for $1 million in 1917.
They took out US patent 135,053 published 20 May 1919. It does not seem to be available via Google Patents.
Left: Unknown street tractor: 191?
Nothing is known about this vehicle or the picture. The tractor looks rather smaller and more compact than most of the tractors on this page. The wheels are fitted with rubber (?) blocks suitable for street rather than farm used. It is being controlled by two reins.
The placards on the side of the waggon suggest this is some sort of publicity effort. The rear placard says "United States something something" so the location is probably an American city. (note the tram at far left)
It is probably summer; straw hats are being worn.
Other rein-guided tractors included the GMC Iron Horse introduced around 1918, and a caterpillar-tracked machine built by Dick Gauld, an upland Aberdeenshire farmer.