The Allis-Chalmers Manufacturing Co. was formed on April 16th 1913 with Otto Falk as its president, and it was he who was largely responsible for the introduction of farm equipment to the A-C product line. The first step in this direction was an agreement to build under license a self-propelled rotary cultivator developed by Motoculture Ltd of Basel, Switzerland. Such designs were quite popular in Europe at the time, but Allis-Chalmers was unable to persuade the American farmer of their benefits. The second venture undertaken by Falk was the construction of a tractor-truck, which was equally at home in the field and on the road. This half-track design, which appeared around 1915, was unfortunately ahead of its time and priced too high, although a batch of ten was sold to Russia. At least one of these was fitted with armour-plating and a gun, and participated in the Russian Revolution and subsequent civil war.

At the same time Allis-Chalmers was also developing its first true tractor, the three-wheeled 10-18 model, a prototype of which was completed by November 1914. This was heavily influenced by the best-selling Little Bull tractor of the same period - in fact, Falk had already been approached by the Bull company with a proposal for co-production, but had declined in favour of Allis producing their own design. Serial production of the 10-18 began the following year, but it never matched the success of the Bull, as the design was already becoming outdated and farmers were looking towards more conventional four-wheel designs. In spite of this. Allis pushed ahead with their plans for a successor to the 10-18, the little 6-12 model, a lightweight machine based this time on the "Universal" tractor produced by the Universal Tractor Co. of Columbus, Ohio. (It was so similar in fact, that when Moline took over the Universal Co. in they successfully sued A-C for copying the design.) The 6-12 proved to be another commercial failure though, and even the novel idea of joining two 6-12s back to back to double the power, was not enough to tempt farmers, especially as the Fordson was already begininng to make its presence felt.

Allis's response to this was the 15-30 model, its first conventional four-wheeled tractor, and also the first to use its own design of four-cylinder engine. Introduced in 1918, the horsepower rating proved too conservative, and the uprated 18-30 that appeared the following year was the first of the highly successful Model E series. Special versions of the Model E with more powerful engines and various extras were also offered to try and tempt threshing crews away from steam power. The introduction of testing at Nebraska saw the 18-30 evolve further into the 20-35 model, and when this tractor was given a thorough re-design in 1927 by Harry Merritt and the price was also cut significantly, sales went from strength to strength. Less sucessful though was the smaller 15-25 Model L, which had been introduced in 1921 with a 12-20 hp rating, and was aimed at farmers who perhaps did not need the extra power of the Model E. This tractor was entering an already overcrowded marketplace, however, and sales of the Model L were low, although at least one tractor made it as far as Australia!

In the late 1920s, Allis made another attempt at building a smaller tractor, this time with far more success. The Model U, which appeared in 1929, was the first tractor to feature Allis's new Persian Orange colour scheme, another of Harry Merritt's initiatives. It was also one of the first tractors to use pneumatic tyres. The purchase of the Monarch company in 1928 allowed A-C to break into the crawler market, and it also diversified into harvesting equipment in the 1930s. It was the Model U and its successors that really put Allis-Chalmers on the map as far as tractor production was concerned though, and A-C went on to become one of the world's largest producers of tractors, with factories in Europe and Australia. In fact, the distinctive orange tractors continued to be built until 1985, when the company was purchased by Germany's Klockner-Humboldt-Deutz, which in turn became part of the giant AGCO Corporation in 1990.

Model 6-12     (1919-1926)
The little 6-12 appeared in 1919 and in common with several other similar machines of that era, it was powered by a four-cylinder LeRoi Model 2C petrol engine of 3.125 x 4.5 in bore and stroke running at 1000 rpm (and later 1200 rpm). It had a single forward and reverse speed and was fitted with a Kingston Model L carburetor and either an Eisemann or Splitdorf (Dixie) magneto. The tractor was articulated just behind the rear axle and the single rear "sulky" wheel (later replace with two wheels) could be substituted with a range of implements, including existing horse-drawn ones. In illustrations it was often paired with an Oliver single-furrow plough. A total of 1471 A-C 6-12 tractors were built between 1919 and 1926, with serial numbers starting from 10001. A special Model B orchard version of the 6-12 with lowered engine and covered wheels appeared in 1920, and an industrial version with heavier flat-spoked wheels also appeared. However, the most unusual modification was the so-called "Duplex" model, which consisted of two 6-12s joined together back to back - this doubled the power and gave four-wheel drive, supposedly allowing a three-furrow plough to be used, but it does not seem to have been very successful.

Model E 15-30/18-30     (1918-1921)
Allis introduced their first conventional tractor, the 15-30, in 1918. It used their own make of engine, a four-cylinder 4.75 x 6.5 in OHV unit that ran at 830rpm. Two forward speeds were provided. The tractor had a sheet-metal radiator and the engine compartment was enclosed by steel panels on the very first tractors, although roll-down canvas curtains also made an appearance. In 1919, after extensive field testing, the tractor was remaned the 18-30 and the Model E designation also began to appear. Among the cosmetic changes on the uprated model was the replacement of the old radiator with a cast iron one that had raised "Allis-Chalmers" lettering on the header tank, and flat-spoke front wheels also seemed to appear around this time. Near the end of production the engine speed was increased to 930 rpm. Both the 15-30 and 18-30 were designed to burn kerosene (after starting on petrol) thanks to a special vaporizer on the manifold and a double-bowl Kingston Model E carburettor, although the latter was replaced with a Model L on later tractors that ran on petrol alone. K-W and Dixie Model 46 magnetos were used at first, but these seem to have given way to an Eisemann Model GS4 on later examples of the 18-30. A total of 1160 Model 15-30 and 18-30 tractors were built, with serial numbers starting from 5000.