Farm Tractors. Michael Williams
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The cost of developing a brand-new engine can be high; when the Hart-Parr company decided to add a new 50 HP model to its list of tractors in 1927, it found an ingenious way to avoid the outlay of a new engine. Instead of developing a new 50 HP power unit, it mounted two of its existing 24 HP engines side by side to produce the new 28-50 model.
The Deering and McCormick companies were both actively developing export sales to Europe by the end of the nineteenth century; in 1901, their self-propelled mowers competed on level terms in an official test in a field near Paris. Both apparently performed well, with the McCormick Auto-Mower working at a steady 8 km/h (5 mph). A report by the judges also commented favorably on the fact that it was easy to remove the engine from the Deering machine and use it as a stationary power unit. This seems a somewhat odd comment, as it would have been more convenient to have been able to leave the engine mounted on the mower for stationary use.
One of the most ingenious but short-lived attempts to bring low-cost tractor power to smaller farms came from the Adams Husker Company of Marysville, Ohio, when it announced its Little Traction Gear model in 1909 or 1910. This was a tractor with no engine, which obviously helped to reduce the price to the farmer. It was supplied with an empty space where the engine should be, and it was aimed at those farmers who already owned a suitable slow-speed stationary engine which they could mount in the space provided.
A chain and sprocket supplied with the tractor was used to link the engine to the tractor’s transmission, supplying power to the pulley belt and by another chain drive to the rear wheels. C. H. Wendell in his Encyclopedia of American Farm Tractors says that the Little Traction Gear was available in three sizes, one designed for engines up to 9 HP, a medium-sized version for engines of 13 HP or less and the largest, which was built to accept up to 20 HP.
Hart-Parr’s big 28-50 had the same offset driving position featured on its H12-28. Production of the 28-50 started in 1927 and continued until about 1929, when the tractor range was completely updated after four companies merged in 1929 to form the Oliver Farm Equipment Co.
The Birth of British Tractors
Britain was the first European country to experiment with tractor power, and the first tractor to be built commercially in Britain arrived in 1896. It was designed and built by Richard Hornsby and Sons of Grantham, Lincolnshire, and its full official name was the Hornsby-Akroyd Patent Safety Oil Traction Engine. The makers promised four versions of the tractor powered by engines with 16, 20, 25 and 32 HP output, but it is unlikely that all of these were built. The engine was a semi-diesel based on a Stuart and Binney design, built by Hornsby under a license agreement. The layout was horizontal, and it was started by using a blow lamp and ran on paraffin with the power delivered through a transmission with three forward gears and one reverse.
Although the Hornsby tractor was designed like a traction engine for stationary work, it was also suitable for heavy haulage jobs on farms or on public roads, as indicated by the extremely strong chassis and three-speed gearbox. The sales leaflet emphasized the tractor’s haulage capabilities, suggesting that the 16 HP model would handle a 20.3- to 25.4-tonne (20- to 25-ton) load on level ground. The 32 HP model was claimed to be suitable for loads weighing up to 50.8 tonnes (50 tons).
When the new tractor was demonstrated before the machinery awards judges at the 1897 Royal Show, they were favorably impressed by its maneuverability and its ability to cope with the test circuit that included driving over railway sleepers and crossing soft ground. They obviously compared the Hornsby against steam traction engines and included “non-liability to explode” in their list of reasons for deciding to give the new tractor a silver medal. Steam engine comparisons were also prominent in a description of the tractor published in 1896 in a leading journal, Implement and Machinery Review.
“The driver has a good deal easier time of it than in the case of a steam-engine,” said the Implement and Machinery Review’s report. “There is no fire to be frequently stoked, nor are there any water or steam gauges to be kept under supervision. Indeed, the duties are so comparatively light that one man can easily undertake the driving without any assistance, which, of course, means a considerable saving to the user.” Another feature praised in the report was the fact that the engine’s exhaust system had been “rendered silent” to avoid frightening horses.
Early versions of the Rumely OilPull tractors were noted for their large size, heavy weight and the distinctive cooling tower at the front. The tractor in the photograph is a Model H, introduced in 1919 with a 30 HP twin-cylinder engine and the familiar, but much-reduced, cooling tower.
A New Commercial Model
Prices for the Hornsby tractor started at £500 for the 16 HP model, which was supplied with a pair of carriage lamps for driving on the road, a tool kit including spanners plus a hammer and chisels, a waterproof cover, and a rear-mounted winch and a cable for pulling timber. There was also a bucket, and this was used to top up the water in the cooling system, which evaporated or leaked about 250 liters (65 gallons) during a day’s work.
A pre-heater on Rumely OilPull tractors, as seen here on a Model H tractor built between 1919 and 1924, used waste heat from the engine exhaust to raise the temperature of paraffin or kerosene fuel for easier combustion. The use of cheaper, lower-grade fuels was a major attraction.
Only one of the tractors was sold in Britain. The customer, who owned a large estate in Surrey, became the first person in Britain to buy a tractor. Another three or four of the tractors were exported to Australia, and one of these was recently brought back to its country of origin by a vintage tractor enthusiast. Richard Hornsby also entered one of its tractors in an evaluation test organized by the secretary of state for war. The British Army wanted a tractor to replace some of its steam traction engines to deal with transport work such as moving heavy guns and other equipment. There was a £1000 prize for the winning manufacturer and, more importantly, the possibility of a lucrative contract. The Hornsby tractor won the prize, but the contract was never awarded, and the company’s subsequent efforts to interest the army in a track-laying version of the tractor—years before the army decided it urgently needed tanks—also failed to win an order.
The design of the Hornsby tractors was obviously influenced by steam traction engine ideas, but other British manufacturers were designing their tractors for a wider range of jobs. This was the approach used by the Marshall company of Gainsborough, Lincolnshire, when it announced its first tractor in 1906. It weighed 4.6 tonnes (4.5 tons) and was designed mainly for export, achieving modest success in Canada against mainly US competition.
A paraffin-burning, twin-cylinder engine developing 30 HP powered the early versions of the Marshall, and the engine was water-cooled, losing 9.1 to 13.6 liters (2 to 3 gallons) each day through evaporation and what Marshall called “inevitable leakages.” Hot water from the individually jacketed engine cylinders was circulated to the top of the radiator, moving down to the bottom of the radiator as it cooled, and it was then piped to the main tank at the rear before making a return journey to the cylinders.
The OilPull brand name was designed to advertise the Rumely tractors’ ability to burn lower-grade fuel, a feature which helped to boost sales of the OilPull. This was further emphasized by the phrasing of the guarantee displayed on the side of the cooling tower of this Model H tractor.
The First Marshall
The first Marshall tractor was equipped with a pulley belt for stationary work and with a three-speed gearbox for haulage. However, when the tractor was announced, the manufacturers gained useful publicity by demonstrating its performance in a non-stop plowing marathon. The marathon lasted 24 hours and, during that time, the Marshall used 200 liters (44 gallons)