Origin of the Row-Crop Tractor: The Farmall Regular

International Harvester's McCormick-Deering Farmall led the row crop tractor revolution

Row-crop Farmall 2

This 1916 engineering photo shows the limited-production Motor Cultivator with addition of heavy center weights in the cultivator wheels. The center weights may have been added to strengthen the wheels, but there is also evidence they were an effort to overcome the tendency of the Motor Cultivator to tip sideways on hills.||Image ID 22771 courtesy of the Wisconsin Historical Society McCormick-IH Archives.

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In the early teens of the 20th century, most tractors were still designed as prime movers for pulling tools like trailing plows, field cultivators, reapers and mowing machines.

It was generally accepted that, although tractors could ease those burdensome tasks, the farmer still needed to maintain a team of horses to handle the precision work of cultivating and planting since even the smaller and more affordable tractors of the day were plainly not suited to row crop work.

In 1915, the year International Harvester tested its first known experimental motorized cultivator, the concept of a general purpose row crop tractor had not yet gone mainstream, but it was soon put to the test.

Developing the concept

Early iterations of Harvester’s Motor Cultivator featured a tricycle design with two wheels in front and a single wheel in back for steering and power (the engine sat atop the wheel’s spindle and turned with it). Some company engineers felt sure their concept warranted further development, but difficulties related to the cultivator’s high center of gravity and minimal drawbar functionality doomed it to a short life. In 1919, even though demand for Motor Cultivators remained strong, Harvester brass decided to scrap their limited production Motor Cultivator program ... but not the concept.

By 1920, Harvester engineers were thinking about a general purpose tractor/motor cultivator that led them away from the single rear drive wheel to a live front-axle design (with chain drive from axle end to the wheels) with a transverse frame-mounted engine powering the two front wheels through a conventional differential. As before, steering was accomplished with a single wheel, still located in back, but similarly designed machines were soon built with the two drive wheels in the rear and the single steered wheel in front.

Eventually, the experimental tractor’s transversely mounted engine was replaced with a longitudinally mounted unit, which helped balance the machine and inadvertently led to development of the conventional PTO for powering driven implements. Still uncertain about which way to go, engineers continued this tractor’s development as a bidirectional machine.

Operators of bidirectional prototypes were particularly fond of the now-conventional configuration that placed a pair of drive wheels in the rear because they discovered front-mounted cultivator adjustments were then easily made with the steering wheel. By late 1921, Harvester took that nimble maneuverability one step further and linked specially designed pivoting cultivator gangs directly to the steering system, which made position adjustments while traveling down the row even more responsive. Cable-operated left- and right-steering brakes were added to facilitate sharp end-of-row turns using only the steering wheel to create what came to be known internally as the “heavy Farmall tractor.”

The heavy Farmall was approved for limited production in 1922, but the machines didn’t perform as well as hoped. The program was temporarily put on the back burner. By mid-1922, a scaled-down “light Farmall” design was ready for consideration. Within a year, 26 light Farmalls had been built. According to Harvester corporate memos, 13 of those units were involved with testing and 13 were delivered to branch houses around the country for demonstration and to gather feedback. The new tricycle-style tractors raised plenty of interest, but most farmers thought they looked “funny.” Late in 1923 a limited production run of 200 light Farmall tractors was approved for the following year, with the first shipment going out in February 1924.

By the time it was released, Harvester’s new all-purpose row crop tractor was simply dubbed the McCormick-Deering Farmall. There was no need for a model number because it was the only row crop tractor in the line-up. When the larger Farmall-30 was added later, company advertising began referring to this first row crop model as the original Farmall or regular Farmall. Today, most people refer to it simply as the Regular.

The Farmall Regular

The Regular is credited with being the first successful mass-produced row crop tractor. Its popularity changed the shape of farm tractors around the world. The features making it so popular included the cultivator gang shifting mechanism, automatic steering brakes, narrow front axle, high-clearance rear axle, rear PTO and its capability as a prime mover and stationary power unit. Although the Regular was too large and expensive to be practical on some smaller farms, it made horseless farming possible for the farmers who could afford it and put scores of thousands of horses out of work.

Weighing just under 2 tons, in a package 140 inches long, 86 inches wide and 67 inches tall, the Regular offered about 20 hp at the belt pulley and 13 at the drawbar. Under ideal conditions with standard lugged steel wheels, the machine could generate 2,700 pounds of pull, a number marketing materials employed to soothe farmers into understanding that, in addition to being a great motor cultivator, the Regular was a capable 2-plow workhorse.

The power behind the Regular’s pull came from Harvester’s 221-cubic-inch displacement, 3-3/4- by 5-inch bore and stroke, 4-cylinder liquid-cooled, overhead valve, kerosene-fueled engine. This then-modern mill featured replaceable wet-type cylinder sleeves and a forged steel crankshaft turning on a pair of high-grade, heavy-duty ball-type main bearings – one at each end. Forged steel connecting rods attached precision-machined pistons to highly polished and hardened crankshaft journals using bolted caps with replaceable (and adjustable) bronze-backed, babbitt-lined bearing inserts.

Although the Regular’s engine was equipped with a gear-driven, gear-type oil pump, this device merely pumped friction-easing fluid through passageways and into troughs that facilitated rod-bearing lubrication, while the remaining bottom-end components relied on oil splashed throughout the crankcase for lubrication. Valve-train components were drip-lubricated from small oil reservoirs located above the rocker arms under the valve cover. These troughs had to be filled manually with a few squirts from an oil can. The Regular operated without an oil filter until 1929.

The Regular’s cooling system consisted of an integral water jacket cast into the engine (block and head), a front-mounted radiator and pulley-mounted fan driven by the crankshaft. The engine water jacket’s inlet was located on the lower left side of the block, while its outlet was located on the left front of the head. The system notably lacks a water pump, relying instead on the relative density differences in hot and cold water to move coolant through the system using the thermo-siphon principle.

Harvester’s row crop chassis design was a clear deviation from then-current standard tractors (10-20 gear drive and 15-30 gear drive), which boasted a single-piece cast iron mainframe instrumental in keeping gears aligned, dust and dirt out and, according to marketing materials, reduced “destructive” vibrations. Instead, the Farmall employed a more automotive-like construction model where the front and rear axles were connected with a pair of rectangular-tube frame rails that also located the engine and clutch housing.

Power from the new row crop tractor’s engine initially was delivered to the transmission through a multiple dry-disc service clutch (foot controlled) with a single large coiled pressure spring. Within a few years, a more conventional single dry-disc clutch with 9-spring (radial arrangement) pressure plate replaced the original. The tractor’s heavy-duty sliding spur gear transmission was bolted directly to the rear axle housing, which supplied the rear mounting bosses for the tractor’s frame channels.

In the standard configuration, the Regular had three speeds forward (2, 3 and 4 mph with 40-inch-diameter drive wheels and engine speed of 1,200 rpm) and a single reverse (2.5 mph under the same conditions). The transmission’s rear output shaft doubled as the differential’s pinion shaft. Differential output was routed through a pair of countershafts whose outboard-mounted bull-pinion gears engaged a pair of axle-mounted large-diameter bull gears located in the cast iron, drop-box-style final drive housings. This final drive model is still used in some tractors built today.

A pair of internal expanding-shoe, drum-type brakes helped steer and stop the Regular throughout production. The rotating drums were affixed to the outboard ends of the bull-pinion shafts (left and right countershafts), which passed completely through the final drive housings. Brake shoes were mounted to the outboard surface of the final drive housings themselves and were lever-actuated on both sides with cables attached to the steering system. Stopping the tractor’s forward or reverse motion and holding it on a hill was accomplished with a hand lever located to the operator’s left, but that actuated only the left brake. An optional right-side hand lever was available late in 1931, but by then many farmers had designed their own solution – some even created foot-pedal controls.

Steering the early Regular was accomplished with a 4-spoke cast iron wheel mounted on the end of a horizontal steering shaft located above the tractor’s hood (a wood-rimmed steering wheel was optional partway through production). The steering shaft’s forward end was fit with a straight-cut pinion gear that engaged a larger diameter bull gear, which drove a tapered pinion engaging the fully-exposed steering sector. An enclosed (duckbill) version of this steering gear was used with the optional wide-front axle and was available as a retrofit in about 1934.

The Farmall Regular was equipped with rear PTO as standard equipment. The PTO ran in conjunction with the belt-pulley drive and could be engaged or disengaged with a lever on the left-hand side of the transmission. The PTO’s output shaft was 1-1/8 inches in diameter with six splines. When the American Society of Agricultural Engineers standardized farm tractor PTO specifications in the early 1940s, Harvester offered a kit to bring the Regular’s PTO output shaft into compliance. The belt-pulley drive was integral to the transmission and located the pulley beneath and perpendicular to the right-side frame rail. Pulleys offered for the regular-tread Farmall had a 6-1/2-inch face and were available in several diameters, which allowed speed adjustment for a variety of belt-powered equipment.

The standard drawbar used on the Regular throughout production consisted of a U-shaped bar mounted horizontally (U’s legs facing forward) on trunions attached to the final drive housings. The drawbar extended fully between the left and right final drives and offered a number of evenly spaced holes for multiple hitch offsets. The drawbar was further supported with a pair of round-rod stay bars hooked into one of a series of holes in the final drive housings, limiting its vertical movement and offering some level of height adjustment.

Optional equipment for the Regular included too many steel wheel styles and combinations to list, swinging and side-hill drawbars and non-adjustable wide-front axle, to name a few. The tractor was also available in a narrow-tread design and specially fitted Fairway variants were put together for estate maintenance and the golf industry.

Harvester produced more than 134,000 Regulars from 1924 to 1932. In 1930 the Farmall listed for $825.

Row crop revolution

It may have looked funny when first tested on the market, but the Farmall concept caught on like wildfire. At the time, Harvester management was so impressed with the Regular’s sales numbers that they revitalized the entire Farmall program, which gave birth to the 3-plow F-30 in July 1931 and set the stage for generations of Farmall tractors to come. The Regular was replaced in early 1932 with an updated version called the F-20, and an even lighter, more accessible Farmall came on the scene in 1933 as the F-12.

Once the Regular hit the market, virtually all other manufacturers scrambled to develop their own designs. John Deere had its converted GP Tricycle ready for market in 1928, while Oliver Hart-Parr followed in 1930 with the row crop 18-27. Allis-Chalmers and Minneapolis-Moline got into the game the same year with their respective tricycle models, UC All-Crop and Universal MT. By the mid-1930s, the tractor market was fully steeped in the Regular’s narrow-front, high-clearance row crop design, which remains today the most recognizable farm tractor symbol in history. FC 

Oscar “Hank” Will III is an old-iron collector and the editor of Grit magazine. Contact him at hwill@ogdenpubs.com