TracTracTor Tradition

Enlarge Image Image Gallery The T-20 TracTracTor, Harvester’s first complete crawler tractor design, proved both popular and reliable. This 1937 model belongs to Jason Sweeter.

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Modern crawlers are so universally associated with dozer blades and dirt work that it's hard to imagine that their fundamental design was born of a prime-moving need for more flotation and traction on the farm. Indeed, when Holt Mfg. Co. released the first successful gasoline-powered crawler in 1908, the tractor was designed specifically to work California's rich Sacramento River delta, and its duties were all about pull. Although this tractor had some reliability difficulties, its successes were significant enough to net Holt nearly 200 competitors within less than a decade. When the dust from bankruptcies and consolidation settled in 1920, only about 10 manufacturers remained in business. By decade's end, that number was halved, which made room for one more player - International Harvester Co.

Exactly why IH didn't claim a share of the tracklayer market early on is anyone's guess, but most Harvester historians point to complex patent issues relating to crawler undercarriage design, and the company's intense focus on wheeled tractors. Market size also played a role in the decision-making process, since crawler tractor production rarely amounted to more than 10 percent of wheeled tractor counterparts. However, International Harvester engineers were well aware of advantages associated with endless-track drive systems long before the company entered the crawler market, and had worked with them as early as 1916 or 1917.

A slow crawl

Early IH documents point to an experimental drive-train program centered on the 4-cylinder International 8-16 wheeled tractor (not to be confused with the 1-cylinder 8-16 Mogul), which included skid-steer-style four-wheel and six-wheel drive variants along with a pair of tracklayers. At least two experimental 8-16 crawlers were built in the late teens. One was a half-track concept steered with front wheels; the other had full tracks and steering clutches. In these experimental designs, Harvester's track was notably light-duty and the 8-16 project was never developed further, but tracks appeared on other experimental machines in upcoming years.

Crawler tractor development at IH ground to a halt in the early 1920s, but that didn't deter allied equipment companies from taking a stab at it. By 1924, several approved manufacturers offered track kits to fit Harvester's McCormick-Deering 10-20 and 15-30 standard tread tractors. For example, Hadfield-Penfield Steel Co. offered the Alwatrac full crawler attachment for the 10-20 that included the necessary steering system in addition to the undercarriage, while Moon Track of Los Angeles and San Diego offered a half-track attachment that replaced the tractor's rear drive wheels with a pair of crawlers, leaving the front wheels to handle directional changes. Tracklayer conversions could also be obtained from Mandt-Freil, Trackson and others.

Encouraged by the successes its tractors achieved with aftermarket crawler makers, Harvester engineers pursued their own conversion design and announced the McCormick-Deering 10-20 and 15-30 Track Layers in mid-1928. These machines offered 10 and 15 respective drawbar horsepower and are extremely rare today (particularly the 15-30 version). Most so-called Track Layers appear to have been prototypes for the 10-20 (and possibly 15-30) TracTracTor (note the name change), which entered regular production on Oct. 1, 1928. Little documentation exists for the 15-30 TracTracTor beyond 1929, but the 10-20 version proved popular enough to survive.

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