Making Tracks with Crawler Tractors

Tractor expert Bob Pripps traces the evolution of crawler tractor steering systems.

| May 2016

  • The tricycle Minnis steam crawler was demonstrated in 1869 and, by all accounts, worked very well. Apparently, material shortcomings prevented further development and only one was built.
    Image courtesy Robert N. Pripps
  • Prior to the development of crawler tracks, extensions were fitted to this 1889 Best steam tractor’s wheels to increase flotation in soft soil. It was an inadequate solution, as shown in this photo, where the machine is mired and the crew is working to extricate it.
    Image courtesy Robert N. Pripps
  • A circa-1902 Best steam engine teamed with a Holt steam engine, pulling log wagons. These powerful steam traction engines found work in timber harvesting prior to the development of crawler tracks.
    Image courtesy Robert N. Pripps
  • The Holt No. 122 was the first conversion by Holt from wheels to tracks. This 1908 crawler was rated at 50 hp and had a steam cylinder for each track and steam power steering of the tiller wheel.
    Image courtesy Robert N. Pripps
  • A cutaway view of Best’s popular 75 Tracklayer of 1913. Best used the name “Tracklayer” to counter Holt’s Caterpillar trademark. The Model 75 used differential and brake steering along with the tiller front wheel.
    Image courtesy Robert N. Pripps
  • Production of the Holt Model 75 began in Stockton in 1913 (and in Peoria in 1914) and ended in 1924. This is a 1920 model.
    Image courtesy Robert N. Pripps
  • A 45 hp Holt Caterpillar pulls two 3-bottom John Deere plows in a 1916 plowing demonstration.
    Image courtesy Robert N. Pripps
  • Designed especially for Midwest farmers, the Peoria-built Holt 45 was made with a wide-front tiller arrangement. This one (a 1920 model) provides belt power to a corn chopper.
    Image courtesy Robert N. Pripps
  • This dramatic photo (taken in the 1930s) shows a real challenge for both the Caterpillar R4 crawler and the Holt combine to work on such a side hill.
    Image courtesy Robert N. Pripps
  • Trackson Co., Milwaukee, made a name for itself with crawler conversions for the then-popular Fordson tractor. It soon determined that the same arrangement could be made for other wheel tractors such as this 1930 Case Model C. For the conversion, rear track sprockets replaced the drive wheels and large brake drums were added. Brake shoes contracted on the drums activated by linkage from the steering wheel, causing the tractor to turn. McCormick-Deering 10-20s were also converted.
    Image courtesy Robert N. Pripps
  • Deere & Co. delivered wheel-less and differential-less Model B orchard tractors like this 1946 BO Lindeman crawler to Lindeman Bros., Yakima, Wash., for conversion to crawler tracks. These conversions employed lever-actuated clutch-brake steering. No foot brakes were provided. These machines were popular in the hilly orchards of Washington. Deere eventually bought the Lindeman operation and continued making crawlers in-house.
    Image courtesy Robert N. Pripps
  • This rubber-track Challenger uses hydrostatically biased differential steering controlled by the steering wheel, so driving is done in much the same way as a wheel tractor. This 1991 Caterpillar Challenger 65B has a 285 hp diesel, a full power-shift 10-speed transmission and weighs about 35,000 pounds. It has a transport speed of 18 mph. Caterpillar sold the Challenger brand to AGCO in 2002.
    Image courtesy Robert N. Pripps
  • This nicely restored 1980 John Deere 450E uses a 60 hp 4-cylinder engine and a 4-speed transmission with a 2-speed power-shift auxiliary and a shuttle-shift reverse. Steering is by clutch-brake with hand levers.
    Image courtesy Robert N. Pripps
  • The latest technology from Cat, this 2016 Caterpillar D7E transmits power from the engine to the tracks electrically. Steering is done by varying the speed of the track drive engines.
    Image courtesy Robert N. Pripps
  • “Like sitting in a second-story window, driving a house” was the reaction of these visitors viewing a 1993 Caterpillar D11N. The group – members of the Antique Caterpillar Machinery Owners Club (ACMOC) – toured the Caterpillar plant in 1993. Current production versions of the D11N use an 850 hp engine and weigh 230,000 pounds.
    Image courtesy Robert N. Pripps

A lot of antique farm tractor buffs have never driven a crawler tractor and may not have considered the unique difficulties in steering these machines, or how steering systems have evolved since the first crawlers crawled. It is generally understood that crawlers are controlled by a pair of steering levers (in some cases, a “T” handle, or even a steering wheel), but most people don’t bother with what happens beyond that.

Crawler tractors were born of necessity at the turn of the 20th century in the rich, but boggy, farm lands of the Sacramento, California, River delta. Gigantic wheat farms required big, heavy, steam tractors and combines, both of which were made by the competing Holt and Best manufacturing companies. These big-wheeled monsters frequently sank in the bog, and when they did, there was nothing available to pull them out. 

As early as 1858, a successful steam-powered traction engine with crawler tracks had been demonstrated by inventor Warren Miller in nearby Marysville, California. The tracks provided the necessary flotation and traction to work on the soft land. Apparently Miller built only one machine, but others followed, including units by Minnis (1869), Parvin (1871), Stratton (1893) and Lombard (1900).

These machines all used individual steam cylinders for each track; consequently, a differential between the tracks was not required. Steering was accomplished by means of a front tiller wheel. In the case of the Minnis, the tiller was a track also powered by a separate steam cylinder. The Lombard (used exclusively in the north woods for winter log hauling) used skis reminiscent of those on today’s snowmobiles.



Solving the gas engine challenge

By the early 1900s, both the Best and Holt companies were converting their steam traction engines to crawler tracks. Both soon saw the advantage of internal combustion gasoline engines and each developed their own. Holt and Best continued that vigorous competition until 1925, when they merged to form Caterpillar.

When going to the gasoline engine, the problem of delivering power to the tracks became more complicated. The tiller wheel did not have enough authority to overcome the tendency of the tracks to continue in a straight line. Holt solved this problem on its 1907 gasoline-powered crawler by including steering clutches in the drive for each track. By disengaging drive power from the “inside” track, the tiller wheel could then negotiate the turn. Holt did not add track brakes to assist in steering until 1918. The tiller wheel was controlled by a conventional steering wheel at the operator station through a series of shafts, universal joints and a worm-sector gear. 



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