Chris Heer of the Heer Engine Co. in Portsmouth, Ohio joined with Morton in 1910 to form the Morton-Heer Co. in Portsmouth to build a 4 Wheel Drivetractor designed by Heer. The 4WD , 4-wheel-steering, tractor with equal-sized front and rear wheels, center-pivot steering, worm-drive axles, and a Heer horizontally-opposed 2-cylinder engine was the first 4WD tractor on the market when it was introduced in 1912 (Heer received a patent on it in 1915). The Heer Engine Co. soon absorbed Morton-Heer and the Morton-Heer tractor became the Heer. The Heer company was reorganised into the Reliable Tractor and Engine Co. in 1915 or 1916. The new company manufactured the Reliable 10-20 2WD tractor until 1921. The same tractor was sold by Fairbanks, Morse & Co. as the Fair-Mor tractor.
By 1912 the Morton Tractor Co. of Harrisburg, Pennsylvania, renamed the Morton Truck & Tractor Co., had developed a Morton 4WD tractor with some design features in common with the Heer tractor. By 1920 the Harrisburg Morton company had been replaced by the Pennsylvania Tractor Co. of Philadelphia, which produced the 4-cylinder engined Morton Four-Wheel Drive 40 and the 6-cylinder engined Morton Four-Wheel Drive 60 rated at 60HP.
- List of Tractor Manufacturers
- List of Types of Agricultural Machinery
- List of Engine Manufacturers
- Gray, R.B. (1954). The Agricultural Tractor: 1855-1950. American Society of Agricultural Engineers.
- Wendel, C.H. (1992). Encyclopedia of American Farm Tractors. Motorbooks International, Osceola, Wisconsin.
- Wendel, C.H. (2000). Standard Catalog of Farm Tractors, 1890-1960. Krause Publications, Iola, Wisconsin.
- Wendel, C.H. (2005). Standard Catalog of Farm Tractors, 1890-1980, 2nd Ed. Krause Publications, Iola, Wisconsin.
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