Tractor Trendsetters: Farmall Super M-TA
Written by Larry Gay
Transmissions for the first farm tractors provided one forward speed and one in reverse. A second forward speed was added when tractors began to be used for field work. By the 1920s, many tractors began to feature three forward speeds. Rubber tires introduced in the fall of 1932 resulted in a demand for a faster transport speed. Soon tractors were featuring four, five, or six forward speeds. However, changing gears required using the clutch which often resulted in the tractor coming to a stop. In 1954, International Harvester introduced the Farmall Super M-TA which enabled the operator to shift to a slower speed without engaging the clutch. This made the Farmall Super M-TA a tractor trendsetter.
The "TA" portion of the tractor’s model number referred to the new transmission which IH described as a Torque-Amplifier drive. The Torque-Amplifier was a planetary-gear speed-reduction unit which was an addition to the regular 5-speed gearbox. It enabled the operator to shift from one of the regular speeds to a slower speed by pulling a lever while on-the-go without using the clutch. This resulted in a 48 percent increase in the pulling power and a 32 percent decrease in the travel speed. The operator could return to the regular speed by moving the lever in the opposite direction, again without using the clutch. The Torque-Amplifier was the first example of what is described today as a partial powershift transmission.
The Super M-TA’s five regular forward speeds ranged from 2.5 to 16.7 miles per hour and engaging the Torque-Amplifier reduced the speeds to a range of 1.7 to 11.3 miles per hour. The Torque-Amplifier could be used to increase the pulling power when the tractor hit a tough spot when plowing or to slow the tractor when pulling a PTO-driven harvesting machine that encountered a heavier area of the crop. However, it could also be used to start pulling a heavy wagon in fifth-TA and then shift to regular fifth gear after getting the load moving.
The Farmall Super M-TA was a 4-plow, 4-row cultivating tractor which was rated at 48 belt horsepower with its 4-cylinder, 264-cubic-inch International gasoline or diesel engine. The Torque-Amplifier transmission provided ten forward speeds and two in reverse. The combination of the TA transmission, the independent PTO, and the live hydraulics provided flexibility during harvesting operations. The Farmall Super M-TA offered a choice of dual front wheels, adjustable front axle, or single front wheel. Operator convenience was provided with a hydraulic shock absorber seat and double-disc brakes.
Larry Gay is the author of four tractor books published by the American Society of Agricultural and Biological Engineers, including Guide to Oliver Tractors and Guide to Ford Tractors. The four books may be obtained from ASABE by calling 800-695-2723.