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Written By Larry Gay
During the 1950s, farmers were increasing the size of their operations and asking for tractors with more power. Tractor engineers answered their requests by designing engines with a larger displacement, increased engine speed, or a combination of both. Most tractor models during this era offered a choice of gasoline, LP-gas, or diesel engines, but the diesel engine generally had to have a larger displacement than the spark-ignition engines to provide a similar power output.
The new-for-1962 Allis-Chalmers D19 tractor took a different approach for obtaining increased horsepower in its diesel engine by being the first farm tractor with a factory-installed turbocharger. The turbocharger enabled Allis-Chalmers to use the same 262-cubic-inch size of 6-cylinder Allis-Chalmers engine for all three fuel types and obtain similar power outputs. Using the increased displacement technique for its diesel engine would have required a 280- to 300-cubic-inch diesel engine to match the power from the 262-cubic-inch gasoline engine.
A turbocharger consists of two high-speed turbines on one shaft. One turbine is mounted in the stream of the exhaust gases which drives the turbines. The other turbine is located in the intake air stream and forces more air into the cylinders than would a naturally aspirated engine. The increased quantity of air permits more fuel to be injected into the cylinders which increases the power output of the engine.
The Allis-Chalmers D19 was initially rated as a 5-plow tractor with 70 PTO horsepower. At the Nebraska tests in April 1962, the D19 with its gasoline engine produced 71.5 PTO horsepower, the LP-gas version was measured at 66.2 PTO horsepower, and the D19 with its turbocharged diesel engine developed 66.9 PTO horsepower. A 3-position hand lever provided a high and low speed in each of four gears for eight forward speeds. The neutral position between the high and low positions stopped the forward travel, but not the PTO. The foot clutch stopped all power.
Initially turbochargers were used to provide more power for the larger models of tractors. Soon this expanded to one size of diesel engine providing three levels of power by being naturally aspirated, turbocharged, and turbocharged and intercooled. Today this technique is being used for all sizes of diesel engines, including those in utility tractors.
Larry Gay is the author of four tractor books and the ”Machinery Milestones” articles in Heritage Iron magazine. To learn more about this magazine which focuses on the 1960-1985 era, go to heritageiron.com or call 1-800-552-6085.
I have a question. I reciently discovered a JD BO (B Orchard) newly restored for sale. What price would I expect to pay? Looks cherry.