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Volker Wittig

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Agricultural Engineering


A new method of predicting the drawbar pull developed by agricultural tractors was designed and evaluated. A single wheel tester, similar to a rear tire of a tractor, was used to establish topsoil traction conditions by loading it with known loads and measuring the maximum transferable torque. This resulted in a linear relationship between torque and wheel load. The slope of this line represents, therefore, a certain topsoil condition. When used with the soil parameters bulk density and moisture content, the prediction of tractor coefficient of traction in relation to wheel slip was shown to be more accurate than the standard Wismer and Luth equation recommended by ASAE (ASAE, 1988).

Library of Congress Subject Headings

Tractors -- Tires
Traction-Engines -- Performance
Soil physics



Number of Pages



South Dakota State University