The authors are:
Tim Harrigan, Ast. Professor, Agricultural Engineering, Michigan State University; Richard Roosenberg, Exec. Director; Dulcy Perkins, Project Coordinator, and John Sarge, Shop Coordinator,
Tillers International, Kalamazoo, Michigan
Measurements of draft as tension (pounds-force, lbf) in the towing chain were made while pulling wagons over a range of tractive surfaces. Wagon draft ranged from about 4% of GVW with pneumatic tires on a gravel road to 16% of GVW when using steel tires on firm soil. Compared to pneumatic tires, the use of steel tires increased draft 50% to 100%. The use of wider or taller tires increased bearing area, improved flotation in soft soils and reduced draft. ...