Development of a Modulating Viscous Fan Drive for Agricultural Tractors

Attempts to improve fuel efficiency of farm tractors motivated the development and application of viscous fan drives to agricultural tractors. Early drives on tractors performed in an on-off fashion similar to drives widely used in on-highway trucks and passenger cars. Due to the high engine power and slow moving operational modes of farm equipment, a drive which continuously modulated output speed as a function of cooling requirements was desired. A design was generated and applied to agricultural tractors. Resulting vehicle performance improvements include reduced fuel consumption, reduced operational noise, and reduced engine warm-up time.