STEERING EVALUATIONS OF A TRIDEM DRIVE TRACTOR IN COMBINATION WITH POLE TRAILERS

Over the last decade, the log transportation sector of the forest industry in western Canada has improved productivity by adding more axles to the trailing system of traditional 5-axle configurations, to the detriment of vehicle mobility. However, if payload capacity is increased by adding a drive axle to a tandem drive group, the resulting tridem drive system will provide both productivity and traction benefits. Unfortunately, adding the third driven axle to the drive group of the tractor changes the handling performance of the vehicle, specifically the steering response during low speed, tight turns. To determine the tridem tractor's steering response, a testing program was undertaken to validate computer simulation models; these models were then used to determine the appropriate vehicle parameters to ensure acceptable handling on both high and low friction surfaces. Recommendations for vehicle parameters are presented in terms of the respective weights and dimensions regulations for the provinces of British Columbia and Alberta. (a) For the covering entry of this conference, please see IRRD 895232.