The Benefits of Tridem Axle Groups for Log Truck Application

The use of tridem axle groups for heavy commercial trailers was spawned by the Roads and Transportation Association of Canada (RTAC) research of the 1980s and is now commonplace on semi-trailers and B-trains in Canada. The Western Canadian log transportation sector employs a number of industry-specific configurations that are fundamentally different in design and operation to those studied in the RTAC research. Over the last decade, this sector has met the challenge to improve productivity by adding more axles to the trailing system of the traditional 5-axle tractor/pole trailer combination. Although productivity gains were realized with the addition of more trailing axles, both dynamic performance and vehicle mobility were reduced. Where tridem axle groups are used as an alternative to the multi-articulated three and four axle trailer assemblies, dynamic stability is improved and where tridem drive axle groups are used, mobility is also improved. This paper describes the research results from a number of tridem-related projects undertaken by the Forest Engineering Research Institute of Canada.