Incidence of trailer frame structure on driver's safety during log transportation

The frame structure of the trailer may influence both the traction and the tractor-trailer stability, especially along sloped paths. The aim of this research was to analyze a trailer overturning and the strains on the connected tractors (wheeled, or crawled) during log transportation (loose or tied) along a hillside. Two two-axle trailers were used: tandem and turntable steering. Three types of measurements were carried out during the field tests: (i) the detachment from the ground of the rear upstream wheels (or crawler); (ii) the transversal and longitudinal strains occurring when the trailer overturned (and released the hooking system of the tractor); (iii) the lateral deviation of the rear wheels (or crawler) of the tractor. The study highlighted that the two-axle trailer with turntable steering combined with the crawl tractor gave better results in terms of safety during trailer overturning. In addition, independent of the type of trailer, a tied load was found to be more dangerous than a load restrained only by steel struts, because when overturning, the load forms a single unit with the trailer mass which increases the strains.