Analysis of a double steering forest trailer for long wood log transportation

A cost effective technical solution of a forest double steering trailer was studied and tested, allowing decrease of radius of curvature and increase of the maneuverability, independently from the length of the transported logs. The steering system improves the so called “stingertype truck” configuration using an articulated frame; through a rearward hinge, the front wheels direction mechanically controls and adapts the direction of rear twin wheels. The study was based on CAD simulations considering the dimensions of the trailer transporting logs with a length up to 12 m. For different log lengths the simulation analyzed the total maneuver area, in terms of minimum curve radius and curve widening. A field test on a prototype operated for transport of long logs along a representative forest road in the Alps was carried out. The results confirm the improvements foreseen by CAD simulations, with allowed curve radius down to 6 m, even with 12 m logs.