Slippage and Rut Formation With Two Types of Flotation Bogie Tracks

Machines with bogie axles dominate among wheeled machines in cut-to-length harvesting systems, and it is common to equip these machines with bogie tracks to enhance mobility and mitigate soil disturbance. Flotation bogie tracks are specifically designed to reduce contact pressure and thus soil compaction and rut formation on soils of low bearing capacity. Two types of flotation bogie tracks (Olofsfors Magnum and Olofsfors CoverX) differing mainly in the shape of the track pads were assessed with regard to slippage and rut formation in a field experiment. On a forest site, an 8-wheeled forwarder with a nominal payload of 14 metric tons was driven in three configurations: with bogie tracks of either type mounted throughout as well as with bare tires as a reference. Terrain was flat, but each configuration was also tested at adverse inclinations of 10% and 20% simulated by braking the forwarder with a defined braking force from a winch. For each setting of configuration and inclination, the forwarder was driven in eight consecutive passes over the same track. Wheel and travel speeds were measured over a defined distance during travel to determine slippage, and rut depth was measured at fixed locations with a laser scanner after each pass. Observed slippage was considerably lower for the CoverX than for the Magnum track at all levels of inclination, while the difference in slippage between the CoverX track and bare tires was most pronounced at 20% inclination. Slippage was higher for the Magnum track than for bare tires at 0% and 10% inclination. Rut formation was most pronounced for bare tires at all levels of inclination. The CoverX track was found more effective in reducing rut depth than the Magnum track, especially after a higher number of machine passes. These observations support the efficacy of flotation bogie tracks in mitigating soil disturbance and suggest a marked impact of track-pad design.