A New Approach To Derive A Productivity Model for the Harvester “Valmet 911 Snake”

Productivity models are important decision support tools for harvesting operations. They should be derived with the least possible effort but with the highest possible precision. Models based on production monitoring or time studies are time consuming in their derivation. No models are available for new machine developments although it is particularly important to estimate productivity under given conditions and make statements about parameters such as climbing limits on steep terrain. The Valmet 911 Snake is a tracked harvester that has been specially developed for harvesting operations on steep terrain. A standard four-wheeled Valmet harvester serves as a carrier platform whereby the four wheel sets are replaced with trapezoidal tracked undercarriages. This construction results in better traction, reduced impact to the ground and greater climbing possibilities on slopes. For the productivity model derivation a combined approach has been used. The model consists of three parts: tree processing model, locomotion model and delay model. The delay model has been chosen from literature, the tree processing and locomotion model have been derived from empirical studies. The productivity potential and climbing capabilities of the Valmet 911 Snake steep terrain harvester up to an inclination of 70% could be verified.