Productivity and Cutting Costs of Thinning Harvesters
Authors
Kalle Kärhä
Metsäteho Oy
Esa Rönkkö
University of Helsinki
Seppo-Ilmari Gumse
TTS Institute
Abstract
High harvesting costs are the main problems in first thinnings. Machines with lower operating costs could be one potential solution for cost-efficient first thinnings. The research investigated the productivity of the four most widely used small harvesters, i.e. thinning harvesters, and their cutting costs. Data were also collected on the productivity relationships between working methods and the differences between operators. In the time studies involving thinning harvesters, the Nokka Profi and Timberjack 770 represented the larger, more expensive machines, while the Sampo-Rosenlew 1046X and Valtra Forest 120 represented the more compact, less expensive thinning harvesters.
The productivity per operating hour (E15 including delay times shorter than 15 minutes) of the thinning harvesters was found to be 5.6-10.3 m3/ E15 (stem size 50-100 dm3) in first thinnings and 9.1-12.7 m3/ E15 (100-150 m3) in second thinnings. The productivity figures of the individual machines were similar. The differences were mainly attributable to the operators. The time study showed that the differences between operators using the same machines were as great as 40%.
The cutting costs for the thinning harvesters were 7.5-14.2 US$/m3 (50-100 dm3) in first thinnings when using the Nokka/Timberjack machine group. The corresponding costs for the Sampo/Valtra machine group were 5.7 and 10.5 US$/m3. It would appear that thinning harvesters can be operated at the same productivity level of medium-sized harvesters in thinnings and, consequently, they can be run at cutting costs lower than those of medium-sized harvesters.
