Cutting corners with a new crane concept

It is only possible to pivot (horizontally rotate) conventional harvester cranes at the crane pillar. A new type of harvester crane has an extra pivoting point on the outer boom, which makes it possible to reach behind residual trees and thus probably ease thinning work. This paper quantifies differences in harvester time consumption between a conventional crane and a pivoting outer boom (POB) crane in thinning by the use of a simulation study and a field study. Simulations were made in two mapped stands. A harvester equipped with a POB crane was used in the field study. The work of a conventional crane was performed with the same machine by not using the pivoting function. Six blocks were created with densities ranging from 1230 to 3100 trees per hectare and the tree choice was restricted. The POB crane required 4-8% less time compared to the conventional crane in the simulation study and 7-15% less in the field study. In the field study, the POB crane’s mean time consumption was significantly lower for the work elements machine movement backwards and crane out. The number of machine movements backward was significantly lower for the POB crane, and 17% more trees could be cut per machine position by the POB crane. The pivoting function was used on 29% of the cut trees. Based on the consistent results from the simulation and the field study, it is concluded that the pivoting function significantly increased productivity in thinning