An Innovative Truck-Mounted Cable Yarder Capable of Positioning The Tower In Sloping Conditions

The transition from ground-based harvesting systems to cable-based timber extraction is necessary for gradients from 20% to 40%, depending on factors like surface roughness and slope length. For operating on slope up to 40%, the use of cable yarders is the most widespread production method in the Alps, particularly in countries, where cable cranes are manufactured, such as Austria, Switzerland, and Italy. In Italy, about 45% of the forests are characterized by slopes higher than 41% and considering only the Alpine Regions, they have a steep terrain rate higher than the national average. However, cable yarders need of flat landing for place them and for processing and stacking material. Sometimes, placing the machine in a flat location is not possible. The aim of the research was to design and analyse the performance of a self-propelled cable yarder capable of tackling existing forestry roads and being able to quickly install it on any slope. The base machine of the cable yarder is a small off-road truck, and the cable yarder is installed on roll-off system that permit to remove it and change the base machine or change the possible activity of the base machine (wood transport, wood chipping…). The tower is able to tilt ±50° compared to the orthogonal of the frame, guaranteeing its verticality in different working conditions. The use of this machine reduces the time needed for set-up by around 50%, enabling an increase in productivity of 20% if compared with standard cable yarders. Excellent results were also obtained in the positioning of the cable yarder on steep slopes, where the experimental tests carried out showed reduced cable crane set-up times in the face of modest earthmoving works. It was only necessary to carry out a slight levelling of the ground with a surface area of approximately 1 m2 in order to place a support of logs to support the base of the tower. This outcome guarantees the possibility of being able to work on forest stands in disadvantaged stationary situations, even by small forestry companies that do not always have the investments necessary to purchase specific machinery and expensive equipment.