Realization of a downscaled pendulum-arm suspended forwarder

Sammanfattning: Almost all logging in Sweden is carried out by the Cut-To-Length method. The method is carried out by two machines, a harvester and a forwarder. The forwarder transports the cut logs from the forest to a landing area for further transportation. Due to the uneven ground, the operators are subjected to high amplitude vibrations and the vehicle damages the ground soil when the pressure is unevenly distributed between the vehicles wheels. In an endeavor to decrease soil damage and increase the comfort for the operator, Skogforsk in collaboration with eXtractor is developing a pendulum arm suspended forwarder, named XT28. The benefit with such a forwarder is that each pendulum arm and wheel can be controlled individually. In this project a scale model (1:5) of the XT28 was developed and realized in order to enable implementation and development of a control system for its active pendulum arm suspension. A scaled model is much easier to handle and manage when tests is going to be performed. Additionally it is much more cost efficient than working with a full-scaled model. The focus point for this project will be the pendulum arm suspension and as a final test the function of this type of suspension will be tested and examined. Apart from a few design changes the downscaled model is a good representation of the XT28 and can be used in the development of a control system. After testing, it can be said that the downscaled prototype represents the full-scaled forwarder well when it comes to test the function of the pendulum arms.