With two newly developed forwarder prototypes, five new and different modules were implemented and tested in the fields under varying production conditions within Europe. These modules are developed towards raising the productivity of the machine, improving the working conditions and lowering the ecological impact of the forwarding process. The modules contain a hydrostatic-mechanical transmission system (HVT, M1), a suspended cabin (M2), an energy regenerating and recuperating hydraulic crane (M3), a triple bogie axle for wet terrain, that can be used with or without tracks (M4) and a monitoring system to surveil and document the machine status to derive further information of production and environment (M5).
With the tests of prototype machines, the aims of development could be proven by the field tests, that were executed within the study. Especially the effect on the soils on sensitive areas, also without the use of bogie tracks, as it was tested on distributed bark beetle infested stands in Saxony, was one field of application where the advantages of tire-based working, longer bogie axle and high contact surface were positively assessed. With more experiences, the revelation of further advantages or limitations are expected.
Within the field tests, all modules of the “Triple Bogie Prototype” (M3, M4, M5) were assessed with a positive effect. For wetland (Saxony) or even peatland working conditions (Scotland, Lithuania), the triple bogie showed advantages in technical accessibility but also the lower environmental impact on sensitive areas. Without the use of tracks, especially under varying, partly sensitive soil conditions the system has advantages towards other systems as the machine was able to relocate itself on own axle for long distances and provide the protection effect. The protection of ditches while entering forest stands was a positive additional effect of the system that could be observed as it acts like a built- in bridge. Due to potential high load capacity of both base machines, also a high productivity was recorded that fit or exceeded literature findings. The crane system (M3) which has also a high positive influence on the fuel consumption could withstand a fuel consumption reduction effect on its own, at is was proven under laboratory conditions.
- With higher productivity, now due to higher driving speeds and in course of a lowered fuel consumption, the second, “HVT- Prototype” (M1, M2, M5) setup presented its advantages especially under longer hauling distances with high possible driving speeds. This machine can be especially be efficiently used in regions with low road densities.
- With the monitoring system (M5), the environmental impact and the machine behavior was actively observed and evaluated. As the here implemented iFOS system is freely configurable, it was successfully implemented in the project and could for instance be further introduced as modular environmental documentation system by forest enterprises or in public services. The separately developed data-based crane scale as stand-alone or industry 4.0 service, makes it possible to use the forwarding information in logistic applications like the energy wood supply in the wood chip logistic (Geiger et al. 2019).
