Performance of a mid-sized harvester-forwarder system in integrated harvesting of sawmill, pulpwood and firewood

Fully mechanized timber harvesting systems are generally characterizedby a high operational performance being widespread and usedacross many regions. Such systems are adaptable to different levels of operationalintegration, enabling also the recovery of energy wood, but givenintegration configurations affect their performance. A production study wascarried out in a Norway spruce clear-cut aiming to investigate the performanceof a mid-sized harvester-forwarder system in general, and the effectthat fuelwood recovery from tree tops may have on its performance. Datawas collected in the field during 11 days of observation using state-ofartequipment and software. Harvester’s operations were monitored usinga digital camera. Data refined from 27.5 filmed hours that accounted for1045 felled and fully processed trees was used to model and compute itsperformance indicators. In addition, fuel consumption data was sampled inthe field. The results indicated that a delay-free cycle time consumptionwas affected by variables characterizing the tree size. The net productionrate was estimated to about 26.5 m3 ∙ h -1, being substantially affected bysupplementary tree-top processing. Forwarding operations were monitoredusing a handheld computer and a Global Positioning System unit. The delay-free cycle time consumption was affected by forwarding distance andthe amount of loaded wood, resulting in a net production rate of about 19.2m3 ∙ h-1. Under these circumstances, the forwarding performance matchedthe harvester’s outputs for an extraction distance of about 100 m, indicatingthat the supplementary processing of the tree-tops had no effect onthe system’s productive performance in the studied conditions. Most likely,it affected the harvester’s fuel consumption given its proportion of 9%in the delay-free harvester’s cycle time. The results also indicated a meanfuel consumption of about 1.7 l ∙ m-3 for the studied harvesting system