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

Abstract

Fully mechanized timber harvesting systems are generally characterized by a high operational performance being widespread and used across many regions. Such systems are adaptable to different levels of operational integration, enabling also the recovery of energy wood, but given integration configurations affect their performance. A production study was carried out in a Norway spruce clear-cut aiming to investigate the performance of a mid-sized harvester-forwarder system in general, and the effect that fuelwood recovery from tree tops may have on its performance. Data was collected in the field during 11 days of observation using state-of-art equipment and software. Harvester’s operations were monitored using a digital camera. Data refined from 27.5 filmed hours that accounted for 1045 felled and fully processed trees was used to model and compute its performance indicators. In addition, fuel consumption data was sampled in the field. The results indicated that a delay-free cycle time consumption was affected by variables characterizing the tree size. The net production rate was estimated to about 26.5 m3 ∙ h-1, being substantially affected by supplementary tree-top processing. Forwarding operations were monitored using a handheld computer and a Global Positioning System unit. The delay-free cycle time consumption was affected by forwarding distance and the amount of loaded wood, resulting in a net production rate of about 19.2 m3 ∙ h-1. Under these circumstances, the forwarding performance matched the harvester’s outputs for an extraction distance of about 100 m, indicating that the supplementary processing of the tree-tops had no effect on the 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 mean fuel consumption of about 1.7 l ∙ m-3 for the studied harvesting system.