Gripping Volume of a Grapple Loader that Maximizes the Productivity of Chipping Unutilized Forest Biomass

Abstract

A time study of chipping operations of unutilized forest biomass using a combination of a grapple loader and a chipper was carried out. The material to be chipped was composed mainly of 4-m-length logs that were piled up in the yarding alongside a forest road. An analysis of the relationship between the volume gripped by the grapple loader and the productivity of the chipping operation showed that productivity was maximized when the gripped material volume was 0.56 m³/cycle. Productivity decreased when the gripped volume was larger than 0.56 m³/cycle, because it could not be placed appropriately on the conveyor of the chipper and the swallowing time of the chipper was too long when the gripped material was long and the amount of material was too large. When the investigated chipping operation was performed with a gripping material volume of 0.56 m³/cycle, it was estimated that the total operation time could be significantly reduced by an average of 19％ (386 s). These results suggest that productivity may be optimized by considering the optimum gripping material volume when chipping relatively long logs.