Resumen
Aim of the study: The objective of this study was to evaluate recent technological improvements to forest bundlers: a new cutting device with shears and a mechanism which allows the bundling pressure to be changed by the driver.Area of study: eucalyptus plantations in Northern Spain.Material and Methods: Several time studies were performed in order to compare and calculate productivity depending on the machine: John Deere bundler working with the traditional chainsaw and Monra bundler equipped with the technological improvements of shears and adjustable bundling pressure.Research highlights: Significant differences were found between cutting devices (shears and chainsaw) and between the Monra working at maximum pressure and at lower pressure. Shears were shown to be a more robust and reliable cutting device, with 1.02 cutting attempts per bundle compared to 1.55 with chain saw. The use of shears made the loading more efficient as it eliminates the need to shake the residues before feeding the bundler. A great advantage of this technological improvement is that it can be incorporated into other machines and thus improve bundling efficiency.In spite of this, working at standard bundling pressure, the productivity of the Monra bundler is only 3.2 per cent higher than that of the John Deere due to the fact that in the latter bundling is faster and it produces bundles with significantly more dry mass.For the Monra bundler, the option of producing lighter bundles further reduced productivity compared to when standard weight bundles are produced. However, it would be of interest to study the effect of the machine working at various pressures in order to optimize the work system. It is possible that working at higher pressures would have advantages in terms of increasing transport efficiency.Keywords: bundler; time study; shear; cutting device; slash collection; forest biomass.