Poje Anton, MSc.

A study was conducted on chip production from logging residue left after a cable yarder operation.
The logistics were managed with tractor and trailer units (shuttles). The study specifically
dealt with a very difficult case of space constrained operations, further expanding the
knowledge about chip supply in extreme work conditions. The focus of the investigation was
also extended to the shuttles. The study tested a production chain, in which only 3 machines
(1 chipper, 2 shuttles) were used to minimize operational costs. The use of 2 shuttles was decisive,
reducing shuttle delays. The chips produced had an average moisture content of 40.2 ±3.1%.
Particle size distribution shows an unfavorable composition. The content of accepts is as low
as 72%, while oversized particles get up to 5.4% and fines rise to a maximum of 24%. The
estimated net productivity of the whole system was 11.5 t PMH-1, corresponding to a gross
productivity of 11.1 t SMH-1. The cost of the whole operation amounted to 21.2 €t-1.

In recent decades fully mechanised cut-to-length forest harvesting systems have spread from
flat and gentle to steep and rough terrain. To analyse the potential adverse impact of these
changes on operator health, an observational study of exposure to noise and whole-body vibration
(WBV) was carried out in karst terrain. The results showed that, in contrast to exposure
to noise, the exposure of harvester and forwarder operators to WBV exceeds the daily exposure
action value specified in the European Directive. Differences between work sites may contribute
up to 8.7 dB(A) to noise exposure and up to 0.28 m/s2 and 6.0 m/s1.75 to WBV exposure
when working with forwarders and harvesters. Aside from technical upgrades of machines,
reduction of exposure to both WBV and noise, while simultaneously maintaining high productivity,
requires careful selection of work sites and adapted work organisation.