Productivity and damage analysis of the RK 450 Skogsjan

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University of New Brunswick


Wood fibre gained through thinnings provides 25% of Sweden's annual wood volume harvested. In an attempt to offset high wages for manual work, mechanized systems have been developed. The RK 450 Skogsjan, a processor unit attached to the extreme end of the boom, is one of several types of mechanized processors available for thinning in Sweden. The Skogsjan can be attached to c:my large skidder or forwarder and provides the operator with a hydraulic operated unit which can delimb, buck and pile in numerous positions about the processor's chassis. In the four studies examined, three documented and one completed by the author, productivity ranged from 9.8 m3/hr to 16.6 m3/hr, depending on numerous stand and climatic conditions. Damage to the residual trees (900--1000 stems/ha) was found to be from 10 to 15 percent, the author's study being the exception with one percent. In comparison with other thinning processors such as the Rottne and Kockum, the Skogsjan type proved to produce more wood volume per hour at a lower cost. In 1978, the cost of operating the Skogsj~n wcis 162Kr ($L~0.5)/hr, while for the Rottne it was 223Kr ($55.75)/hr and 234Kr ($58.5)/hr for the Kockumo From this study it is apparent the Skogsjan thinning system would not be feasible in Eastern Canada, at the present time, because of the poor state of most stands, expertise on thinning systems and the high cost of production per m3 in relation to the return on investment.