Timber Concentration Trials by Two Skyline Types in a Turkey Oak Coppice Forest

Rom

1986

11 S.

8 Abb., 4 Tab., 4 Lit. Ang.

Bandaufführung

11832

96985

In harvesting trials of a Turkey oak coppice forest at Melitani di Cerva, Catanzaro (Calabria), timber concentration from the stump to the skid was performed by two different types of skyline, i.e. a Koller 'K 300' and an Hinteregger 'Mini-Urus'. Times for the different working phases were evaluated and the yield of the two machines was calculated by the expression R = 60 x C/T. The influence of the load and of the concentration distance on the total time per trip was assessed by a regression of the type T = A + Bx1 + Cx2. From the analysis of the data, no difference appears between the yields of two skylines, while various technical characteristics of the machines can be pointed out. To a Mini-Urus higher simplicity in the skyline installation (orientable guideblocks) corresponds a greater height of the Koller speed spar, which entails a lower line slope under the tower yarder and, consequently, a lower probability for the tree bundle to get entagled by eventual soil protrusions during unloading operations, with resulting unproductive working times. Besides con- firming the validity of the skyline as a means of timber concentration on soil with a slope exceeding 20 %, the investigation carried out also proved that, to obtain a higher yield by the machinery, it is necessary to exploit more the carriage capacity (1 t), which during concentration trials was of some 200 kilos.