Off-road transport by different forest machines. A practical and theoretical analysis of effects of various terrain factors on the machine's travel speed and stability
1985
Froensdal, J. (Norsk Inst. for Skogforskning, Aas (Norway). Avd. for Driftsteknikk)
The aim of this report has been to find speed variation under summer conditions for different types of tractors, and which factors they depend on. The stability of the same machines was also investigated. The machines which are investigated are the Mini Bruunett 578 F forwarder, Kockums 821 skidder, the four-wheel driven John Deere 2140 tractor, Volvo BM 400 tractor with half-belts and the two small track tractors Variotrac 912 and Krabat 237. The tractors were driven up- and downhill, loaded and unloaded at 90 different traces, which were exactly measured and classified regarding to slopes and surface conditions. Speed variances, delay times, slipping per cent and winding factors were exactly noticed during the field test. Fig.21-48 in the annex show the models calculated on basis of the collected materials. Models calculated from the speed variances show that for slopes greater than 30 %, the performance is 25 % of the performance in flat terrain. This result is based on the assumption that the loading and unloading time is 50 % of the gross effective time, and that load size, transport distances and operational systems have the same conditions. Chapter 4 deals with theoretical studies of the tractor's stability. It is the stability in side direction which is the limiting factor for the mobility. The machine's stability in side direction is investigated at an overturn plane. Tab.20 shows that the small crawler tractors have the best stability in side direction
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