On the Maximum Skidding Output of the "Timberjack 380" Forest Tractor
Authors
P. Curro
Centro di Sperimentazione Agricola e Forestale - S.A.F. (E.N.C.C. Group), Roma, Italy
S. Verani
Centro di Sperimentazione Agricola e Forestale - S.A.F. (E.N.C.C. Group), Roma, Italy
Abstract
An analysis has been carried out of the skidding operations performed by the "Timberjack 380" forest tractor for an initial thinning of a Pinusradiata D. Don plantation. Knowing the maximum tractive force exerted by the tractor and allowing for the different resistances to forward movement (rolling friction, slope and load resistance), it has been calculated that the tractor can skid 10.1 m3 of material on a dry, compacted earth track, and 5.2 m3 on a wet track.
An examination of the various phases of the operations shows that total time per trip to be expressed by the following relation: s„ su -aV where su (speed of tractor without load) = 151.45 m/ min
a = 13.4352
V = volume transported
d = skidding distance.
On the basis of this relation and of the more general one expressing the output (P = 60 V/T), the maximum output was calculated for the "trip without load" phase and for the whole log removal phase. For the "trip with load" phase the maximum output, whatever the skidding distance, is obtained by transporting 5.636 m3, while, for the whole cycle, to achieve the maximum output the load should be 6.970 m3 over a distance of 800 m, and 8.180 m3 over a distance of 100 m. From the analysis carried out and the results obtained, it is clear that the tractor, to ensure maximum performance, should transport material having a high unit volume, such as that obtained from clearcut-ting operations.
