In Germany too a snythetic rope is distributed since about two years, whose breaking load seems to be comparable to that of a wire rope. Investigations in our country and even research on a comparable product done in the USA let the new rope seem appropriate to the use on skidder winches; experts of statutory accident insurance have already authorized its specific use under obligate conditions. Especially the very low deadweight of 10 kg/100 m (guilty for the rope Dynatec 12 with 14 mm nominal diameter) has made this plastic rope a favorite for chokermen, whose opinion is coincident that there are absolutely ergonomical advantages in relation to wire ropes. Within a three day short study in a vocational school at Weilburg (Hessia) has analysed these advantages using actual work scientific methods. First time in a forestal field study a telemetric working measurement tool for spiroergometry was used that is computing human energy consumption breath by breath. The collection of these physiological data could be done synchronously with collecting the physical data "tractive" and "extraction-velocity" of the chokerman (a well experienced co-worker of the vocational school). Both physiological and physical data have been collected comparatively for the use of snythetic rope and a wire rope with the same applicational spectrum. The ropes were mounted on the drums of one (unbreaked) winch. The weight relation of steel to plastic rope was 5.6. Measurements were confined on extraction activities and the final analysis was concentrated on uphill movements. Under all external conditions the airy plastic rope was due to tractive force; physical work (external energy); human energy consumption in whole body work significantly better than the wire rope. Humans energy consumption is a classic parameter for the assessment of work intensity. The working part "collecting a choker charge" when skidding long wood will be evidently easier when using a DYNEEMA rope, required recovery interruptions will take less time. Within "long log skidding" the part "reope extraction" takes only about 20% time, but it is determining work intensity by its very high somatic strain. Relatively low forces that must be provided for extracting the synthetic rope shall not only meet with decreasing work intensity: the working process of rope extraction on forest conditions show furthermore a lot of biomechanical parallels to transporting logs by hand, and this means, there is a high potential for damaging backbones - an effect that could be shown in earlier studies. Even against this background an extension of synthetic ropes seems eligible, especially if their material-physical characteristics meet with the high standards for skidding equipment.
