DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu
ŠUMARSKI LIST 11-12/1978 str. 27 <-- 27 --> PDF |
SUMMARY Relation between the time consumption and lower limit ot the primary conversion of Fiv trees The author deals with the problem of lower limit (of the diameter at the small end of the stems) in the primary conversion of Fir trees. Usually the stem and the top section of the trees up to the diameter of 7 cm outside bark are converted. In the time study the author applied the work sampling method, and the sterns for this purpose were divided into the sections of 4 m in length. Only the top sections could be shorter. B. h. d. of treated trees ranged betwen 35 and 75 cm. It was established that the time consumption per 1 m3 of converted volume at top sections for the barking was about twice, and for the trimming on the average even seven times longer than at the other (lower) part of the stem. Therefore, if the top sections are omited, the time consumption for the trimming and barking of converted volume per tree shortens absolutely and relatively in a higher degree than the omited wood volume. Three variants of the primary conversion were treated: 1. The conversion of stems up to the diameter of 7 cm outside bark at the small end; 2. The top section of the 2 m average length were omited; 3. Two top sections of the 6,3 m average length were omited. All diminutions of the time consumption and of the wood volume, mentioned further, represent the average value for all treated trees. In the second variant the wood volume per tree, in relation to the first variant, diminished by 1,2%; the time consumption for the trimming by 8,6%, for the barking by 2,6B/a, and the both consumptions together by 5,2%. At the 3. variant the above mentioned diminutions amount up to 5,1%; 28,8%; 9,9´V» and 17,8 % respectively. Furthermore, the effective time which was divided into two parts and that: the fixed (invariable) time and the variable time, was treated. To the fixed time belong the following work operations: Walking from tree to tree, felling and beard outting off. These work operations are fixed, because their time consumption per tree is the same, irrespectively of the converted part of the stem. The variable work operations are: trimming, barking, marking for cross-cutting and cross-cutting. The time consumption per tree of the variable times varies in individual variants, with regard to the converted length of the stem. Because of the fixed component of time, the effective time diminished in the second and third variant with the smaller intensity than the whole time consumption of trimming and barking, which dominates in the variable time. The diminution of the effective time per tree in the second variant amounts to 4,8 %, and in third variant to 15,6%, with regard to the above mentioned diminution of converted volume. The diminution of the effective time per 1 m´! of converted volume in the 2. and 3. variant is a little smaller than per tree, because the fixed time increases per 1 m3 of converted volume in the 2. and 3. variant, with regard to the diminution of the converted volume, by which the time consumption is divided. In the 2. variant, the lower limit of conversion amounts on an average to 15,6 cm, and in the 3. variant to 23,9 cm. It was found that the time consumption of the trimming for a certain round-wood section of the same diameter increases with the increasing diameter of the stern, from which the section is derived. The increasing can be threefold. The reason for it is that the round-wood of the same diameter of thicker stems lies higher on the stem, in the more branchy part. The similar increasing of the time consumption for the barking is not significant. 457 |