森林作業における作業者の労働科学的研究 : トラクター集材作業における荷掛作業について

Abstract

本報告は, 森林における作業者の生理的変化を追及する一連の研究の一部で, ホイールトラクターを使用した集材作業においてもっとも心身に負担をあたえていると考えられる荷掛作業者について, 作業中の生理的変化を調査したものである。調査を行なった場所は, 三重県多気郡宮川村, 諸戸林産株式会社所有の山林内芦谷, 滝叉団地にあるスギ, ヒノキ人工林の伐採地である。対象とした作業者は, 当会社において集材作業に従事している作業者6名で, 荷掛作業の作業前, 作業中の心搏数をテレメーターで測定し, 作業者の作業中の生理的変化を調べた。結果, 作業中の心搏数は, 155回/分 - 84回/分の範囲で平均119回/分程度であった。また作業全体をとおして平均1分間当りの増加量 (生理的変化量) は50, 78程度で, 林内移動, 玉切整理, ウィンチ引出し, フック掛等の動作のはげしい作業が作業者の増加量に大いに影響しているようである。そしてその負担度は, 平地を歩行する場合を1としてみた場合2. 51であり, 伐木集材作業における玉切作業とほぼ同じ程度の負担の度合であると考えられる。

It is the purpose of this paper to point out that the properties of felling and bucking operation in the forest which conditions of the operations are severe and complicated, and that factors which will give the influence on the forest workers when with machines (a chain-saw etc.) the workers operate in the forest. For this purpose, using a wireless telemeter (Photo.-l ~ Photo.-4), the electrocardiogram and the respiration curve of workers in the operating were recorded (Photo.-5, Photo.-6). From these, the pulse and respiration frequency were calculated and the physiological responses for each operation were treated quantitatively. First, in order to clear up the factors which will strongly affect the bucking operation, the two experiments of bucking of square timbers or logs with chain-saws (using the orthogonal arrey L16 and L27) has performed on the even ground. The experimental results obtained are shown in Table 3 ~ 5 (for the arrey L16) and Table-7 ~ 8 (for the arrey L27) individually. Factor "Worker" and "Kinds of chain-saw" were significant. And it was clear up that of course the influence of weight of a chain-saw on the worker was remarkable but the influence of exhaust noise could not neglect. Next, in Table-9 the pules and respiration frequencies and their rate of increase of five workers for each condition of the operation in the felling, bucking, limbing and walking are summerized. As for A worker, in Fig.-4 the rate of increase of pulse for each poeration are shown in graphic form on the basis of the Table. And the examples of physiological response of workers during each operaiton are shown in Fig.-5 ~ 6 (by A worker) and in Fig.-7 ~ 8 (by B worker). The recovery time to the level of the pulse for before the operations was only about two minute regardless of times and kinds of the operations. We concluded from the experiment decribed above that in the forest the operations and walking with machines gave remarkable physiological load on the workers in comparison with these on the even ground, and accordingly such the operations and the walking so that the workers operated in the strained working posture with the heavy weight and high noise machine in the forest should avoid as much as possible. Properly speaking it is admirable that the workers move with driving a car from here to there in the forest and the felling or the bucking are performed through the button- or lever-operating of the machines indirectly, but speaking in view of the present situation of the forestry at least the operations should be concentrately performed on the side of the forest roads or on the wood yard of which the footholding are more favorable. If so, the workers will be able to perform their works more comfortably, safely and easily. We intend to perform the experiments with more various conditions of the operations by more various workers in order to obtain more universal results.