ホイールタイプトラクタによる集材作業について

Abstract

林内作業車による集材作業の功程に関し, つぎの点を検討した。1. 林地勾配, 集材距離と索延伸時間の関係から, 人力延伸は, 荷掛手が斜面を下り索を延伸する上荷の場合, 急峻地においても同一直線の傾向をもち集材距離の増加とともに延伸時間は増加する。しかし16°の緩い下荷の場合, 短距離集材では前者と大差ないが, 長距離になると延伸時間は前者より短かくなり, 24°の下荷になると延伸時間は集材距離とともに急激に増加し, 荷掛手の労働負担が非常に大きくなる。エンドレス組延伸は機械動力により索延伸がなされるから, 上荷, 下荷とも延伸時間に変動はなく, 集材距離に対してもあまり変動せず, ほぼ一定値になる。スカイライン索張りの場合はスカイライン上を滑車が自重降下するため, 延伸時間は集材距離の増加とともに直線的に緩やかに増加している。以上の点から延伸形式の集材距離に対する延伸時間の関係は25 - 35m以下では人力延伸, それ以上でエンドレス索張り, スカイライン索張り, とくに50m以上ではエンドレス索張りが有利である。巻取時間については, 人力延伸は他の方式に比して圧倒的に長時間を要している。これは他の方式と異なり, 集材木がハイリード形態で集材できないからである。2. 作業待ちの関係については, 集材距離の短い人力延伸の場合では運転手, 荷掛手が土場整理を手伝い, 土場作業員との相互の作業待ちは均等化している。このように仕事量の集中している部所である土場作業の一部が分担される。しかし3人組の場合, 運転手の作業待ちが更に低下し, 土場作業を分担する割合が増加するが, 荷掛手は4人組の場合と大差ない。長距離集材のエレドレス索張りでは荷掛手と運転手の作業待ちの比率が非常に大きくなり, 各々の作業部所の分化が明確化する。一方スカイライン索張りでは運転手の作業待ちは低下し, 作業の進行を規制することにもなる。3. 集材木の材積が大きいほど, 単位時間内により大量の材積を処理できる傾向にある。またその他の要素作業とも関係するから, 平均集材積について考慮し, 組人員と索張り形式の比較を検討すると, 組人員では4人組より3人組の方が, 1人当りの単位時間内処理材積は高く, 索張り形式ではエンドレス索張りの功程が最も良い結果を得た。

In the first half of this report, we point out the problems that confront the forest industry today, focus forest tractors as one way to solve them, and describe general subjects about forest tractors. In the latter half, we study the following points as to the performance of skidding operations. 1. The relation between grade of forest land or skidding distance and extending time of wire rope. We take up about extending time by a chokerman at first. When he takes a wire rope in his hands and go down on a slope; that is skidding up hill, extending time varies directly as skidding distance, even if a steep slope. On the other hand, as regards skidding down on a gentle slope, or 16°, the gradient of the linear reference has the same tendency as the former only in the range of shorter skidding distance and it becomes gentler in the range of longer one. In the case of skidding down on a steeper slope, or 24°, it becomes rapidly large. Extending of wire rope by endless system is performed by a winch. Therefore, the extending time does not change so much whether skidding up hill or down hill and short or long. It is within a constant space, or 30 to 60 seconds. Extending by skyline system is performed by gravity, or a block slides gravitationally down on a skyline, whose gradient needs to keep beyond 10°. The extending time varies gradually with skidding distance. As above-mentioned, the methods of extending by a chokerman below 25 ~ 35 meters, by endless and skyline system beyond 25 ~ 35 meters, and by endless system beyond 50 meters are the most advantageous. It takes extremely much time when a wire rope is wound in the case of extending by a chokerman. This matter is occured by the ground skidding without high lead one. 2. The relation of waiting time that happens between each worker or each extending method. Since the method of extending by a chokerman is practised in short skidding distance, an operator and a chokerman assist workers on the landing, so each worker's waiting time tends to become equal. Thus, even the former two workers participate in a part of operations that concentrate in one working field, or operations on the landing. In the case of three men's team, the operator's waiting time decreases, but the chokerman's does not change. The method of extending by endless system is used in long skidding distance, and the waiting time excluding workers on the landing is very long, so each worker's operations specialize definitely. On the other hand, in the method of extending by skyline system, the operator's waiting time is shorter, so his operations are apt to restrict the working process. 3. The bigger the volume of skidded timber is, the more the workers tend to dispose of it in a unit time, and then, the volume has a great influence on other many elemental operations. Therefore, we need to take it in mind when we compare the performance of working team, the method of extending a wire rope and so forth. We get the result that three men's team can dispose of more volume than four men's team and that the performance as to the method of extending by endless system is best.