ABSTRACT

Tree pruning is integral to sawtimber production in South Africa, the main purpose being the production of knot-free wood and access for fire protection. Although handheld pruning tools have been used for decades, motor-manual tools have recently been introduced. However, knowledge of possible ergonomic risks and possible productivity associated with either pruning method is limited in the literature. Hence the objective of this study was to assess human workload associated with, and possible productivity gains of, motor-manual pruning against manual operations in 2.0 m and 3.5 m pruning lifts in Pinus patula stands. The study was completed in two stands in the KwaZulu-Natal Midlands of South Africa. Information collected included time study and heart rate data. Time study results showed that motor-manual operations were more productive than manual operations in both the 2.0 m and 3.5 m pruning lifts. Pruning operations fall under the “medium to heavy” workload classification. These results show promise as the first steps in investigating the effect of manual and motor-manual operations on productivity and workload of pruning operations in South Africa. However, it is recommended for this study to be repeated with gender, terrain conditions, temperature, and musculoskeletal efforts as additional factors to workload and productivity.

摘要

树木修剪是南非锯材生产不可或缺的一部分，其主要目的是生产无结木材和防火通道。尽管手持修剪工具已经使用了几十年，但最近才引入了电动手动工具。然而，文献中关于与任一修剪方法相关的可能的人体工程学风险和可能的生产力的知识是有限的。因此，本研究的目的是评估在 2.0 m 和 3.5 m 的松树修剪升降机中与手动操作相关的人类工作量和可能的生产力增益站立。该研究在南非夸祖鲁-纳塔尔中部的两个展台完成。收集的信息包括时间研究和心率数据。时间研究结果表明，在 2.0 m 和 3.5 m 修剪升降机中，电动手动操作比手动操作更具生产力。修剪操作属于“中到重”工作负载分类。这些结果表明有望作为调查手动和电动手动操作对南非修剪操作的生产力和工作量的影响的第一步。但是，建议将性别、地形条件、温度和肌肉骨骼努力作为工作量和生产力的附加因素重复进行这项研究。