Strategies for assessing multi-task manual lifting jobs.
Proceedings of the Human Factors Society 35th Annual Meeting, September 2-6, 1991, San Francisco, California. Santa Monica, CA: Human Factors and Ergonomics Society, 1991 Sep; 35(11):809-813
Strategies for use in the determination of recommended weight limits for manual lifting jobs with variations in load weight, task geometry, frequency or duration, were discussed. One such strategy involved the computation of the Action Limit (AL), using the AL lifting equation published by NIOSH in 1981, for each task, and then the computation of the AL for the job by using the frequency weighted averages for the horizontal, vertical and distance variables across all tasks and the frequency multiplier based upon the sum of all the task frequencies. Another strategy involves the computation of the frequency independent action limit (FIAL) for each task and the frequency weighted AL for the job. Each strategy was used to assess a typical multitask lifting job. The second strategy provided a higher AL of the job, than that computed using the first strategy. The most important differences between the two methods were that the ALs derived from the first method accounted for the strength and physiological demands of the tasks, while the FIALs determined from the second strategy account only for strength; the first method used three averages and one intermediate value and the second used only one average and two intermediate values. The limitations and advantages of both strategies were discussed. The author concludes that the second strategy is more accurate in determining the demands of multitask lifting jobs than the first.
Analytical-models; Manual-lifting; Task-performance; Work-analysis; Mathematical-models; Physiological-effects; Musculoskeletal-system
Proceedings of the Human Factors Society 35th Annual Meeting, September 2-6, 1991, San Francisco, California