A Study of Size,Distance,Height,and Frequency Effects on Manual Handling Tasks

The effects of size, distance, height, and frequency on lifting, lowering, carrying, pushing, and pulling tasks were studied in two series of experiments using a psychophysical methodology. In the first series, 10 male and 12 female industrial workers performed tasks at many different frequencies. Results indicate that the lower-frequency tasks (especially the 5-min and 30-min tasks) have acceptable weights and forces lower than those estimated in previous studies. In the second series, 12 female industrial workers performed tasks with a variety of box sizes, distances of lift, and heights of push and pull. Results indicate that maximum acceptable weights and forces for female workers are significantly lower, but proportionally similar, to the maximum acceptable weights and forces for male workers.