Abstract:

The influence of handle design and handle height on horizontal pulling strength during manual materials handling tasks was investigated. Thirty volunteers pulled on four types of horizontally oriented handles with their dominant hand. Peak and steady maximum pull strengths of the subjects were measured for each handle and height combination. Grip strengths of the subjects were also measured. The effects of handle type and height on maximum pulling strengths were examined by analysis of variance and product moment techniques. The mean grip strengths of the male and female subjects were 465 and 330 newtons, respectively. The ratio of the maximum pulling strength of the female to male subjects was 0.80. Both sexes exhibited the same pattern of results. Pulling strength was decreased by an average of 37% when the handle height was increased from 1.0 to 1.75 meters. The largest peak and steady pulling forces were measured with a vertical straight handle and bar handle. The lowest forces were associated with a rounded knob type handle which had the lowest area of hand/handle contact. The authors conclude that maximum pulling strength is influenced by the hand/handle interface and handle height. Poor hand/handle interfaces, those that allow only relative low maximum pulling exertion, can be regarded as the weak link in force transmission between human and external object.