Operator stress in palletizing tasks with restricted access and headroom

Abstract

Two sets of experiments were carried out with 15 young industrial male subjects participating in each. In the first set, the subjects palletized a box with and without handles weighing 11 kg and 22 kg in sagittally symmetrical and 45° asymmetrical plane to the right on to a 125 cm high shelf with four clearances (15 mm, 20 mm, 25 mm, and 30 mm) at a frequency of 2 lifts per minute. In the second set of experiments, the subjects palletized a box weighing 11 kg and 22 kg in sagittally symmetrical and 45° asymmetrical planes on to a 125 cm high shelf with three clearances (15 mm, 20 mm, and 25 mm), and headroom adjusted to 90% and 95% of individual stature of the subjects. Heart rate, oxygen uptake, ventilation volumes were measured and rate of perceived exertion (RPE) was determined. The statistical analyses of the results showed that the load of lift significantly affected all physiological and psychophysical variables ( p < 0.002). The handle affected the heart rate, oxygen uptake and ventilation volume ( p < 0.01). The headroom significantly affected the RPE and oxygen uptake ( p < 0.02). The asymmetry and the restriction to access had no significant effect on any physiological or psychophysical variables.