title: Effects on load handling of restricted and unrestricted shelf opening clearances.
abstract: Changes in psychophysical lifting capacity with reductions in shelf opening clearances were experimentally determined. Three levels of shelf opening clearances were studied: unrestricted shelf opening clearance, loose shelf opening clearance (a clearance of 15 mm between the box width and the shelf opening), and tight shelf opening clearance (a clearance of 3 mm between the box width and the shelf opening). Two levels of lifting frequency (1 and 4 lifts/min.) and two lifting heights (floor to 0.81 m and 0.81 m to 1.52 m) were included. The metabolic energy expenditure rates and heart rates of the subjects (8 males and 8 females) at psychophysically acceptable weights of lift were also recorded to assess the physiological burden. The results indicated a decline in the psychophysical lifting capacity of the subjects as the shelf opening clearance became narrower. The decline in psychophysical capacity, compared to unrestricted shelf opening clearance for males was 9% when the shelf opening clearance was 15 mm. A further decline of almost 4% was recorded when the shelf opening clearance narrowed down to 3 mm. For females, the corresponding declines were approximately 10% and 4%. The effects of lifting frequency and height of lift were found to be consistent with previous findings.
authors.forename: A
authors.initials: A
authors.lastname: Mital
authors.forename: L W
authors.initials: LW
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001143:Arousal; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D005082:Physical Exertion; D011601:Psychophysics