Comprehensive manual handling limits for lowering, pushing, pulling and carrying activities

Abstract

The objective of this study was to develop a set of mathematical models for manual lowering, pushing, pulling and carrying activities that would result in establishing load capacity limits to protect the lower back against occupational low-back disorders. In order to establish safe guidelines, a three-stage process was used. First, psychophysical data was used to generate the models' discounting factors and recommended load capacities. Second, biomechanical analysis was used to refine the recommended load capacities. Third, physiological criteria were used to validate the models' discounting factors. Both task and personal factors were considered in the models' development. When compared to the results from prior psychophysical research for these activities, the developed load capacity values are lower than previously established limits. The results of this study allowed the authors to validate the hypothesis proposed and tested by Karwowski (1983) that states that the combination of physiological and biomechanical stresses should lead to the overall measure of task acceptability or the psychophysical stress. This study also found that some of the discounting factors for the task frequency parameters recommended in the prior psychophysical research should not be used as several of the high frequency factors violated physiological limits.

Psychophysical basis for maximum pushing and pulling forces: A review and recommendations

“…The above observations are consistent with those of Shoaf et al (1997), who analyzed the effects of these parameters on the initial and sustained maximum acceptable forces.…”

A symbiotic relationship between Lean Production and Ergonomics: insights from Industrial Engineering final year projects

“…Additionally, Shoaf et al [29] developed a set of mathematical models for manual lowering, pushing, pulling and carrying activities by establishing load capacity limits to protect the lower back against occupational low-back disorders.…”

The Assembly Specific Force Atlas

“…Further developments on modeling pushpull forces can be found by Schaefer and Schaub (2006) and Schaub and Schaefer (2006). Even more comprehensive modeling that include lowering, pushing, pulling, and carrying activities can be found at Shoaf, Genaidy, Karwowski, Waters, and Christensen (1997).…”