A Psychophysical Study of Two-Person Manual Material Handling Tasks

Abstract

Over the past ten years, there has been extensive work performed on the development of guidelines for manual material handling tasks both within individual companies and within governmental agencies. However, these guidelines address only individual, one-person lifting tasks. In both manufacturing and service industries, there are many team lifting tasks, such as furniture moving and at loading docks. This paper presents the results of a study that used psychophysical methods to investigate lifting tasks that require two workers. In addition to simple lifting tasks, the study also compared one and two-person carrying tasks. The results of the study indicate that subjects' judgments of their lifting capability are significantly greater for the two-person lifts than for the individual lifts. The same relationship was observed for the carrying tasks. These results and conclusions are important to consider when it is necessary to extrapolate from the conditions used in the development of manual material handling guidelines to other situations such as team lift carrying tasks.