Manual Materials Handling

Abstract

Maunal materials handling (MMH) tasks (pushing, pulling, lifting, lowering and carrying) are the leading source of workers' compensation claims (Dempsey and Hashemi). MMH remains a common exposure in many industry sectors including manufacturing and service occupations. The most effective means of minimizing risk is through the application of engineering controls-either removing the exposure through automation or reducing it through ergonomie design or mechanization. The specific tasks, machines and/or equipment to be modified are often selected based on the results of a detailed ergonomie analysis. Since the late 1970s, Liberty Mutual Group has been analyzing and evaluating lifting, lowering, pushing, pulling and carrying tasks using psychophysical tables (hereafter referred to as "tables") developed with the psychophysical approach. This approach specifies a response to subjects performing MMH tasks through instructions (e.g., do not become unusually tired, weakened, overheated or out of breath), and subjects adjust the load handled or push/pull forces (called the stimulus) until they feel they are working at the response specified in the instructions.