Musculoskeletal Symptoms, Ergonomic Aspects and Psychosocial Factors in Two Different Truck Assembly Concepts

The project was carried out as a multidisciplinary correlational study of two truck-axle assembly systems (System A and B). System A (the old system) could be characterized as an unpaced line assembly system, whereas the change to the new system, System B, involved a parallelized system with longer job cycle time. The study included all permanent assembly workers in the two systems (System A 17 workers, System B 28 workers). The purpose of this study was to evaluate the two systems with respect to ergonomic factors, psychosocial factors and self-reported musculoskeletal symptoms. The job cycles were studied by means of video observation. Each subject answered a questionnaire regarding musculoskeletal symptoms and physical and psychosocial environment. The assemblers in System B were more satisfied with the physical work environment (e.g. noise, air), but less satisfied with the psychosocial environment, and the period prevalence of musculoskeletal symptoms was not lower, compared with the assemblers in System A. Video observation techniques showed that deep forward flexion was less common, but that the work was more hand intense in System B. In System B, neck/shoulder symptoms were associated principally with physical work (load) variables, whereas low back symptoms were associated with psychosocial variables