An increased risk of musculoskeletal disorders, e.g. from the neck region, has been found among professional drivers of work vehicles. The purpose of this study was to identify causes of postural load and implications for vehicle design and work tasks. A second purpose was to develop the methods for measurements and analysis of head postures. Field measurements of head postures for drivers of fork lift trucks, forestry machines, and cranes were carried out. The equipment used was an electric goniometer measurement system, containing a mechanical transmission between the head and the upper trunk. Methods for data presentation and quantification were developed. The results showed that rotable and movable driver cabine improved head postures and viewing angles substantially. Narrow window frame structures and large optimally-placed windows were also advantageous. The steering wheel, controls, and a high backrest rstricted shoulder rotation, which increased head rotation in unfavourable viewing angles. Improved workspace layouts and work organization factors such as job enlargemen decreased the influence of strenuous postures. The results also showed that head postures should be analysed in two or three dimensions simultaneously, otherwise the postures taken will be underestimated in relation to the maximal voluntary movement. (A)
Abstract