Evaluation of three principles for forklift steering: Effects on physical workload

Journal article, 2013

The aim of this study was to evaluate the consequences on the physical workload of new solutions in the forklift cab environment for the driver by quantifying the physical workload on the neck, shoulders, arms and wrists as an effect of steering systems. Twelve male subjects conducted identical test cycles with three types of steering: normal, tilted and miniature. The physical load on the drivers was evaluated using goniometry, inclinometry and electromyography. No major differences were detected when comparing the normal to the tilted steering wheel. The miniature steering wheel showed, in comparison to the normal steering wheel, lower velocity for the right and left wrists, lower elevation and lower velocity for the left upper arm, a reduction in load on the right trapezius muscle, respectively, and most noticeably a 6-fold increase in the "static" load and a 10-fold decrease in the time for rest/recovery for the left wrist extensor muscles. The tilted steering wheel did not have any significant effect on the workload. However, the effects of the miniature steering wheel indicate an increased risk for over exertion resulting in disorders of the wrist and forearm for the left side. Relevance to industry: When introducing new techniques or changes in technical systems, it is essential to evaluate the effects on the human workload with objective measurements.