The objective of this study is to evaluate the influences of activation mode, torque and horizontal operating distance on hand-arm response while operating in-line pneumatic screwdrivers, Hand-arm response was investigated in terms of finger force exertion, flexor digitorum electromyography, and hand-transmitted vibration. Two activation modes (push-to-start, and trigger-to-start), two torque levels (low, and high) and three horizontal operating distance (far, middle, and near) were evaluated, Thirteen healthy mate subjects drove screws into an iron plate with pre-tapped screw holes using in-line pneumatic screwdrivers in randomly ordered experimental conditions. The results indicate that the use of push-to-start mode, not only required a greater holding force involving forearm muscular exertion and middle, ring and small finger forces, but also incurred a greater hand-transmitted vibration than the use of trigger-to-start mode. Higher torque caused a greater hand-transmitted vibration and required a firmer grip than lower torque. A middle distance level (18-30 cm away from the table edge) is recommended as it is found to have the least hand-transmitted vibration and requires less finger force exertion. Relevance to industry The findings on the evaluation of the influence of activation mode, torque, and horizontal operating distance on hand-arm response can provide useful information for the design of assembly tasks using pneumatic screwdrivers as well as the design of powered hand tools. (C) 2001 Elsevier Science BN. All rights reserved.
