Peak volitional torques for wrenches and screwdrivers

Abstract

Effects of grip shape (regular, circular, square, and triangular), wrist orientation (3 for screwdrivers and 7 for wrenches) and duration of repeated exertions on the maximum torque males and females could exert in different postures with 4 wrenches and 4 screwdrivers were investigated experimentally. Quantitative data were collected by conducting two independent sequential experiments. Circular grips for wrenches and triangular grips for screwdrivers maximized torque exertion capability. The peak torque declined with the duration of repeated exertions but stabilized after 180 s. Wrist orientation also had a significant influence on how much torque individuals could exert. A third experiment generated torque data for two additional body postures that were not included in previous works. From this investigation, correction factors were developed to generate peak torque exertion capability data of individuals with wrenches and screwdrivers for a variety of conditions dictated by body posture, wrist orientation, duration of repeated exertions, and grip shape. The paper includes the basic torque exertion capability design data tables and the correction factors.