Effect of Handwheel Diameter and Orientation on Torque Production Capabilities

Abstract

OCCUPATIONAL APPLICATIONSIn this study, we determined that the torque production capabilities are maximized using larger handwheel diameters (as large as 70 cm) in a horizontal orientation (0°). When using a 70 vs. 35 cm handwheel, torque production capabilities increased by 89.7%. Larger handwheels may allow operators to work at lower percentages of their maximum physical capacities, helping to reduce their risks of injuries. Handwheels at a slanted orientation (45°) reduced torque production capabilities, and therefore should be avoided in handwheel design. Our results also indicated that torque production capabilities may be considerably lower than both existing standards and the actual torque demands experienced in practice. Recommended torque limits are proposed, and cumulative distributions of the collected torque data are presented, which may serve future standard developers in defining appropriate torque limits for the health and well-being of valve operators.TECHNICAL ABSTRACT Background: Handwheels are prevalent across numerous industries for regulating the flow of material within a valve. There are, however, no well-established design guidelines for handwheels, which can be found in different diameter sizes and orientations, and often require forces beyond an operator’s physical capacity. Purpose: The purposes of this study were to: (1) determine the effects of handwheel diameter and orientation on torque production capabilities; (2) propose recommended torque limits (RTL) to accommodate operator physical strength; and (3) explore gender differences in torque production capabilities. Methods: Sixty college students (gender balanced) participated in this study. Four handwheel diameters were examined (35, 45, 60, and 70 cm), each at three different orientation angles (0, 45, and 90° from horizontal). In each diameter-orientation combination, participants performed maximal isometric torque exertions on the handwheels. Cumulative distributions of capabilities were determined, and RTLs were derived based on the 25th percentile torque strength of females. Results: As diameter increased, torque production capabilities also increased. The 0° orientation was associated with the highest torques for all handwheel diameters. The 45° orientation was associated with the lowest torques, especially at the larger diameters. Female participants had approximately half (45–51%) the torque production capabilities of male participants. The proposed RTLs ranged between 26.4 and 57.6 Nm, depending on the diameter and orientation of the handwheel. Conclusions: To maximize torque production capacity, a large diameter handwheel – as large as 70 cm – in a horizontal orientation (0°) is recommended. Handwheels in a 45° orientation should be avoided because this reduces torque production capabilities. RTLs are proposed to accommodate the torque capacity of a general population.