Use of Normalized Hand Size for Subjective Rating and Performance of Handle Diameter in a Maximum Horizontal Torque Task

Abstract

An experiment was performed to evaluate the effect of handle diameter on handle comfort, finger force capability, and torque, and to predict the optimal handle diameter based on a ‘Normalized Hand Size (NHS)’ in a maximum horizontal torque task. Subjective ratings, a force glove and LIDO WorkSET were used to assess comfort, finger force capability, and torque output on six experimental handles (from 25 to 50 mm). Analysis of subjective ratings showed that the 45 mm handle diameter was the most comfortable followed by the 50 mm handle. These two handles (50 and 45 mm) showed significantly larger torque, and lower finger forces than the other handles. The ratio of handle circumference to hand length, the NHS, was applied and resulted in 86.3% and 90.7% as the ratios to obtain maximum comfort and torque, respectively. From these data the optimal handle diameters can be recommended according to users' hand sizes in horizontal torque tasks. More sophisticated methods are being used to represent mathematically the relationships between handle diameter, finger force capability, and maximum torque output.