Maximum Voluntary Hand Grip Torque for Circular Electrical Connectors

Abstract

A study employing twenty male and eleven female subjects was performed to determine maximum hand grip torque that can be exerted during tightening or loosening of circular electrical connectors. A static, sustained three-second exertion was used as the strength criterion. Torque was applied to simulated connector rings with diameters of 0.9, 1.5, and 2.0 inches and measured by means of a single-bridge torsional load cell. Other variables tested included the type of grip employed (full or fingertip), orientation of the connector (front, right side, or rear facing behind a barrier), the use of work gloves and chemical defense gloves, the height of the connectors (60% and 85% of the maximum reach height) and the direction of rotation. Hand grip torque strength was found to be directly related to connector diameters, with similar strength patterns exhibited for tightening and loosening. Higher torque was exerted when the connectors were on the subject's right side, and tightening and loosening effort corresponded to flexing and extending the wrist parallel to the forearms. The use of gloves resulted in higher torque in most situations. Connector height and direction of rotation had little effect on torque strength.