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Objective: The aim of this study was to determine how hand space for manual insertion of flexible hoses is affected by insertion method and force. Background: Adequate space is needed during assembly tasks in which workers join parts together with their hands. Hose installations are an example of such a task. Hand clearance envelopes for insertion tasks that involve cylindrical objects, such as a hose, are currently unavailable in the literature. Methods: Participants inserted a flexible 25-mm rubber hose onto a stationary flange using simulated methods similar to those observed in field studies of automotive assembly tasks. Markers placed on the back of the hand and wrists were used to measure postures during the insertion task. Results: Hand clearance envelopes for high-force insertions were significantly larger across methods by an average of 15% for both male ( p < .05) and female ( p < .01) participants. Rocking insertions resulted in the largest hand clearance envelopes compared with other insertion methods. Rocking and twisting the hose resulted in mean increases in the cross-sectional area of the hand clearance envelopes of 35% and 24%, respectively, compared with the straight push. Differences were significant ( p < .05) for male and female participants for both bead height conditions. Conclusion: Both required insertion force and method affect hand clearance envelopes during simulated insertions. Application: These methods can be used by engineers to determine if there is adequate clearance for the hand to grip selected objects.

Objective: To quantify the physical demands of hose insertion tasks in automotive assembly operations and how they are affected by method and the mechanical interference between the hose and the flange. Background: Insertion tasks were identified by workers as physically demanding and can often lead to fatigue or losses in production attributable to pain or injury. Methods: Six male and 6 female participants pushed a 25.4-mm flexible rubber hose onto a stationary flange during simulated insertions. Three insertion methods — rock, straight, and twist — were examined in the study. Muscle activity of the finger flexors was recorded to estimate grip effort during the simulated insertions. Results: The twist method (114.8 N) resulted in a 26% reduction in axial force compared with the straight method (155.7 N). Average muscle activity ranged from a low of 14% maximum voluntary contraction (MVC; men, straight method) to a high of 67% MVC (women, twist method). Hose resultant forces ranged from a low of 52.2 N to a high of 461.1 N for all participants. Men exerted 6% higher resultant forces with 37% less muscle activity than women. Conclusion: There are situations when the 26% reduction in the axial force attributable to twisting may be helpful during an insertion, despite the fact that forearm muscle activity was highest for both male and female participants during twisting insertions. Application: The results of this study can be applied to the future design of tasks that involve the joining of two parts such as a hose and flange.