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1

Evaluation of pliers’ grip spans in the maximum gripping task and sub-maximum cutting task

Kim D.-M., Kong Y. K.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 4

449--456

EN

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.

2

The relationship between hand anthropometrics, total grip strength and individual finger force for various handle shapes

Kong Y. K., Kim D.-M.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 2

187--192

EN

The design and shape of hand tool handles are critical factors for preventing musculoskeletal disorders (MSDs) caused by the use of hand tools. We explored how these factors are related to total force and individual finger force in males and females with various hand anthropometrics. Using the MFFM system, we assessed four indices of anthropometry, and measured total force and individual finger force on various handle designs and shapes. Both total force and individual finger force were significant according to gender and handle shape. Total grip strength to the handle shape indicated the greatest strength with D shape and the least with A shape. From the regression analysis of hand anthropometric indices, the value of R was respectably high at 0.608–0.696. The current study examined the gender and handle shape factors affecting grip strength based on the force measurements from various handle types, in terms of influence on different hand anthropometric indices.

3

Optimization of the levels of grip force, stroke rotation, frequency and grip span for a torqueing task

Bano F., Mallick Z., Khan A. A.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 1

94--104

EN

This study was to investigate the effects of grip force, frequency, stroke rotation and grip-span on discomfort and obtain best posture for hand tool users. Fifteen male participants volunteered in this study. Participants performed combined gripping with torqueing exertions for 5 min for two levels of frequency (10 and 20 exertions/min) at two levels of grip force (50 and 70 N), two levels of stroke rotation (30° and 60°) and three levels of grip-span (4.7, 6 and 7.3 cm). Therefore, a 2×2×2×3 full factorial design was used. The analysis of variance (ANOVA) showed that frequency, stroke rotation and grip-span were significant on discomfort score. Minimum discomfort and comfortable posture was found to be 90 N grip force with 10 exertions/min for 60° stroke rotation at 6-cm grip-span. The grip force, frequency and stroke rotation were found significant on EMG activity of forearm muscles using multivariate analysis of variance (MANOVA). The extensor muscles were found more activated than flexor muscles during the given task.

4

Proposal for an Indexical Method of Evaluating Risk of Hand Tool Operators’ Exposure to Mechanical Vibrations

Engel Z., Kowalski P., Zawieska W. M.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 2

183--194

EN

The article presents proposals for an indexical evaluation of exposure of hand tool operators to vibrations. The presented indices have been developed on the basis of the results of laboratory tests. The examinations studied the effect of pressure force and grip force exerted by an operator on a hand tool as well as the amplitudes and frequencies of an exciting signal on vibrations transmitted in the hand-tool handle system.