Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-2 (of 2 Records) |
Query Trace: Hudock Stephen D[original query] |
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A biomechanical assessment of hand/arm force with pneumatic nail gun actuation systems
Lowe Brian D , Albers James , Hudock Stephen D . Int J Ind Ergon 2014 44 (5) 715-722 A biomechanical model is presented to estimate user hand/arm force exertion with two pneumatic nail gun trigger systems. The sequential actuation trigger (SAT) is safer than the contact actuation trigger (CAT) but increases the user's exertion of force because the trigger must be actuated after the safety tip is held pressed against the workpiece. Time integrated hand force was calculated for a single user based on direct measurement of nail gun tip force against the workpiece (tip contact) and from estimated force to support the tool weight during transfer between nails and during idle holding. The model shows that hand/arm force increases when nailing with the SAT (relative to CAT) and with a vertically-oriented workpiece (relative to horizontal). Expressed per nail fired, the user exerted 0.13Ns (horizontal orientation) and 2.88Ns (vertical orientation) integrated hand force during tip contact with CAT compared to 26.15Ns (horizontal) and 46.08Ns (vertical) with SAT. Depending upon idle holding duration, integrated hand force during tip contact was estimated to have been 1-3% of 48-132Ns total hand force with CAT and 21-44% of 83-167Ns total hand force with SAT (average of horizontal and vertical orientations). Based on standard time allowances from work measurement systems it is proposed that efficient application of hand force during tip contact with SAT can reduce this contribution to 6-15% of 55-139Ns total hand force. The model is useful for considering differences in hand/arm force exertion between the SAT and CAT systems. RELEVANCE TO INDUSTRY: This paper presents a model of hand/arm force associated with two types of pneumatic nail gun actuation (trigger) systems. The model clarifies differences in user force exertion with the sequential actuation and contact actuation triggers to inform nail gun trigger selection decisions. |
Provisional recommended weight limits for manual lifting during pregnancy
Waters TR , MacDonald Leslie A , Hudock Stephen D , Goddard Donald E . Hum Factors 2014 56 (1) 203-214 OBJECTIVE: The National Institute for Occupational Safety and Health (NIOSH) Revised Lifting Equation (RNLE) was adapted to derive recommended weight limits (RWLs) for pregnant workers and to develop corresponding guidelines for clinicians. BACKGROUND: In the past three decades there has been a large increase in the number of women employed outside the home and remaining in the workforce during pregnancy. Practical authoritative guidelines based on accumulated evidence are needed to inform allowable work activity levels for healthy pregnant workers. METHOD: Empirically based lifting criteria established by NIOSH to reduce the risk of overexertion injuries in the general U.S. working population were evaluated for application to pregnant workers. Our evaluation included an extensive review of the literature linking occupational lifting to maternal and fetal health. Decision logic and supporting literature are presented, along with computational details. Results: Provisional RWLs for pregnant workers were derived from the RNLE, along with guidelines for clinicians. The guidelines advise against pregnant workers lifting below midshin and overhead. CONCLUSION: Based on our review of the available evidence, we present lifting thresholds that most pregnant workers with uncomplicated pregnancies should be able to perform without increased risk of adverse maternal and fetal health consequences. Except for restrictions involving lifting from the floor and overhead, the provisional guidelines presented are compatible with NIOSH lifting recommendations adopted in the early 1990s for the general working population. APPLICATION: Implementation of these provisional guidelines could protect millions of female workers in the workplace from fetal and maternal lifting-related health problems. |
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