Document Detail


The influence of target torque and torque build-up time on physical stress in right angle nutrunner operation.
MedLine Citation:
PMID:  9494431     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study used a computer-controlled electric right angle nutrunner to investigate the relative effects of different power hand tool and process parameters on operator muscular exertions, handle stability and subjective ratings of perceived exertion. Target torque (25, 40 and 55 Nm), torque build-up time (35, 150, 300, 500 and 900 ms), and workstation orientation (horizontal and vertical) were studied. Dependent variables included EMG activity of the finger flexors, biceps, and triceps, handle velocity and displacement, work done on the tool-hand system and power involved in doing work, subjective ratings of perceived exertion, and task acceptance. Six inexperienced subjects (three females and three males) participated. Ten replications were performed for each combination of experimental conditions. The consequences of increasing the torque reaction force were greater handle instability and perceived exertion. The effect of torque build-up time on handle kinematics, muscular activity and perceived exertion was not monotonic. Among five build-up times tested, the hand was most unstable (greater peak handle velocity and power against the operator) for a 150 ms build-up time. Greater peak handle displacement, total work against the operator and average EMG were observed for 150 and 300 ms build-up times than for other build-up time conditions. Integrated EMG and EMG latency significantly increased as build-up time increased. Average EMG latency between the onset of EMG burst and the onset of torque build-up was 40 ms for a 35 ms build-up time and 330 ms for a 900 ms build-up time. Subjective ratings of perceived exertion were the least when torque build-up time was 35 ms, however greater peak torque variance was associated with this condition.
Authors:
S A Oh; R G Radwin
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ergonomics     Volume:  41     ISSN:  0014-0139     ISO Abbreviation:  Ergonomics     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-03-19     Completed Date:  1998-03-19     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0373220     Medline TA:  Ergonomics     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  188-206     Citation Subset:  IM; S    
Affiliation:
Department of Industrial Engineering, University of Wisconsin-Madison 53706, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Computers
Electromyography
Equipment and Supplies / standards*
Female
Hand Strength / physiology*
Human Engineering
Humans
Male
Physical Exertion*
Reaction Time
Stress, Mechanical
Time Factors
Torque*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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