A fault tree analysis indicates that human strength limitations when using hand tools could lead to misuse of adjustable type-rollover protective structures (ROPS) for farm tractors. Manually adjustable designs for ROPS offer one way to provide wider protection against the hazard of farm tractor rollover. A task-strength study of working orchard farmes (n=23) in the age from 21 to 70 was undertaken. Two age groups of working orchadists were studied: younger than 55 years of age (n=12) and 55 and older (n=11). Pulling tasks similar to those used for adjusting ROPS using wrenches with 12-, 18 and 24 inch-handles were evaluated. The torque (applied force at a given wrench handle length) and consequently the human strength needed to adequately tighten the threaded fasteners, becomes easier as threatened-fastener-diameter decreases. For overhead pulling tasks, the older group's mean strength (133.8 lb) was 97 % of the younger group's strength (137.4 lb). However, when the pull was shoulder-height, there was a statistically significant difference in capabilities. The older group's strength was 78 % of the younger group's mean. Results of the study suggest that for working men between the ages of 55 and 70, (1) easy to use coarse-threaded fasteners no larger than 1/2 inch diameter/13 threads per inch will not compromise safety when the expected handtool is a 12-inch wrench and (2) fine-thread fasteners should be no larger than 1/2-inch diameter/20 threads per inch for the same expected wrench. Larger-diameter fasteners would be appropriate if it is expected that longer wrench handle extensions will be used.


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    Title :

    Handtool-task strength comparison between younger and older tractor operators using adjustable rollover protective structures


    Additional title:

    Vergleich der manuellen Kraft von jüngeren und älteren Schlepperführern bei der Justierung von Überrollbügeln


    Contributors:

    Published in:

    Publication date :

    1996


    Size :

    12 Seiten, 7 Bilder, 10 Tabellen, 25 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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