The purpose of this study is to provide a comprehensive evaluation of the physical and visual limitations of youth tractor operators. Several tractor dealers and farmers offered their tractors for the study in California and Wisconsin; for a total of 44 tractors. A unique photographic technique provided 3-D digital mock-ups of the tractors, which facilitated the evaluation of reach and visual abilities of adolescents using anthropometric data. Force requirements were captured using a digital force gauge and compared to existing force requirements and databases. The results indicate, in general, that hand-operated controls tend to be out of reach for both genders with the exception of steering wheels. The worst controls were hand throttle levers. On the other hand, foot-operated controls yielded higher reachable percentages for both genders, while steering wheels showed a medium range of reachable percentages. In general, youth operators showed relatively restricted fields of vision compared to the adults, and their fields of vision decreased as obstacles were closer to the tractor. The results also showed that foot-operated controls require more strength than the recommended levels. In the meantime, the recommended physical strengths of children surpassed the activation forces for hand-operated controls. This result suggests that youth operators would be very likely exposed to muscle fatigue in the leg due to the frequent use of foot clutches and brakes during tractor operation. The study calls for a revision of existing guidelines related to determining the age of youth operators capable of operating tractors.
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