Forces required to operate controls on farm tractors: Implications for young operators

Abstract

Farm tractors account for the majority of fatal injuries to adolescents working in agriculture and therefore remain a leading occupational priority. The question of whether these injuries occur because adolescents are assigned tractor jobs beyond their physical capabilities has not been answered. The purpose of this study was to estimate the activation forces required to operate controls on 40 tractors in common use in the US and compare them with existing estimates of physical strength for children of varying ages and with recommended ergonomic force limits for repeatedly engaging controls. Activation forces for steering, brakes and clutch were measured on each tractor. The main study finding was that the activation forces required to operate tractors typically exceeded the physical abilities of most children aged 13 to 17 years. This raises serious questions about the ability of children to safely operate tractors in common use on US farms. This study provides an ergonomic approach for evaluating the potential mismatch between young people's strength capabilities and forces required in operating farm tractors. This approach could be used in similar situations where adolescents may operate vehicles (e.g. all-terrain vehicles), machinery or other mechanical devices requiring activation of levers and controls. Study findings potentially inform the establishment of occupational policies surrounding tractor operation by young people.

Keywords:

• agriculture
• children
• safety
• strength

Acknowledgements

This research was supported by NIOSH Research Grant #R01 OH07850 and by the University of California Western Center for Agricultural Health and Safety. The authors would like to thank the invaluable contribution of Brandon Miller, Nancy Esser, Jennifer Plasse, Erica Garcia and Victor Duraj during the data collection phase of this study. The authors extend their gratitude to John Myers at NIOSH for sharing data from the 2001 National Tractor Survey and Dr. Mark Purschwitz for technical expertise regarding tractor makes and models. Finally, the authors extend their appreciation to Dr. John Miles and Dr. James Meyers of the University of California Agricultural Ergonomics Research Center for their enduring support and guidance on this project.