An investigation of the physical parameters of PTO entanglements
Power take-off (PTO) drivelines are a commonly recognized hazard of agricultural work environments. Manufacturers commonly shield PTOs to try to prevent operators from coming in contact with rotating PTO shafts. Despite the efforts of manufacturers and educators, PTO entanglements are still a common cause of agricultural work-related injuries. Researchers have explored the demographics of workers injured by PTOs, the types of activities being conducted at the time of injury, the condition of PTO shields and guards, and operator behaviors and attitudes associated with PTO risks; however, the literature is devoid of data addressing the physical parameters of how and why PTO entanglements occur. The pilot research contained in this thesis is the first step in understanding the physics of how PTO entanglements occur. Three variables were explored during this research - type of material, angle of introduction, and length of material extending below midline of PTO knuckle, that lead to the occurrence or nonoccurrence of a PTO entanglement at an exposed knuckle joint were identified and documented through use of logistic regression. The results of this study show that lighter materials, such as cotton thread, have substantially higher probabilities of becoming entangled in the PTO knuckle than do heavier materials, such as leather boot laces. Materials introduced at angles perpendicular or close to perpendicular to the PTO shaft have higher probabilities of becoming entangled. Longer materials or those that extend further below the midline of the PTO knuckle have higher probabilities of becoming entangled than do shorter materials. The results of this study also show that all PTO entanglements occurred on the side of the PTO knuckle that was on the downward side of the knuckle's rotation. The outcomes of this study will increase the understanding of the physical parameters of PTO entanglements. These outcomes will also afford a continuation of this line of research addressing the long-term goal of developing a generalized model of PTO entanglements in order to make recommendations for improved intervention strategies grounded in a thorough understanding of the physical phenomena involved.