The use of certain agricultural machines equipped with parts driven by the power take off (p.t.o.), exposes the operators to the risk of catching and dragging, with dire consequences in case of accidents, which in most cases result in fatal injuries. Especially the round balers, chippers and the manure spreaders does not have, to date, effective ways to reduce these specific risks.
The solutions available on the machine are numerous, but not resolutive and focused on the systems that are exclusively effective to protect the machine kinematic chain by any breakages. Infact, the torque levels reached for the actuation, are significantly higher than those needed to harm operators.
In previous experiments, the research unit of the Florence University, had studied effective systems for decoupling of the transmission. These studies showed that to make effective a decoupler device was necessary to have an active safety, namely to ensure in rest conditions the transmission interruption.
For these reasons, within the Promosic project, the Research Unit of Florence (UR-UniFi) based on their experiences, the device, represented by the electromagnetic clutch, has employed, as the only system capable of offering an active safety, replacing, however, the inefficient control system with two types of innovative sensors, which monitors the human presence, through detection of respiratory activity, or body temperature.
The innovative aspect of this research is the implementation of a control device coupled to the electromagnetic clutch. An infrared device, with laboratory tests performed, was effectively applied on round balers and shredders machines. The tests performed by interposing the human limbs inside the sensor monitoring field, showed response times of 50 ns to 0.4 m distance.
The results have shown the high potential of the developed system for transmission decoupling. Furthermore, its cheapness, makes it a feasible solution for every the agricultural machinery manufacturers to meet the requirements imposed by current safety regulation.