An Assisted Folding Rear Rollbar for Agricultural Tractors: The QROPS

Statistics confirm the ROPS (Roll Over Protective Structure), in combination with the seat belt, has proved to be the most effective device for reducing victims due to agricultural tractors overturning. Nevertheless, there are still some critical situations that need to be resolved, such as the correct management of 2-post folding or tiltable rollbars, installed in front or at the rear of the tractor driver’s place. These ROPS can alternatively assume a protection (vertical) or a rest (horizontal) position. Unfortunately, due to distraction, negligence or laziness, but also because the management is fully manual (so leading to fatigue and time waste) operators often do not maintain the protection position, thus completely negating the effectiveness of the device. Automation of management would be a great advantage, even better with low-cost implementation and availability for retrofitting. The QROPS described in this paper is a two rear-post frame with “packaged” hinged sections, switching to protection condition thanks to a four-bar linkage, by means of a linear electric actuator, powered directly by the tractor battery. The mechanical locking of the hinged points is assured by hooks and ratchets, with the help of a return spring. The prototype completes the transition from rest to protection position in 7 s, thus proving suitable for a semi-automatic management, manually controlled. Furthermore, the 3-section rollbar was also validated for safety, having successfully passed the strength tests provided in OECD Code 4, for a tractor with a reference mass of 3200 kg.