Foldable rollover protective structures: Universal lift-assist design.

The numbers of agricultural tractor rollover fatalities occurring with foldable rollover protective structures (FROPS) in their lowered position are significant. Raising and lowering the FROPS is a time consuming and strenuous process, and operators often leave the FROPS in the folded-down position providing no protection during a rollover. The purpose of this project is to design, manufacture, and test a lift-assist mechanism to raise and lower the FROPS from the operator's seat. The lift-assist design is based on the FROPS actuation forces, FROPS and tractor dimensions, and ergonomics engineering standards [SAE J898/ISO 6682 and SAE J1814]. The design considered can be retrofitted and will not modify or compromise the FROPS structure. A universal lift-assist lever design has been constructed and successfully tested for three FROPS of different sizes meeting appropriate ergonomics engineering standards. The operator actuation forces were less than the 75 N allowable maximum, and within the zones of comfort and reach for the operator. The lift-assist design uses an energy absorbing torsional spring to accommodate heavier FROPS designs.