They bent or broke easily, and often were remo ed. Thus, the shields frequently were seen hanging from a shop rafter or laying in a junk pile. Years later, the totally-shielded shaft came into production. This new shield was less likely to be removed from the power take-off drives, and provided greater protection for tractor and implement operators. However, even with this improved shield, there continues to be a large number of unshielded drives-a hazardous situation likely to be with us for years to come.
Power take-off shafts generally vary with the size of the tractor.
This means that a person caught in a PTO drive unit that turns at 540 revolutions per minute, conceivably could be whipped around the shaft nine times per second. If the weight of th person caught in a PTO shaft did not cause a slow operating tractor engine to stall, the accident could be totally devastating. Power take-off accidents still are fairly common. Open power-drive lines on augers, elevators and posthole diggers cause a major share of PTO accidents. Some operators remove the master shield on the power takeoff drive from the tractor.