Why is a certified protective guard (Zinkenschutz / Scherenschutz) legally required over the front tines of a bale fork or loader bucket during road travel?

1. To stop the tines being bent by stone chippings thrown up from the road
2. To keep the tines clean so that the paint does not corrode
3. To mark the width of the implement for following traffic
4. To cover sharp, spear-like prongs that would cause catastrophic injuries in a collision with another road user or a pedestrian