The reason I ask is because the spindle is just a bar threaded on both ends. The top collar (5) is threaded onto the spindle clockwise (normal for the direction of travel). If the bottom collar is also threaded onto the spindle, and I think it would be, and if it was threaded clockwise then the action of cutting grass and hitting rocks etc might tend to undo it and that's dangerous. Unfortunately, I've already snapped the head of one of the bolts (45) while trying to undo it anticlockwise.
