Just from an academic standpoint, is a Roll-Over Protective Structure designed to deal with the forces resulting from an end over flip? I know it should help some if you should happen to flip the tractor over it's tail or nose, but isn't the primary function to protect during a roll along the longitudinal axis? From what I remember of the JD literature, they make a point of the fact that their ROPS is tall enough to protect your head when the tractor is totally upside down with the ROPS and hood being the ground contact points, implying that not all brands do that.
I don't know what the OSHA standard or whatever regulation resulted in the things being required calls for, but based on the above, I suspect it only involves rolls along the longitudinal axis. Does anyone have access to the "rules" manufacturers have to follow when designing a ROPS? Are they something like the passenger protection standards we have for cars in that they specify how much protection should be afforded in specific defined situations in the hopes that there will be enough carryover to save your noggin if you do something else, too?
Soundguy -- I think any foldable unit will see a lot of the forces in a roll taken up by the hinge pin and through pin. They're what keeps the flange pieces in the loose contact they have. If firm contact along the flange mating surface was important, there would probably be some kind of camming arrangement like on a chain binder to close the things tightly. On mine, the small flange seems more intended to help line up the holes for the pin when the ROPS is upright rather than being a load bearing component. The pin itself appears to be something better than grade 2 steel, and I can move the top section back and forth along the hinge when it's up. The closure is by no means tight, and the angle of the thing causes the top to lean back on the pins hard enough to keep it from rattling -- unless I'm going down one of my steeper hill sections.
