Originally Posted by dirtman

I've had a few broken axles and stripped pinion gears but I've not seen one locked up or twisted like that. All of the hubs that had broken axles that I found were badly abused and run till they just wouldn't go any further. The few stripped pinions were in hubs that were badly worn internally, likely run dry for years.
I could imagine what sort of havoc a loose or protruding pin could do when moving along at speed, especially with a heavier rider

As a kid, I broke an axle on a road bike and the rear end locked up while descending a hill, it wasn't a fun experience

I would suppose with a three speed hub, if something broke or locked up at speed, the forces could be amplified even greater than with a straight axle. If the driver locked up, the effect would be simply a fixed gear situation, but if you lost a set of pawls combined with a loose pin or some shrapnel in the mix, the planetary gears could exert some serious force on the axle as various components stopped turning. I wonder if the planetary gears could create a reverse gear situation if one set of pawls were either engaged or not there in the right combination.
Either way I can imagine the crunching and grinding sounds that had to make as it locked up.