Cobra Trailer Emergency Brake Experience

I had a trailer with a club Libelle jump off the ball on a very rough railway crossing, examination revealed that it was a combination of a worn imperial ball and a metric tow hitch.
The safety chains saved the day, and stability was not an issue.
On another none gliding trailer, the coupling on the trailer my brother failed to put the chains on, and the trailer came off and crossed to the opposite side of the road, where another vehicle just missed.
I’m far happier to chain the trailer and risk myself, than to not and risk others.