Um, what kind of load were you putting on them? I wouldn't use them for anything more than closing a hasp or locking buckle; they're clearly not designed to take load, e.g. joining cuffs that are going to get struggled against.n4ge wrote: I've had two locks fail this way, neither under strenuous use Seems they've used hot glue to join metal to metal - best guess is all these locks will eventually fail.
If yo do need to do that, look at U-shackles. Most have a hole in the end of the pin through which you can thread the lock cable. Then run the end through the closed shackle and lock it, preventing the pin from being unscrewed enough to release it. Use two shackles and locks with a bit of chain between them to give yourself redundancy and room to work the shackle pins.
Alternatively, lock the cuffs separately with the time locks (again, one for each cuff gives you some redundancy), and use regular padlocks between the cuffs.