Recently, on the Vertical Cavers Facebook page, there was a post about breaking a crossloaded biner with a rack eye. There are documented incidents and fatalities. I even tried it a few years ago, unsuccessfully. Of course, this means I had to try it again. This time, I was successful. I actually broke three biners with just my body weight.
Here’s the best one and with some biners that I could not get to break.
Here’s the video of Brian breaking a biner.
11mm PMI Max-Wear rope
SMC 14″ straight-eye rack with SS, U-shaped bars. (my twisted-eye rack is out on loan)
Petzl Omni (half-round)
Petzl caving harness
QAS (ascender safety)
Me, about 150 pounds.
Carabiners that broke:
Two SMC Locking D Bright, aluminum. These were dirty and probably 17 years old.
One Omega Locking D, aluminum. Also, dirty and old.
Carabiners that didn’t break:
Petzl Attache. The pear shape forced the Omni (half-round) against the gate, counteracting the leverage.
Omega Locking D. Same as the one that broke. This one didn’t.
Mad Rock Ultra-Tech HMS Screw. Again, the pear shape prevented the leverage.
SMC Locking D Bright. Same as the one that broke, except clean.
This type of failure is rare. Yes, the collars broke, but I still would not call it an equipment problem. It’s more of a technique problem. A simple Rappel Test should prevent this.
The are other ways to prevent this failure. Some locking carabiners use beefier collars. You could use a screwlink instead of a carabiner. This option could potentially cause problems as screwlinks can jam or require a wrench to open. Connecting the rack eye directly to the half-round is possible, but can cause big problems when changing over while using a ropewalker system. Opposite and opposed biners are safer, but also a hassle. My current favorite option is the Black Diamond Gridlock carabiner. It isolates the rack eye away from the gate.
No matter what, do the Rappel Test. Everytime!