This is a follow up to the post on single point of failure industry standard apparatus cable floor attachments.
Ricky points out that it’s not only the floor plate we need to consider, but the entire tie-down mechanism.
The most frequent mistake made in gyms is when some well meaning maintenance person decides to use a threaded quick link like this one:
Yes, that’s the same kind used in the new installation pictured above. Safe when used properly. Safe when threaded only once.
But in my opinion, if you’ve got those in your gym, replace. It’s possible for the threads to get stripped after repeated use. Likely you’ve seen Quick Links fail. They are untrustworthy.
UPDATE: Here’s an example of one of those Quick Links having failed.
Of the better alternatives, mountain climbing carabiners are light, strong and widely available. Get locking carabiners, just in case.
Locking carabiners have the same general shape as non-locking carabiners but have an additional sleeve securing the gate. These sleeves may be either threaded or spring-loaded twist-lock. …
There are two main kinds:
• Twist-lock
• Screw-lock
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Other suggestions:
George and Ian upgraded the attachments at Phoenix Gymnastics, Edmonton, by adding floor plates with multiple bolts, rather than just one. GREAT.
(Those still worry me when attached to a wood floor – on basketball floors, for example. I’ve seen the entire floor plate, with 4 flimsy wood screws, pull out at the same time.)
Tim Douglas linked to a new-to-me technology they’ve used called – Chemical Anchoring (PDF)
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Update.
Greg Jackson has some cautions regarding the climbing carabiners:
In rock climbing, we use very similar anchors and bolts too. I have installed quite a few of those in far more uncomfortable positions than standing on a gym floor.
The most important part of the system is proper installation – especially in relatively soft concrete. It’s common for people to be too casual while drilling the hole. You must keep the drill straight so that you don’t flute the hole and, for some anchors, you must ensure that you’ve drilled to the proper depth.
If you’re going to use two anchors, they must be at least 10 times the diameter of the anchor away from each other or from an edge, otherwise the concrete will “dinner plate”.
Chemical anchors have been used for ages. The French climbers have been using them in their famous limestone cliffs for decades.
The quick links are plenty strong if closed properly with a wrench; use Loctite Blue to seal the threads. Don’t use Loctite Red as you’ll need a blow torch to break the seal.
DO NOT use an aluminum carabiner, they will wear very fast with the repetitive movement against the sharp steel edges of the anchors. In permanent carabiner installations on rock climbs, steel quick links are used. A steel carabiner is usually huge and quite expensive as they’re used mostly for rescue and not climbing as they’re too heavy.
… So, there’s no perfect alternative to the threaded Quick Link, so far as I can see.
Decades ago we tried these U-bolts, hoping they were more reliable than the Quick Link.
I’ve never seen one fail.
Leave a comment if you’ve anything to add to this discussion.
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