http://www.benchmade.com/about_knives/locking_mechanisms.asp
http://www.coldsteel.com/triadlock1.html
Looking at the designs, I think the Tri-Ad's true strength is that it would be harder to make it fail mechanically or make it malfunction. I mean, if we're talking strength in relation to stress, fatigue and the materials just breaking, then I think the only reason the Tri-Ad would be "stronger" is because there's much more material in the lock-up. If you look at the actuald esign though, it seems like the plane that the blade and the lock engage on intersects the hole drilled for the pivot; if there wasn't so much material, I would consider that a weakness, especially because it forms that 90 degree angle. On the other hand, the lock-bar of the AXIS lock rests on a flat portion of the blade directly behind the pivot. Either way, though, stress seems more likely to make the blade itself break than any parts of either lock.
The only advantage I see the Tri-Ad locking having as far as stress-related strengths goes, is the way the stop-pin and the lock itself interact with each other. I for some reason the rocker pin or the lock itself snapped, the lock would be wedged in between the stop-pin and it wouldn't move forward. Then if you look at an AXIS lock, you see that if the stop-pin fails, the blade can fold upward quite a bit; with the Tri-Ad, that even if the stop-pin did fail the blade would not be able to travel as much as on an AXIS if at all. Personally though I haven't seen any other stop-pins than the one on the Kulgera, and the engagement to the liners is the weak-link in my eye--the diameter might be substantial but the actual engagement size to the liners is pretty insignificant. I think I've seen an HK model where it went straight-through the liners and scales though, and I see that as a stronger design--maybe even using the thumb-stud as a stop-pin. Either way, I think the stop-pin on my Kulgera is pretty weak, and the ability for the blade to fold upward if it breaks kinda sucks.
The bigger distinguishing advantages of the two designs come in the context that you want to use them though. I mean, one might say the AXIS lock is safer because of the one hand opening and closing, but on the other hand the Tri-Ad would be way less prone to mechanical failure or malfunction in a survival situation. I mean, imagine getting dirt and gravel in the spring enclosure for an AXIS lock in the middle of nowhere; How are you going to get it out of there? Even if you can open up the blade, is the lock-bar going to engage? Maybe you can find a stick to shove in there, but is that really a secure fix? Say you're cleaning out game, your hand and knife way up there, and some muscle or bone pushes the lock-bar back without you even realizing it and you fold it on your hand? All of these don't seem to be an issue with the Tri-Ad; seems at worst you'd need to find a small stick to dig out dirt from the engagement notch.
I don't often find myself in survival situations though, so I find the AXIS lock perfectly strong for using in the right context, when you have the right tools around and everything is optimal. It opens and closes with one hand which is very nice and arguably "safe", and if there's no worry about not having the right tools for maintenance or tools better suited for the job you're trying to do with it, then I don't see why you would want anything else, and I don't see how its lock would break before its blade would. I mean, if you're applying that much stress to it I would think you'd need a fixed blade, but that being said I think that's where the Tri-Ad's virtues are clearer--suppose you went hiking and lost your fixed blade, you'd probably be a lot more thankful you had a Tri-Ad lock than an AXIS lock. First time you needed to do maintenance or folded it onto your fingers because of malfunction, you're pretty much screwed.
Anyway those are just my modest ( yet lengthy ) opinions, even though I don't own a Cold Steel knife, and only a BM Kulgera as an AXIS lock. It's just what I would theorize based on the design drawings and what I can observe from looking at my AXIS lock. I want to see the weight-hang test, or at least get more details--how much weight are we talking about, what part of the lock failed, etc. I've Googled and can't find anything, and I kind of suspect that whatever weight it was was something completely impractical and inappropriate for a folder. I mean, are we talking in terms of an AXIS lock failing at 200 pounds and a Tri-Ad at 300, or are we talking about putting a whole thousand pounds on the Tri-Ad and it never breaking? If not, I don't see how it grants much merit to the argument of it being stronger, I think it's just the logical conclusion to come to when you look at the difference in the amount of material used. Either way, what I would be interested in knowing is if the Tri-Ad lock fails at x number pounds, then what would a fixed blade snap at? I mean, I just get the feeling we're talking about forces that would not be replicated in any real-life task.
