Cold Steel is perhaps best known for its invention of the Tri-Ad® lock, which they’ve proven through rigorous torture tests to be the most secure and safest folding knife locking system on the market. Designed by famed knife designer and Cold Steel collaborator Andrew Demko, the Tri-Ad®lock uses a unique combination of features that responds exceptionally to both positive and negative pressures and has been tested to hold up to 800 pounds of hanging weights.
1. The blade is shouldered around the stop pin for increased resistance to wear and tear. The stop pin buffers against, and redistributes the force pressure from the blade.
2. Extra space is provided to allow the rocker to fall deeper into the notch over time in response to normal wear and tear.
3. The full surface of the lock and blade tang mate flush together. The slightly angled lock tends to force the lock inwards under pressure instead of outward.
4. The rocker pin hole is made with extra space on either side to allow for self adjustment.
THE "STOP PIN"
The cornerstone of the Tri-Ad's™ strength, among other subtle refinements, is the inclusion of a new "stop pin" which re-distributes the load of vertical positive and negative pressures on the lock. The stop pin receives all positive pressure (pressure on the cutting edge) and transfers it into the handle frame and liners where it can be more effectively absorbed. Negative pressures on the lock produced, for example, by prying, digging, piercing or even abusive spine whacks are redistributed because the stop pin receives the forward pressure from the rocker and transfers it into the liners protecting the rocker and its pivot from failing.
Finally, outside of keeping the lock free from the buildup of pocket lint in the mechanism, the Tri-Ad®lock requires very little maintenance. It's designed to be self adjusting, in the sense that, over time as parts begin to wear, the Tri-Ad's® design will allow it to adapt so the locking bar always wedges deeper in the lock channel between the stop pin and the shoulder of the precision cut tang notch. This feature allows for a very safe and secure lock-up.