1) Climbing knot 
Autoblock is a climbing and caving technique used in rappelling and ascending. It involves using a friction hitch around the climbing rope, and may be combined with other climbing equipment. It may also refer to a specific knot. ...
A mechanism or system that securely locks without having to manually lock it. Auto-locking carabiners have a spring-loaded gate that twists and locks when closed.
Safety gates that lock themselves when they are shut.
Spring-loaded, twisting mechanism on a carabiner gate that locks by itself when the gate is closed.