Four Bar Mechanism Release Latch
by LucidOne, published
Safety is job #1, quality is also job #1, as is innovation.
Sometimes you might be working on a project and need a way of releasing something heavy without the risk of it landing on you. This self-locking release latch can be attached to carabiners on both ends and released by pulling on a string or wire through the middle hole. If the material being held is the right size the latch will lock shut without a spring.
Due to the geometry the force needed to release the latch is pretty much independent of the load being held, this prevents the latch from jamming.
It was inspired by the sea catch release latch and Vise-Grips.
Always wear your safety glasses. Do not use for large loads without checking the material properties and calculating the maximum load. Always design with a reasonable factor of safety. Don't be dumb, be safe.
1) Make one of links zero and two. Make two of each of the rest.
2) Drill small holes out to 3mm
3) Use M3 nuts and bolts as pins, and use Loctite to keep the nuts from backing off. Rivets may also work well for these pins.
4) Add optional spring. Remove sharp edges, polish, etc.