Failure Modes of Mission Belt

I got to know the mission belt brand from watching Shark Tank. The belt had a unique design and looked slick. I liked it right away and ordered one shortly afterwards.

From the design, replacing the buckle/pin and holes in the belts, with buckle/ratchet and hard plastic teeth on the belt, I expect that the belt has a very long functional life.

However there is an unexpected failure mode to the release lever, which uses a square cross section to open the ratchet - the locking mechanism. Due to wear to this release feature, lever malfunctions in about 22 months. The following is a gif animation of the failure phenomenon, rotating the level fails to release the ratchet. I will explain how the belt works first, then the failure mechanism.

My first mission belt after 7 and half years

How does Mission Belt Work

The belt has a great design to solve typical belt failure mode - fracture of most commonly used holes for buckle in a traditional belt. The traditional belt could have fracture of the commonly used hole(s) in a matter of a year. One may prolong the usage of the traditional belt by cutting it short at buckle side, and punch new hole as needed. 

a traditional belt - managed to use it for nearly 10 years! it functioned fine but shabby looking

The mission belt solves the  typical belt failure mode in a tradition belt - fracture of most commonly used holes for buckle. Instead of tightening the belt via latch a pin into a hole, high stress concentration at the hole which causes cracking, mission belt used hard plastic teeth to anchor the buckle/ratchet... changed the load for anchoring from nearly point load to line load , which significantly reduce stress concentration... prolong the life of the belt.  One may not see a belt cracking any more. 

Illustration of how mission belt works from MissionBelt.com 

The Failure of Mission Belt

My first mission belt leather never cracked, but I had a different problem, it is with the release lever.

The release mechanism of the lever is realized by rotating the lever. The ridges of square cross section part will have interference with the ratchet on the logo side, lift the ratchet off the belt allowing the  movement of the belt to insert or release.

the release lever

square x-section end will push the ratchet open during rotation

The ridge wears a bit every time one put on or take off the belt. In a little bit less than two years ( ~ 22.5 months), one ridge was rounded, and it can not open the ratchet any more. One may rotate the lever 90 degrees more to use the next ridge to open the ratchet, until all 4 ridges are rounded. Once this happens, one can not release the ratchet using the lever, as the gif animation showed at the beginning of the blog.

When this happens, one can not loosen the belt by rotating the lever... have to use a screwdriver or thin hard object to push the ratchet to loosen the belt!! My first belt buckle failed fully* in 7.5 years.

Another failure mode , which is more cosmetic than functional, is the rusting of the buckle surface.

rusted buckle

I also replaced the leather belt itself once, but I don't remember what caused it. Since Mission Belt sells replacement leather and buckle, that means they do have issues with both,

How to eliminate the failure mode for the release lever?

This failure mode could be resolved by coating the ratchet and the lever, make them more wear resistant, which may not fully eliminate the failure, but substantially increase the lever/ratchet life of proper function.

Another option is to change the cross section of the end of the rod from square to rectangular, make the side pushing the ratchet initially, longer. This could be an easier mechanical solution, but need to change manufacturing process. 

Option 1 is obvious, option 2 may not be obvious but a simple fix! 

* I was thinking to insert a think piece metal or plastic between the lever square end and the ratchet, or wrap a thin piece material around the square end.