Mixture/carb heat quadrant

Just a quick question to anyone with real world 47 experience.
Do either/neither or both the levers on the quadrant have a ratcheting mechanism similar to a GA levered mixture? I was looking through an old servicing and overhaul manual and there was a reference to both levers on the quadrant having ratchets, but I’ve never notice this on any videos I’ve seen. I can see the sense in it given the vibrations. The one I designed doesn’t incorporate ratchets, so I wondering if I need to modify the design.