I'm not educated in mechanics, and there is one nagging idea I can't get answered thats related to limited slip differentials. I understand all types of diffs, and while learning them and requirements for best traction came to one idea about possibly good LSD, but, I can't imagine how it would be built. Actually, I'm not even sure if its not against some mechanical laws, although I don't see any violations. So, basically, idea is this. Take open diff, and connect output shafts to each other with bidirectional reducer gearing. This needs elaboration, as I'm well aware straightforward approach would result windup and lockup. Basic idea behind it is that when one of shafts speeds up due to loss of traction, the speedup is not stopped like with locking LSDs, but the speed difference is transferred to other shaft via reducer, like say 1.5:1. Necessary twist is that same behaviour must be present symmetrically for other shaft, ie. reducer effect should be present only when speed difference exists. Opposite behaviour, increaser 1:1.5 effect should be somehow avoided. Nonlocking transfer is needed to avoid frictional heat, unnecessary lockups in normal turns, ability to constantly differentiate and yet proportion torque. Obsession is to achieve this behaviour without using any sliding frictional surfaces, ie without clutch, but use only gearing. Closest to frictional surfaces could be worm gearing, like in Torsen diffs. Torsen is amazing device seemingly doing impossible - redirecting torque away from shaft that offers less resistence without any active clutching. Its nice device, but it has drawbacks that should be cured by idea above. Questions I'm having for this symmetric two-way reducer are: - are there any mechanical laws that forbid such device in principle? - if yes, then I'd like to understand fully why. - if there are no mech laws that forbit it, then does such thing already exist? - Do you have any ideas of whats a closest gearing arrangement to look at?