>>10982981It can exist in a few forms but it always will involve some sort of stressed compliant member.
I have seen it implemented in LEGO before, usually a longer axle piece is used, and the orientation can vary depending. Basically the axle is twisted along its length to take up bumps. Usually not a ton and a very long axle is used, but it does use twisting of an axle to achieve the suspension.
Have you ever put two large wheels on a long axle and gently counter rotated them and let them spring back? That spring back action is what ultimately becomes the spring in a Lego cars suspension system.
Similar setups also include using plates as leaf springs, whereby the plates get flexed like bridging a deck of cards.
Is this illegal? It stresses the parts but usually the vehicles are light enough that at rest the parts are not deformed out of their normal orientation, though I imagine over a long time of playing with the same model in the same configuration, eventually they might fatigue. I don't know.
Maybe such a vehicle constantly switches between legal and illegal depending on if it's traversing a bump.
