i had a request for how i rigged my steam train wheels.
so i have done a tutorial
this tutorial shows how to use an IK rig to drive a piston to turn a wheel crank and how to use simple constraints to copy the effect to a seperate set of wheels and how it can all be animated using a single empty.
i hope you find it useful, if you have any tips on how i can do better tutorials then feel free to comment!
if you wish to practice i have included the start up .blend and the complete rig .blend