One thing I’ve noticed in many of the Ri3D videos is that the chain or pull lifted mechanisms tend to slip a little bit while they are not powered. Is there a simple and elegant way of preventing this problem? I’m aware of leadscrew anti-backlash nuts and I’m wondering if there is something similar for chain.
You could use a worm gear or some form of brake.
In the past, we’ve used lever actuated disc brakes from mountain bikes.
See the Choo-Choo people built last season. Team JVN used a ratcheting wrench on board, and loads of people (including us) machined their own paul-and-ratchet. Just install on any sprocket in the system, and design it to pneumatically (or otherwise) release when you want to go down