[PhasmaFelis]

I'd like to see a reliable source, and ideally a photo/video of the device in action. I won't say it's impossible, but it seems like it would be hard to make sure the gear rotates smoothly instead of binding, and "Feynman says that a guy he worked with heard about it" isn't as convincing as it might be.

[onetwofiveten]

The shaft passer shown here has never been used in real life. The mechanism that's on each of the spokes of the cog has been used in real life to allow cables to pass each other (just imagine one of the spokes and the obstructive shaft are actually cables).