Audio jack for slip ring?

[JensR]

I use one in the circle drive of my grader.
Mono has two poles
Stereo has three poles (common ground, left, right)
There are some four-pole ones available, but I only found them for the smaller sizes, not the big 6.5mm ones.
Not sure about current - my four-pole one seems to work fine with the 1A to 2A I am sending over it.
They are not meant for many rotations and a bit susceptible to ingress of dirt, but they are a nifty way of doing that - for small models and large plugs, you might even get away without an external bearing to take the load.