Getting back to a clutch/brake system, I found something interesting yesterday. I'm doing some service work on a John Deere riding lawn mower for a friend and it has an electromagnetic clutch/brake for the blade drive attached directly to the motor shaft. This mower has a 22hp Briggs on it, so that means that this clutch is pretty beefy. It might be adaptable to machine tool use, could be interesting to look at. This one appeared to have 3 wires going to the coil(s), unlike an automotive air conditioner clutch that has two wires, so that might indicate that you would have an option of applying the clutch or brake independently. I haven't really looked at it too closely yet.
https://xtremeope.com/page/search-re...words=AM122969