On 07/05/2019 16:30, Harry Bloomfield wrote:
Harry Bloomfield presented the following explanation :
Lawnflite 703 Autodrive. PTO clutch for deck drive was slipping, so I
decided to have a go at it. I have looked at it before, a mechanically
operated clutch (rather than electrical) and then I found it was
simply metal face, to metal face - no sign of any friction material,
but it worked, so maybe that was how it was designed to work?

Bump, someone must know?

Is a clutch ever designed to operate without any friction material just
steel against steel. There were no obvious signs of any friction
material ever having been there..

Your description of 3 balls in deepening slots made it sound more like
some designs of freewheel to me (rather than a clutch). It's certainly
true that freewheels are usually metal to metal. As TNP points out there
are also various types of metal to metal clutch. Some use sintered
bronze on hardened steel multiplates (later Norton Commandos, I
believe). You don't want steel on steel to see too much slipping, unless
it is in an oil bath.