On 07/05/2019 19:43, Harry Bloomfield wrote:
newshound laid this down on his screen :
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.

This is/was just steel on steel. The three balls in the slots, are just
the means to force the clutch plates tightly together, via a coil spring
and bearing.

Interesting. I guess it is just meant to be on-off. Provided the load is
high enough it probably never really slips. I wonder if it is hardened
steel, or just mild steel? Ordinary grey cast iron would probably work
OK as the graphite might help to prevent the metal picking up or scoring.