I am trying to understand the very complicated mechanism.
That spring holds the drive key in the axel. The pyrite hammer can be held against the wheel under pressure, with the key in the shaft.
-or-
the pyrite hammer is dis-engaged from the shaft, with no drive key in the end of the shaft. Hammer can swing out of the way for cleaning, or a new pyrite.
Do I understand?
Raz, this is lovely workmanship. A sonnet in steel.