If a lens doesn't have a toothed ring
for the Fz to align with, then toothed plastic bands can easily be zip-tied around the lens, allowing it to be smoothly controlled by the Fz.
To remove, press the latch, which unlocks the ratchet from the toothed ring
, and unscrew.
They engage when the toothed ring
moves forward but slide along the curved backsides of the teeth when the ring runs in reverse.
These gears also mesh with an outer, internally toothed ring
Thus, they differ from an ordinary parallel shaft gear trains by having a moving axis or axes: sun pinion gear, planet gear, planet carrier, internal toothed ring
Regardless of tooth shape, both surfaces at the place of contact become flattened, and at the same time the toothed ring
becomes strained near the tooth root.