This disc rotates at a fixed specific speed, set by the user.

The disc weighed 5 pounds/2.3 kg and rotated at 60rps, 3600rpm (50rps in Pal).

Dr. Moffatt observed that the disc itself was not rotating very fast.

The disc rotates clockwise as seen from above.

The cycloidal disc will independently rotate around the bearing as it is pushed against the ring gear.

The discs rotated at 90 rpm, rather than 78 or 80.

When a correct key is inserted and turned, all the discs will rotate such that notches in the perimeters line up.

The middle disc rotates around its center at the same speed as the input and output shafts.

These hold the stoppers in place, so the discs and reels can rotate freely.

As she watched she could see that the disc was slowly rotating - rather like a record on a turntable.