Input: blue and green shafts A, B
Output: pink slider C
Yellow spring forces the slider towards the shaft helical cams.
The video shows four logic states alternately:
1. A = 0; B = 0; C = 1
2. A = 1; B = 0; C = 0
3. A = 0; B = 1; C = 0
4. A = 1; B = 1; C = 0