Blue and green shafts rotate around a fixed axis.
The red flat springs always force the yellow balls into wedgeshaped gaps between the shafts.
The arrows show which link is the driving at different times.
When the blue shaft is driving, its two way rotation can be transmitted to the green shaft only in anticlockwise direction.
When the green shaft is driving, its two way rotation can be transmitted to the blue shaft only in clockwise direction.