Blue outter disk and pink fork rotate around a fixed axis.

Green inner disk rotates idly on the pink fork.

The arrows show which link is the driving at different times.

1. When the blue outter disk is driving, its rotation of both directions is transmitted to the green inner disk by wedging of the rollers between the blue outter disk and the green inner disk (orange rollers for anticlockwise direction, yellow rollers for clockwise direction). The rotation of the green inner disk is transmitted to the pink fork by flexible contact via springs, red bushes and rollers (yellow rollers for clockwise direction, orange rollers for anticlockwise direction).

2. When the fork is driving, its rotation of both directions is transmitted to the green inner disk by flexible contact via rollers, red bushes and springs (orange rollers for clockwise direction, yellow rollers for anticlockwise direction). The rotation can not transmitted to the blue outter disk because the wedging does not happen.

3. When the green inner disk is driving, its rotation of both directions is transmitted to the blue outter disk by wedging of the rollers between the blue outter disk and the green inner disk (orange rollers for clockwise direction, yellow rollers for anticlockwise direction). The rotation of the green inner disk is transmitted to the pink fork by flexible contact via springs, red bushes and rollers (yellow rollers for clockwise direction, orange rollers for anticlockwise direction).

In brief, the rotation of two directions can be transmitted from the outter disk to the fork. The inverse is impossible. The fork and the inner disk always rotate together.

If the outter disk is kept immobile, the rotation can be transmitted only from the fork to the inner disk. The inverse is impossible, causing jam of the mechanism. So the inner disk can not act as a driving link.