Input is the green shaft of two green pulleys (Dg dia.) rotating regularly with Vg velocity.

Output is the pink crank of Vp velocity.

The blue block of a blue small pulley (Db dia.) and a gear of Zb teeth idly rotates on the pink crank.

The yellow block of a yellow large pulley (Dy dia.) and a gear of Zy teeth idly rotates on the pink crank.

The orange gear of Zo teeth idly rotates on a pin of the pink crank.

Vp = Vg (Dg(Dy.Db)).((Db.Zy – Dy.Zb)(Zy + Zb))

This case:

Dy = 3.Dg + 3.Db

Zo = 20; Zb = 40; Zy = 80

Vp = 9.Vg

Vp can be very small by choosing appropriate pulley diameters anf gear tooth numbers in order to decrease value of ((Db.Zy – Dy.Zb).