Worm 1 rotates about fixed axis A-A and has three sections, a, b and c. Each section has the same number of starts, but section a has left-hand threads while sections b and c have right-hand threads. The worm sections a, b and c mesh with three worm wheels, 2, 3 and 4, which rotate about fixed axes B, C and D. When driving worm 1 rotates, worm wheels 2, 3 and 4 rotate in the same direction.
$2817$WG,ML$