Carrier 3 and gear 4 are keyed to shaft 1 and rotate about fixed axis A-A. Two planet gears 9 of equal diameter are connected by turning pairs to carrier 3 and mesh with sun gear 8 which rotates freely on shaft 1. Gear 7 is rigidly attached to (or integral with) gear 8 and meshes with gear 6 which is rigidly attached to gear 5. Gear 5 meshes with gear 4. Planet gears 9 are keyed to screws 10 which are connected by screw pairs to carriage 2. When shaft 1 rotates, carriage 2 rotates about axis A-A and travels along this axis.
$2918$CxG,DR$