Gear 4 is rigidly attached to shaft 11 and propeller blade 12 can only swivel with respect to this shaft. Pinion 1 is driven by an electric motor (not shown). Gears 4 and 5 have different numbers of teeth and mesh with planet gear 3. When the electric motor is switched off, gear 2 is stationary and rotation is transmitted from gear 4 through planet gear 3 and gears 5 and 6 to gear 7. In this case, gears 4 and 7 rotate at the same speed so that gear 8 does not rotate about its axis and the blade is not swivelled. But if the electric motor is switched on, gears 4 and 7 rotate at different speeds so that gear 8 turns and, through worm 9 and worm wheel 10, swivels blade 12.
$2970$CxG,FD$