A reduction drive is a mechanical device to shift rotational rate. A planetary gearbox Planetary reduction drive is a little scale version using ball bearings within an epicyclic arrangement instead of toothed gears.

Reduction drives are used in engines of all kinds to increase the amount of torque per revolution of a shaft: the gearbox of any car is a ubiquitous exemplory case of a decrease drive. Common home uses are washers, meals blenders and window-winders. Decrease drives are also utilized to diminish the rotational velocity of an input shaft to an appropriate output speed. Decrease drives could be a gear train style or belt driven.

Planetary reduction drives are usually attached between the shaft of the adjustable capacitor and the tuning knob of any radio, to allow fine adjustments of the tuning capacitor with simple actions of the knob. Planetary drives are used in this situation in order to avoid “backlash”, making tuning easier. If the capacitor drive has backlash, when one efforts to listen in a station, the tuning knob will feel sloppy and it’ll be hard to perform small adjustments. Gear-drives could be made to have no backlash by using split gears and springtime tension however the shaft bearings need to be very precise.