A decrease drive is a mechanical device to shift rotational rate. A planetary reduction drive is a small scale version using ball bearings in an epicyclic arrangement rather than 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 household uses are washing planetary gearbox machines, meals blenders and window-winders. Reduction drives are also utilized to decrease the rotational velocity of an insight shaft to a proper output speed. Reduction drives can be a gear train design or belt driven.
Planetary reduction drives are typically attached between your shaft of the variable capacitor and the tuning knob of any kind of radio, to allow great adjustments of the tuning capacitor with easy movements of the knob. Planetary drives are found in this situation in order to avoid “backlash”, making tuning simpler. If the capacitor drive provides backlash, when one tries to listen in a station, the tuning knob will feel sloppy and it will be hard to execute small adjustments. Gear-drives can be made to have no backlash by using split gears and springtime tension however the shaft bearings need to be very precise.