A reduction drive is a mechanical device to shift rotational speed. A planetary gearbox Planetary decrease drive is a small scale version using ball bearings within an epicyclic arrangement instead of toothed gears.
Reduction drives are found in engines of all types to increase the quantity of torque per revolution of a shaft: the gearbox of any car is a ubiquitous exemplory case of a reduction drive. Common household uses are washers, meals blenders and window-winders. Decrease drives are also used to diminish the rotational rate of an insight shaft to an appropriate output speed. Decrease drives could be a gear train design or belt driven.
Planetary reduction drives are usually attached between the shaft of the variable capacitor and the tuning knob of any radio, to allow fine adjustments of the tuning capacitor with clean movements of the knob. Planetary drives are found in this situation to avoid "backlash", making tuning easier. If the capacitor drive provides backlash, when one attempts to tune in a station, the tuning knob will feel sloppy and it will be hard to perform small adjustments. Gear-drives could be made to have no backlash through the use of split gears and springtime tension but the shaft bearings have to be very precise.