Comprehensive category for gear components that transmit rotational motion and provide speed variation. Handles a wide range of gears including spur gears, helical gears, bevel gears, worm gears, internal gears, as well as gear boxes, reduction gear units, and precision gears. Used in power transmission mechanisms for NC machine tools, automation equipment, industrial robots, conveyor systems, providing functions such as torque conversion, speed control, and directional change. Selection is possible according to specifications like module, pressure angle, and number of teeth, achieving low noise and long life through high-precision machining. Essential mechanical components for building drive systems in combination with bearings and shafts.