Inline Planetary Gearbox An inline planetary gearbox is a type of gearbox that uses a system of planet gears to transmit torque and reduce the speed of a rotating input shaft to a slower output shaft. In this design, the gears are arranged in a line, with the input shaft and output shaft being in line with each other, hence the name "inline." Inline planetary gearboxes are known for their high efficiency, compact design, and high torque density. They are often used in applications that require high torque and low noise, such as in robots, electric vehicles, and aerospace applications.