ABSTRACT

This chapter introduces the planetary gearset, which is much more versatile. It consists of four major components: the sun, one or more planets, a ring gear, and a carrier. The major difference between planetary gearsets and ordinary gearsets is that the planets "orbit" the sun; that is, their shafts are not fixed in space. It is this epicyclic motion that permits such interesting behavior. Planetary gearsets can behave in counterintuitive ways, which makes their analysis quite interesting. However, one can develop a few simple methods that we can apply to any gearset, no matter how complicated. Battery-powered drills are a common household tool, and planetary gearboxes are often used to reduce the speed and increase the torque produced by the DC motor. The drill under consideration will be used for drilling and driving screws. The chapter provides the kinematic relationship between all the gears and the carrier and can be used to determine the output speed of the planetary gearset.