An epicyclic gear train (also called planetary gear) consists of two gears mounted to ensure that the centre of 1 equipment revolves around the center of the additional. A carrier connects the centres of the two gears and rotates to carry one gear, called the earth gear or planet pinion, around the additional, called the sun gear or sunlight wheel. The earth and sun gears mesh to ensure that their pitch circles roll without slide. A spot on the pitch circle of the earth equipment traces an epicycloid curve. In this simplified case, the sun equipment is set and the planetary equipment(s) roll around sunlight gear.
An epicyclic gear train can be assembled so the planet equipment rolls within the pitch circle of a set, outer gear band, or ring gear, sometimes called an annular equipment. In this instance, the curve traced by a spot on the pitch circle of the earth is a hypocycloid.
The mixture of epicycle gear trains with a planet engaging both a sun gear and a ring gear is named a planetary gear train.[1][2] In this case, the ring gear is generally fixed and the sun gear is Auto Chain driven.
Epicyclic gears get their name from their earliest software, that was the modelling of the actions of the planets in the heavens. Believing the planets, as everything in the heavens, to end up being perfect, they could just travel in perfect circles, but their motions as viewed from Earth could not end up being reconciled with circular movement. At around 500 BC, the Greeks developed the idea of epicycles, of circles traveling on the circular orbits. With this theory Claudius Ptolemy in the Almagest in 148 AD could predict planetary orbital paths. The Antikythera System, circa 80 BC, acquired gearing which was in a position to approximate the moon’s elliptical route through the heavens, and even to correct for the nine-calendar year precession of that route.[3] (The Greeks would have seen it much less elliptical, but rather as epicyclic motion.)