Planetary Gears

The combination of an orbiting gear that engages with a sun gear and also an annular gear is called a planetary gear train.

We can design:

1.Planetary Gear-Trains

2.Differential Gear-Trains*

* Details to be updated for MD16

Curve Generation and Applications

The path of the center of a revolving Gear - Gear 2 in the images below - is a circle. This is not useful, or interesting. However, the path of a different Point on the revolving gear is interesting and sometimes useful.

Points on a GEAR rolling around the outside of a fixed gear. See top image (below)

Epicycloid: A curve given by a point on the pitch-circle of a gear that rolls around the outside of a stationary gear

Epitrochoid: A curve given by a point that is not on the pitch-circle of a gear that rolls around the outside of a stationary gear

Points on a gear rolling around the inside of a fixed gear. See bottom image (below)

Hypocycloid: A curve given by a point on the pitch-circle of a gear that rolls around the inside of a stationary gear

Hypotrochoid: A curve given by a point that is not on the pitch-circle of a gear that rolls around the inside of a stationary gear.

Peritrochoid: A curve given by a point on an orbiting gear, that is bigger than a fixed gear, and its center is inside the pitch circle of a stationary gear.

External Mesh

Gear 1 : Fixed to the Frame - it does not rotate

Gear 2 : Rotates about its own center AND Orbits around the center of Gear 1

Line-of-centers : Rotates. Its center of rotation is at the center of Gear 1

Internal Mesh

Gear 1 : Fixed to the Frame - it does not rotate

Gear 2 : Rotates about its own center AND Orbits around the center of Gear1

Line-of-centers : Rotates. Its center of rotation is at the center of Gear 1