Network optimization information:

1) Hypocycloid: when a circle rolls without sliding in the fixed circle inscribed with it, the locus of a fixed point on the circumference of the moving circle is called hypocycloid.

2) Eversion: when a circle rolls along its circumscribed fixed circle without sliding, the track of a fixed point on the circumference of the moving circle is called eversion.

The equations, images and properties of hypocycloids and epicycloids should be studied by the readers themselves. There is a kind of toy called "Huahua", which actually draws an hypocycloid curve. Cycloidal motor of green stock machine All members of the family are very beautiful. Readers may as well try to have a look.

Generally, there is no backward moving point on the wheel of a moving car, because the track of the point on the wheel of a car can only be an ordinary cycloid or a short cycloid. But the backward point can be found on the fast moving train wheels because Cycloidal motor with reducer Train wheels have special structure. It is formed by overlapping three discs. The radius of the two outer discs is greater than the radius of the inner disc. When the inner disk moves along the track, there are some swing points of the long cycloid on the outer disk.