The mechanism of the gear whose speed changes during rotation.

Ratio of size of circle A:B:C = 1:2:3


Rotary shafts X and Y are not directly connected.
A and C rotate together
B and B' rotate together

A and C have teeth attached to half of circumference. B has 1/4 on the inside and 3/4 tooth on the outside.
The distance of the inner 1/4 circumference of B and half the circumference of A are the same length.

Also,The distance of the outer 3/4 circumference of B and half of the circumference of C are the same length.
That is, when A (C) rotates at constant speed, B rotates at speed 1 when it is in contact with A, and rotates at triple speed when it is in contact with C.

This mechanism creates unequal speed rotation.
You can apply it by changing the size of the circle and the number of teeth on the circumference.


The diameter of A is 1 and the circumference is 1π.
The diameter of C is 3 and the circumference is 3π.


The diameter of B is 2 and the circumference is 2π.
1/2 of the circumference of A and 1/4 of the circumference of B are the same perimeter.
Also, 1/2 of the circumference of C and 3/4 of the circumference of B are the same perimeter.




Change in rotation speed of gear B when gear AC rotates at a constant speed.



When rotating large and small gears and medium gears as shown in the figure,
When the force point moves from the large gear to the small gear,
its speed drastically tripled.
The contact receives a large impact.



Process the shape of the tooth trace of the gear in a curved manner to increase or decrease the distance between the contact points.
The curve at that time becomes a sort of algebraic curve that gradually accelerates as it rotates.
It is supposed to be so-called spiral.As a result, the impact at the time of speed change Relax.





Apply 1/2 logarithmic spiral to each of the small gear and the large gear respectively.

Therefore, Even if the power points move from gears A and B to gears C and B, impact can be minimized.