Involute Tooth Form – Gear Terminology
The involute tooth form is the most general gear tooth form. The involute curve is the trace that the end of a taut string produces as it is unwound from a cylinder, and the gear tooth whose cross section is the involute curve is called the involute tooth form. When two gears with involute curves mesh together, the contact point moves along the common tangent of the two base circles. Also, because the contact surface is always perpendicular to the common tangent, it has the feature of having the direction of the acting force along the same common tangent. That is to say, with involute shaped gears, the force is transmitted in one direction securely from the beginning to the end of the mesh. The characteristics of the involute gears include that even with some errors in the center distance, they can still mesh and they are easy to generate. Especially regarding the center distance, there are times when the gear shaft deflects due to the transmission of power or when the cumulative tolerance of surrounding components builds up, the ability to mesh correctly with some center distance errors is an important characteristic.
It should be noted that examples of the related terminology to involute gear forms can be listed as cycloid gear form, trochoid gear form, etc.
Involute Curve