Pitch Circle Diameter (PCD) – Gear Terminology
The pitch circle diameter (PCD) is the diameter of the pitch circle.
A gear is a friction wheel with teeth, and the pitch circle corresponds to the outer circumference of the friction wheel and is the reference circle for determining the pitch of the gear teeth. The pitch circles of a pair of intermeshing gears are tangent to each other at the pitch point. Unlike the root circle and tip circle, the pitch circle is a theoretical dimension and cannot be precisely measured.
If the pitch circle diameter is d, then the circumference of the pitch circle can be derived by multiplying d*π.
The circular pitch, which is the distance from one tooth centerline to the next, can be calculated by dividing the circumference of the pitch circle by the number of teeth (z).
Lastly, dividing the circular pitch by π will calculate the module (m) of the gear.
1. Pitch circle diameter (d)
2. Pitch circle (πd)
3. Circular pitch (πd / z)
相关链接 - 节圆直径（PCD）