pitch circle

American  

noun

Machinery.

1. an imaginary circle within the profiles of the teeth of a gear, such that it rotates against a similar circle rotating at the same rate on a meshing gear.

---

pitch circle British  

noun

1. an imaginary circle passing through the teeth of a gearwheel, concentric with the gearwheel, and having a radius that would enable it to be in contact with a similar circle around a mating gearwheel

---

Etymology

Origin of pitch circle

First recorded in 1810–20

Example Sentences

The arc pitch multiplied by the number of teeth in the wheel gives the circumference of the pitch circle.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua

Then for the flanks place the slant edge of the odontograph coincident and parallel with e, and let its corners coincide with the pitch circle as shown.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua

The wheel having 10 teeth was then given the form of tooth that would be obtained by rolling upon it another wheel of the same diameter of pitch circle and pitch of teeth.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua

The diameter of the pitch circle cannot be obtained from that of the addendum circle unless the pitch of the teeth and the proportion of the pitch allowed for the addendum be known.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua

Here, 20 ÷ 10 = 2 = diameter of wheel at the pitch circle.

From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua