When a ratchet wheel and pawl are designed, the center of the wheel, the attachment point on the pawl, and the point of the wheel tooth should fall on a common ____________________.

Ratchet Wheel

A wheel or gear with teeth cut in a way that allows motion in one direction only, often used in mechanisms requiring incremental movement.

Pawl

A mechanical component that engages with another component to prevent motion in one direction, or to drive a mechanism intermittently.

Center

The point that is equally distant from all points on the circumference of a circle or the surface of a sphere; in geometry, it's the midpoint of any shape or object.