The number of teeth per inch of the pitch circle of a gear is called what?

The number of teeth per inch of the pitch circle of a gear is called what?

• A. Circular Pitch
• B. Diametrical Pitch
• C. Module
• D. Lead Angle

Answer: (B)

This is about how tightly teeth are packed on the gear’s pitch circle. The number of teeth per inch of the pitch diameter is called diametral pitch. Diametral pitch is defined as the number of teeth divided by the pitch diameter (in inches), so it directly tells you how many teeth fit in one inch of the pitch circle. Circular pitch, in contrast, is the actual arc length between corresponding points on adjacent teeth along the pitch circle, not a count per inch. The module is the metric equivalent of tooth size, given in millimeters per tooth, not per inch. The lead angle relates to the slope of the teeth on helical or worm gears, not to how many teeth fit per inch on the pitch circle. For example, if a gear has 20 teeth on a 2-inch pitch diameter, the diametral pitch is 10 teeth per inch.

This is about how tightly teeth are packed on the gear’s pitch circle. The number of teeth per inch of the pitch diameter is called diametral pitch. Diametral pitch is defined as the number of teeth divided by the pitch diameter (in inches), so it directly tells you how many teeth fit in one inch of the pitch circle.

Circular pitch, in contrast, is the actual arc length between corresponding points on adjacent teeth along the pitch circle, not a count per inch. The module is the metric equivalent of tooth size, given in millimeters per tooth, not per inch. The lead angle relates to the slope of the teeth on helical or worm gears, not to how many teeth fit per inch on the pitch circle.

For example, if a gear has 20 teeth on a 2-inch pitch diameter, the diametral pitch is 10 teeth per inch.