1. What is Spur Gear Pitch Diameter?

The pitch diameter (PD) of a spur gear is the diameter of the pitch circle, which is the imaginary circle that rolls without slipping with the pitch circle of a mating gear. It's a fundamental dimension in gear design and manufacturing.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( PD \) — Pitch diameter (mm)
• \( N \) — Number of teeth
• \( M \) — Module (mm)

Explanation: The module represents the size of the gear teeth and is a standardized parameter in metric gear systems.

3. Importance of Pitch Diameter Calculation

Details: Accurate pitch diameter calculation is essential for proper gear meshing, determining center distances between gears, and ensuring smooth power transmission in gear systems.

4. Using the Calculator

Tips: Enter the number of teeth (must be a positive integer) and the module (must be a positive number). The module is typically selected from standard values (1, 1.25, 1.5, 2, etc.).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between pitch diameter and outer diameter?
A: Outer diameter includes the addendum (tooth height above pitch circle), while pitch diameter is the theoretical contact point between meshing gears.

Q2: How does module relate to tooth size?
A: Module is the ratio of pitch diameter to number of teeth. Larger module means larger teeth.

Q3: Can this calculator be used for helical gears?
A: No, helical gears require consideration of the helix angle in their calculations.

Q4: What are common module values?
A: Standard modules range from 0.5 to 50 mm, with preferred values in the 1-10 mm range for most applications.

Q5: How does pitch diameter affect gear ratio?
A: The gear ratio between two meshing gears is the ratio of their pitch diameters (or number of teeth).