1. What is Gear Pitch Diameter?

The pitch diameter (PD) is the diameter of the pitch circle, which is the imaginary circle that two meshing gears appear to roll on without slipping. It's a fundamental dimension in gear design and manufacturing.

2. How Does the Calculator Work?

The calculator uses the pitch diameter formula:

Where:

• \( PD \) — Pitch diameter (mm)
• \( module \) — Module of the gear (mm)
• \( teeth \) — Number of teeth on the gear

Explanation: The pitch diameter is directly proportional to both the module (size of each tooth) and the number of teeth on the gear.

3. Importance of Pitch Diameter

Details: Pitch diameter is crucial for determining proper gear meshing, center distances between gears, and overall gear system design. It affects the gear's speed ratio and torque transmission capabilities.

4. Using the Calculator

Tips: Enter the module in millimeters and the number of teeth (must be positive integers). The module is typically a standard value from gear design tables.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between pitch diameter and outer diameter?
A: Outer diameter is the overall diameter of the gear including the tips of the teeth, while pitch diameter is the diameter where the teeth effectively mesh with another gear.

Q2: How does pitch diameter relate to gear ratio?
A: The gear ratio between two meshing gears is equal to the ratio of their pitch diameters.

Q3: Can this formula be used for all gear types?
A: This formula is primarily for spur gears. Other gear types like helical or bevel gears may require additional considerations.

Q4: What are common module values?
A: Common module values range from 0.5 mm for small precision gears to 10 mm or more for large industrial gears, typically following standard size progressions.

Q5: How does pitch diameter affect gear strength?
A: While pitch diameter itself doesn't directly determine strength, larger pitch diameters generally allow for more teeth and greater torque capacity.