1. What is a Pulley Size Vs. RPM Calculator?

Definition: This calculator determines the required pulley diameter based on RPM values and a known pulley diameter.

Purpose: It helps mechanical engineers, technicians, and DIYers properly size pulleys for belt drive systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( D \) — Calculated pulley diameter (inches)
• \( RPM1 \) — First rotational speed (RPM)
• \( RPM2 \) — Second rotational speed (RPM)
• \( KnownD \) — Known pulley diameter (inches)

Explanation: The ratio of RPMs is multiplied by the known pulley diameter to determine the required diameter for the other pulley.

3. Importance of Proper Pulley Sizing

Details: Correct pulley sizing ensures proper speed ratios, power transmission efficiency, and prevents belt slippage or excessive wear.

4. Using the Calculator

Tips: Enter both RPM values and the known pulley diameter. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What if I know both pulley diameters and need to find RPM ratio?
A: The formula can be rearranged: \( \frac{RPM1}{RPM2} = \frac{D2}{D1} \)

Q2: Does this work for any pulley type?
A: Yes, this applies to V-belt, timing belt, and flat belt pulleys when using the pitch diameter.

Q3: How does belt thickness affect the calculation?
A: For precise calculations, use the pitch diameter (OD minus belt thickness).

Q4: Can I use this for multi-pulley systems?
A: This calculates for two pulleys. For multiple pulleys, calculate each pair sequentially.

Q5: What's the typical accuracy needed for pulley diameters?
A: Standard pulleys are typically available in 1/8" or 1/10" increments - round to nearest available size.