1. What is a Pulley RPM Calculator?

Definition: This calculator determines the output RPM of a driven pulley based on input RPM and the diameters of both pulleys.

Purpose: It helps mechanical engineers, technicians, and DIYers design and troubleshoot belt-driven systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( RPM2 \) — Output RPM (driven pulley)
• \( RPM1 \) — Input RPM (drive pulley)
• \( D1 \) — Diameter of drive pulley (inches)
• \( D2 \) — Diameter of driven pulley (inches)

Explanation: The output speed changes inversely with the ratio of pulley diameters - a larger driven pulley will rotate slower than the drive pulley.

3. Importance of Pulley Calculations

Details: Proper pulley sizing ensures optimal machine performance, prevents belt slippage, and maintains desired speed ratios in mechanical systems.

4. Using the Calculator

Tips: Enter the input RPM, drive pulley diameter, and driven pulley diameter. All values must be > 0. The calculator will determine the output RPM.

5. Frequently Asked Questions (FAQ)

Q1: What if I know the desired output RPM but need to find a pulley size?
A: Rearrange the formula: \( D2 = D1 \times (RPM1 / RPM2) \) to calculate the required pulley diameter.

Q2: Does belt thickness affect the calculation?
A: For precise calculations, use the pitch diameter (center of belt thickness) rather than outer pulley diameter.

Q3: Can I use this for multi-pulley systems?
A: This calculates single-stage reduction. For multiple pulleys, calculate each stage sequentially.

Q4: What about belt length calculations?
A: Belt length depends on pulley diameters and center distance, which isn't covered by this calculator.

Q5: How accurate is this calculation?
A: It's theoretically accurate for ideal systems without belt slip, but real-world factors may cause slight variations.