1. What is a Pulley RPM Calculator?

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

Purpose: It helps mechanical engineers, technicians, and DIY enthusiasts design and troubleshoot pulley systems for machinery and equipment.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The output speed is inversely proportional to the ratio of pulley diameters. A larger driven pulley will rotate slower than the drive pulley.

3. Importance of Pulley RPM Calculation

Details: Proper RPM calculation ensures equipment operates at designed speeds, prevents motor overload, and maintains optimal performance of belt-driven 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 compute the output RPM.

5. Frequently Asked Questions (FAQ)

Q1: What if I have multiple pulleys in the system?
A: Calculate each stage sequentially, using the output RPM from one pair as the input RPM for the next pair.

Q2: Does belt thickness affect the calculation?
A: For precision, measure pulley diameter at the belt's pitch line, but for most applications, using outer diameter is sufficient.

Q3: Can I use this for gear systems?
A: No, this is specifically for belt/pulley systems. Gear systems use tooth count ratios instead of diameter ratios.

Q4: What's the relationship between pulley size and speed?
A: Larger pulleys rotate slower than smaller ones when connected by the same belt. The speed ratio equals the inverse of the diameter ratio.

Q5: How do I increase output RPM?
A: Either increase input RPM, decrease driven pulley size, or increase drive pulley size.