Calculating Electric Motor RPM Pulley Calculator

Pulley RPM Equation:

\[ RPM2 = RPM1 \times \frac{D1}{D2} \]

Output RPM (RPM2):

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1. What is the Pulley RPM Equation?

The pulley RPM equation calculates the output RPM of a driven pulley based on the input RPM and the diameters of both pulleys. This is essential for designing belt drive systems in machinery and electric motors.

2. How Does the Calculator Work?

The calculator uses the pulley RPM equation:

\[ RPM2 = RPM1 \times \frac{D1}{D2} \]

Where:

\( RPM1 \) — Input RPM (rotations per minute)
\( D1 \) — Drive pulley diameter (inches)
\( D2 \) — Driven pulley diameter (inches)
\( RPM2 \) — Output RPM

Explanation: The equation shows that the output speed is inversely proportional to the ratio of the pulley diameters. A larger driven pulley will result in slower output RPM, while a smaller driven pulley will increase output RPM.

3. Importance of RPM Calculation

Details: Accurate RPM calculation is crucial for proper machinery operation, ensuring components operate within their designed speed ranges and preventing damage from excessive speeds or insufficient torque.

4. Using the Calculator

Tips: Enter the motor's input RPM and both pulley diameters in inches. All values must be positive numbers. The calculator will compute the output RPM of the driven pulley.

5. Frequently Asked Questions (FAQ)

Q1: Can I use this for metric measurements?
A: Yes, as long as both diameters use the same units (e.g., both in mm or both in cm), the ratio will be correct.

Q2: Does belt thickness affect the calculation?
A: For precise calculations, use the pitch diameter (where the belt rides) rather than the outer diameter, especially with thick belts.

Q3: What if I have multiple pulleys?
A: Calculate each stage sequentially. The output RPM from one stage becomes the input RPM for the next.

Q4: How does this relate to torque?
A: As RPM decreases, torque increases proportionally (ignoring efficiency losses). The power remains approximately constant.

Q5: What's the minimum/maximum RPM ratio?
A: Practical limits depend on belt type and pulley sizes. Typical belt drives handle ratios up to about 10:1. Higher ratios may require multiple stages.