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Determine Pulley Speed Formula

Pulley Speed Formula:

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

RPM
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inches

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1. What is the Pulley Speed Formula?

Definition: This calculator determines the output speed (RPM) of a driven pulley based on input speed and pulley diameters.

Purpose: It helps mechanical engineers, technicians, and DIYers design and troubleshoot pulley systems.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

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 Speed Calculation

Details: Proper pulley speed calculation ensures correct machine operation, prevents component damage, and helps achieve desired performance characteristics.

4. Using the Calculator

Tips: Enter the input RPM, drive pulley diameter, and driven pulley diameter. All values must be > 0 (D2 cannot be zero).

5. Frequently Asked Questions (FAQ)

Q1: Does belt thickness affect the calculation?
A: For precise calculations, use the pulley's pitch diameter (accounting for belt thickness), but for most applications, outer diameter is sufficient.

Q2: What if I have multiple pulleys in the system?
A: Calculate each stage sequentially, using the output RPM of one stage as the input for the next.

Q3: Does this work for belt and chain drives?
A: Yes, the same principle applies to both belt and chain drive systems.

Q4: How do I measure pulley diameter accurately?
A: Measure from one edge to the opposite edge through the center, or use a caliper for precision.

Q5: What's the relationship between speed and torque?
A: As speed decreases (RPM2 < RPM1), torque increases proportionally, and vice versa.

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