Calculate belt length, center distance, and pulley diameters for V-belt and flat belt drive systems. Supports both open and crossed belt configurations with contact angle analysis.
Enter both pulley diameters and center distance to calculate belt length
Open belt drive: Pulleys rotate in the same direction. Most common configuration for machinery.
| Type | Top Width | Thickness | V-Angle |
|---|---|---|---|
| A (4L) | 13 mm (1/2") | 8 mm | 40° |
| B (5L) | 17 mm (21/32") | 11 mm | 40° |
| C | 22 mm (7/8") | 14 mm | 40° |
| D | 32 mm (1-1/4") | 19 mm | 40° |
| E | 38 mm (1-1/2") | 23 mm | 40° |
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Belt drives are essential mechanical power transmission systems used in industrial machinery, HVAC equipment, automotive applications, and more. Our calculator determines belt length, center distance, and pulley sizing for both open and crossed belt configurations, helping you design efficient and properly tensioned belt drive systems.
Belt length calculation determines the required length of a belt to connect two pulleys at a specific center distance. The formula accounts for the arc around each pulley and the straight sections between them. Open belts have both pulleys rotating in the same direction, while crossed belts cause opposite rotation.
Belt Length Formulas
Open: L = 2C + pi(D+d)/2 + (D-d)^2/(4C), Crossed: L = 2C + pi(D+d)/2 + (D+d)^2/(4C)Calculate exact belt length needed for your pulley configuration without manual measurement.
Correct belt length ensures proper tension for efficient power transmission and extended belt life.
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In an open belt drive, both pulleys rotate in the same direction, which is the most common configuration. In a crossed belt drive, the belt crosses between pulleys causing them to rotate in opposite directions. Crossed belts have higher contact angles but experience more wear.