V-Belt Length Calculator
Calculate belt length from pulley diameters & center distance
दो pulley के diameter और center distance से belt length निकालें
V-belt pitch length is the length of the neutral line of the belt as it wraps around the drive and driven pulleys. The formula is: L = 2C + π × (D + d)/2 + (D − d)² / (4C), where L is belt pitch length, C is center distance between pulleys, D is the large pulley pitch diameter, and d is the small pulley pitch diameter — all in mm. Classical V-belt sections (A, B, C, D, Z) and narrow sections (SPZ, SPA, SPB, SPC) are standardised. Endura Hi-Tech, a major Indian V-belt brand, makes all of these plus cogged versions. Once you compute pitch length, add the section's belt-top adjustment (typically 2 to 16 mm depending on section) to get the nominal 'outside length' stamped on the belt. This calculator outputs both pitch length and nominal length, and recommends the closest standard Endura belt size.
Calculator
Driver pulley (motor side)
Driven pulley (load side)
Between the two shaft centers
Pitch length in inches: 61.46". For 2+ belt drives, order a matched set.
ƒFormula
L = 2C + π × (D + d) / 2 + (D − d)² / (4C)L = V-belt pitch length (mm). C = center distance between pulley shafts (mm). D = large pulley pitch diameter (mm). d = small pulley pitch diameter (mm). This approximation is accurate to within 0.1% for typical belt drive ratios.
Units: All inputs and output in millimetres (mm); alternate inches output provided
V-belt ki length kaise nikaalein?
V-belt length do pulley ke diameters aur unke beech ki center distance pe depend karta hai. Formula: L = 2C + π × (D + d)/2 + (D − d)² / (4C). Yahan C center distance, D bada pulley ka pitch diameter, aur d chhota pulley ka pitch diameter hai — sab mm mein. A, B, C, D, Z — yeh classical V-belt sections hain. SPZ, SPA, SPB, SPC — yeh narrow sections hain (zyada power transmit karte hain chhote space mein). Endura Hi-Tech, Fenner, Gates — sabhi Indian brands standard sizes banate hain. Pitch length nikaal ke, section ke hisaab se belt ki top width ke liye adjustment add karein, aur nearest standard belt size order karein.
Worked Examples
Motor to pump belt drive
Problem: A 2 HP motor with 100 mm pulley drives a water pump with 250 mm pulley. Shafts are 500 mm apart. Which A-section belt fits?
Solution: L = 2(500) + π × (350/2) + 150²/(2000) = 1000 + 549.8 + 11.25 = 1561 mm. Nearest standard: A61 (1549 mm) or A62 (1575 mm). Pick A62 with take-up for tensioning.
Compressor drive with twin belts
Problem: Air compressor: 150 mm motor pulley, 350 mm flywheel pulley, 750 mm center distance. B section.
Solution: L = 2(750) + π × (500/2) + 200²/(3000) = 1500 + 785.4 + 13.33 = 2299 mm pitch length. Nearest: B89 (2311 mm) or B90 (2337 mm). Pick B89.
Upgrading from A to SPA for more power
Problem: A 7.5 HP drive using A-section has two belts slipping. Swap to SPA?
Solution: SPA belt transmits more HP per belt due to wedge geometry. For the same layout (100/250 mm pulleys, 500 mm center), the SPA pitch length formula yields 1565 mm — order SPA1557 (nearest standard) and switch to matching SPA groove pulleys.
Endura V-Belt Standard Pitch Lengths — A, B, SPZ, SPA
| Belt Size | Section | Pitch Length (mm) | Outside Length (mm) |
|---|---|---|---|
| A40 | A (13 × 8 mm) | 1029 | 1060 |
| A50 | A (13 × 8 mm) | 1283 | 1314 |
| A60 | A (13 × 8 mm) | 1537 | 1568 |
| A62 | A (13 × 8 mm) | 1575 | 1606 |
| A70 | A (13 × 8 mm) | 1791 | 1822 |
| A80 | A (13 × 8 mm) | 2045 | 2076 |
| B50 | B (17 × 11 mm) | 1314 | 1354 |
| B70 | B (17 × 11 mm) | 1822 | 1862 |
| B89 | B (17 × 11 mm) | 2311 | 2351 |
| B100 | B (17 × 11 mm) | 2590 | 2630 |
| SPZ1000 | SPZ (10 × 8 mm) | 1000 | 1012 |
| SPZ1250 | SPZ (10 × 8 mm) | 1250 | 1262 |
| SPA1157 | SPA (13 × 10 mm) | 1157 | 1175 |
| SPA1557 | SPA (13 × 10 mm) | 1557 | 1575 |
| SPB1250 | SPB (17 × 14 mm) | 1250 | 1272 |
| SPB1800 | SPB (17 × 14 mm) | 1800 | 1822 |
Endura and most Indian brands stock sizes in 25 mm or 50 mm length increments. Always order the nearest size and use motor base adjustment for tensioning.
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