V-Belt Drive
Geometry of an open belt drive: pitch length, ratio and wrap angle on the small pulley. Round the result to the nearest catalogue belt length and recalculate the centre distance.
Belt length L1,916mm
- Ratio i = d₂ / d₁
- 2
- Output speed n₂
- 725 rpm
- Wrap angle on small pulley β
- 165.6 °
- Belt speed v
- 11.39 m/s
- Wrap angle 166° — at least 120° recommended
- Recommended centre distance 315–900 mm
- Belt speed 11.4 m/s — classical belts are limited to ≈ 30 m/s
METHOD
How it is calculated
L = 2C + π(d₁ + d₂) / 2 + (d₂ − d₁)² / 4C β = 180° − 2 · arcsin((d₂ − d₁) / 2C) v = π · d₁ · n₁ / 60 000
ASSUMPTIONS & NOTES
- Enter pulley pitch (datum) diameters.
- Slip is ignored; the real output speed is 1–2 % lower.
- The number of belts and power capacity depend on the section (SPZ, SPA, SPB…) and manufacturer tables.
Results are for preliminary design and checking; base the final design on the governing standard and safety factors.
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