Compute V-belt / flat-belt ratio and belt speed.
| Item | Formula | Source / Standard |
|---|---|---|
| Drive ratio | i = n1 / n2 = d2 / d1 | GB/T 13575.1 V-belt drive design |
| Belt pitch length | L = 2a + PI(d1 + d2)/2 + (d2 - d1)^2 / (4a) | ISO 4184 belt lengths |
| Small pulley wrap angle | alpha = 180 - 2 asin((d2 - d1) / (2a)) | ISO 155 belt drives terminology |