Calculation
i = d₂ / d₁
Diameter ratio sets speed; slip and belt stretch reduce real ratio.
i = d₂/d₁
Belt-drive ratio from pulley diameters
Diameter ratio sets speed; slip and belt stretch reduce real ratio.
MINTSI
02
Result
Select a target and calculate.
Understand the inputs
- Drive ratio i — Ratio of ideal speeds.
- Driving pulley d₁ — Pitch diameter of driving pulley.
- Driven pulley d₂ — Pitch diameter of driven pulley.
Example
100/200 mm gives i = 2 and ideally halves output speed.
Assumptions and limits
No slip; use pitch, not outside, diameter.
Sources