Pulley Ratio (Speed Ratio)
Definition
The ratio of driven pulley diameter to driver pulley diameter, which determines speed change. Speed ratio = D₂/D₁ = N₁/N₂, where larger driven pulleys reduce speed and increase torque.
Practical Note
Maximum practical ratio for single-stage belt drives is about 6:1. For higher ratios, use multiple stages or consider gear drives for efficiency.