Understanding Pulley Ratios and Mechanics
In mechanical power transmission, pulleys and belts are used to change speed and torque between a driver source (like an electric motor) and a driven load (like a machine arbor or fan). The foundational law governing pulley systems is inversely proportional: smaller pulleys spin faster, while larger pulleys spin slower but deliver higher torque.
The Pulley Formula
The standard equation relating driver and driven speeds ($N$) and diameters ($D$) is expressed as:
N1 $\times$ D1 = N2 $\times$ D2
- N1: RPM (rotations per minute) of the driver pulley
- D1: Diameter of the driver pulley
- N2: RPM of the driven pulley
- D2: Diameter of the driven pulley