Full definition
A single pulley casting with multiple concentric diameters (steps) machined on one shaft, each diameter providing a different drive ratio when paired with a matching multi-step pulley on the opposing shaft. The belt is manually moved between corresponding step pairs to change speed. Typically 3-5 steps, with each step providing a ratio increment of 1.4:1 to 2:1. Common in machine tools: drill presses (bench and floor models), manual lathes, milling machines, and woodworking equipment. The belt must be the same length for all step positions, which constrains the diameter combinations (sum of driver + driven diameter remains constant across all steps). Material: cast iron GG25 or aluminum. Limited to relatively light-duty, intermittent-adjustment applications. Being gradually replaced by VFDs for variable speed, but step pulleys remain popular for their simplicity, low cost, and zero-electronics reliability in workshop machines.