The taper bush is the interface between a standard pulley hub and the finished shaft bore. It lets one pulley casting serve several shaft sizes, but the bush designation is not a substitute for checking the shaft diameter and keyway.
Start with the pulley model
Each catalogue row lists a recommended bush. For example, EP-SPA 200-04 uses bush 3020 and the model table lists a 75 mm maximum bore. Smaller and larger pulley diameters can use different bushes even with the same groove count.
Then confirm the finished bore
Specify the actual shaft diameter, keyway and any inch/metric requirement. The bush series has its own finished-bore options, so “3020” alone does not tell the supplier which bore you need.
Installation sequence
Clean the shaft and mating tapers, fit the key when required, seat the bush in the pulley, then tighten the screws gradually and evenly. Align the pulley with its mate before applying final belt tension. During removal, use the bush’s extraction arrangement rather than striking the pulley rim.
RFQ shortcut
Send the pulley model plus shaft diameter. If the model is unknown, send belt profile, datum/outside diameter, groove count and photos of the hub. That information is more reliable than guessing the bush from overall appearance.
Need help matching a pulley? Email [email protected] with the belt marking, shaft diameter and pulley measurements.