Technical guide
Reading V-belt pulley data
Four measurements decide whether a pulley fits your drive. Keep them separate when you search, measure or request a quote.
Pitch diameter (Dp) vs outside diameter (Da)
Dp is the reference diameter used in the model name and for speed ratios — for example SPZ 100X02 has Dp 100 mm. Da is the physical outside diameter you can measure with a calliper and is always larger (104 mm for that model). Never use one in place of the other.
Belt section: SPZ, SPA, SPB, SPC
The section must match the wedge belt. Nominal belt top widths are about 9.7 mm (SPZ), 12.7 mm (SPA), 16.3 mm (SPB) and 22 mm (SPC). If the pulley is unmarked, measure the groove top width and send it with your request.
Groove count
Count the grooves. Pulleys with the same Dp can have one, two, three or more grooves and different hub designs.
Taper bush interface
A number such as 1210, 1610 or 2517 names the taper bush series the pulley accepts. The catalogue maximum bore is a limit, not the finished bore. Tell us your shaft diameter and keyway standard so the bush can be specified.
Checklist for a worn or unmarked pulley
- Any marking on the hub or rim (photograph it)
- Outside diameter Da in mm
- Number of grooves and groove top width
- Bore diameter and keyway width, or the bush marking
- Overall width / hub length if known
- Quantity and delivery city or port
Dimensions on model pages are transcribed from the supplier catalogue and linked to the source page. Catalogue drawings are type drawings, not photographs of a specific item. Fit with another brand or machine is not stated unless confirmed for your request.