Profile dimensions for wedge belts SPZ, SPA, SPB, SPC and classical Z, A, B, C sections, how belt length codes work (Lp/Ld), minimum pulley diameters, tensioning basics and cross-brand interchange.
| Profile | Top width (mm) | Height (mm) | Min pulley Ø (mm) | Typical power/belt† |
|---|---|---|---|---|
| SPZ | 9.7 | 8 | 63 | to ~5 kW |
| SPA | 12.7 | 10 | 90 | to ~12 kW |
| SPB | 16.3 | 13 | 140 | to ~25 kW |
| SPC | 22 | 18 | 224 | to ~60 kW |
| Z (10) | 10 | 6 | 50 | light duty |
| A (13) | 13 | 8 | 71 | to ~3.5 kW |
| B (17) | 17 | 11 | 112 | to ~7 kW |
| C (22) | 22 | 14 | 180 | to ~15 kW |
†Order-of-magnitude per-belt figures at moderate speeds for quick sanity checks; a real drive is rated from the belt maker's power tables with service factor, speed and pulley diameters.
SPB 2360 Lp means a wedge belt, SPB section, 2360 mm pitch (datum) length. Classical belts are often quoted by inside length (Li) instead — Lp ≈ Li + a section constant (SPZ +37, SPA +45, SPB +57, SPC +79 mm as a rule of thumb), which is why a "B56" (56-inch inside) and its metric equivalent look different on paper. Raw-edge cogged versions (XPB, SPBX) fit the same grooves, run cooler on small pulleys and are the normal modern substitute for wrapped belts. The catalogue lists Gates SPZ, SPA and SPB Predator lines in lengths from under a metre to over eight.
SPZ/SPA/SPB/SPC dimensions are ISO 4184 standard, so Gates, Optibelt, Continental, SKF and Megadyne belts of the same designation interchange dimensionally. On multi-groove drives, replace belts as a complete matched set — mixing worn and new belts makes the new ones carry the load and fail early. Tension to the maker's force-deflection figure (as a first check: 16 mm deflection per metre of span at the specified test force), re-tension after the first 24–48 h of running, and align pulleys within about 0.5°; belt dressing does not belong on a V-belt.