These names are related, not interchangeable
ISO 4183:2026 places SPZ, SPA, SPB and SPC within the narrow V-belt pulley terminology based on datum width. That shared standard context does not mean the profiles can be swapped without a drive redesign.
SPA as the target family
SPA sits between smaller and larger neighboring sections in common industrial catalogues. When the existing belt is marked SPA, start with SPA rather than selecting by visual size.
When SPZ appears
SPZ is commonly associated with more compact drive layouts. If a machine currently uses SPZ, changing to SPA affects groove geometry and usually the pulley and belt selection together.
When SPB or SPC appears
SPB and SPC are larger narrow sections used in different power and envelope ranges. They should be treated as separate drive families.
What to send when the profile is uncertain
Send the belt marking, pulley groove measurements, pulley diameter, groove count and shaft information. If the belt is worn or missing, photos of the pulley groove and any machine documentation are useful.
Do not infer compliance from a label
A catalogue family name can identify the intended profile, but a project-specific claim about dimensional compliance, balancing or material requires the released product specification.
