Full definition
Rubber Manufacturers Association Industrial Power Transmission Standard IP-20 — the North American standard defining dimensions, tolerances, and testing requirements for classical (heavy-duty) V-belts with imperial profiles: A (1/2" top width), B (21/32"), C (7/8"), D (1-1/4"), and E (1-1/2"). RMA IP-20 is the original V-belt standard that has been the primary reference in the United States, Mexico, and Canada since the widespread adoption of V-belt drives in the 1930s-1950s. Key specifications: belt cross-section dimensions, effective length (Le) designation system, length tolerances, and matching tolerances for multi-belt sets. Classical profiles are being gradually supplemented (not replaced) by narrow profiles (3V/5V/8V per RMA IP-22), which transmit 2-3x more power per belt width. However, the installed base of classical profile drives is enormous, and replacement belts in A, B, C, D, and E profiles remain among the highest-volume industrial belt products. Approximate metric equivalents: A ≈ SPA (13 mm), B ≈ SPB (17 mm), C ≈ SPC (22 mm), but cross-sections differ slightly — profiles are NOT perfectly interchangeable between RMA and ISO/DIN systems. Per RMA IP-20-2019 (now published by ARPM).