V-Belt Sheave and Drive Sizing
Speed ratio, driven pitch diameter, belt length, service-factor design HP, and a belt-count planning estimate (ANSI/RMA IP-20 / IP-22).
Formula and source
ratio = driver_rpm / driven_rpm = D_driven / D_driver; belt length L = 2C + (pi/2)(D1+D2) + (D2-D1)^2/(4C); design_HP = nameplate_HP * service_factor; belts = ceil(design_HP / HP_per_belt).
ANSI/RMA IP-20 (Classical V-belts); ANSI/RMA IP-22 (Narrow V-belts). Gates Industrial Drive Design Manual (public).
Audience
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