V-Belt Sheave and Drive Sizing
Speed ratio, driven pitch diameter, belt length, service-factor design HP.
Example
You enter
- Driver RPM 1750
- Driven RPM 875
- Driver shaft power (HP) 10
- Driver pitch diameter (in) 4
- Center distance (in) 20
- Belt cross-section B
- Service factor (1.0-1.8) 1.2
You get
- Speed ratio 2:1
- Driven pitch diameter (in) 8
- Belt length (in) 59.05
- Design HP (service-adjusted) 12
Details, formula, and sources
Speed ratio, driven pitch diameter, belt length, service-factor design HP, and a belt-count planning estimate (ANSI/RMA IP-20 / IP-22).
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).
Free at gates.com/literature.
Estimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.
Field names used by the API: driver_rpm, driven_rpm, driver_hp, driver_pitch_diameter_in, center_distance_in, belt_section, service_factor, ratio, driven_pitch_diameter_in, belt_length_in, design_hp
- HP per belt coarse nominal by cross-section (A 3 / B 7 / C 15 / D 30 / 3V 5 / 5V 12 / 8V 30 HP); verify against the manufacturer power tableGates Industrial Drive Design Manual
- Driver pitch diameter entered by the user; the driven diameter follows from the ratiofirst-principles drive geometry