Belt Drive Service Factor Calculator

Inputs

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Pick the class whose example machines best match the driven equipment (see the table below the calculator).
Normal torque: standard AC induction (design A/B), shunt DC. High torque: design C/D, single-phase, slip-ring, and internal-combustion engines.
Hours per day the drive runs.
Nameplate power of the driver. The belt drive is selected for P × service factor.
kW

Results

Default result
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Service factor(SF)
1.2
Pass

Class examples: machine tools, generators, line shafts, fans over 10 hp, belt conveyors, presses/shears, printing and laundry machinery, rotary PD pumps, vibrating screens.

From the classic machine-class × driver × duty table (1.0-1.8).

Also computed

Design power(P·SF)4.48kW

Rate the belts and sheaves for this, not the nameplate.

Method notes 4 notes
  • Classic V-belt service factor table (Gates-style). Published manufacturer tables differ by about ±0.1 in some cells; the drive supplier's manual governs production selections.
  • Adders beyond this table per the manufacturer manual: backside idlers, speed-up drives, dusty/hot environments and frequent starts typically add 0.1-0.2 each.
  • Synchronous (toothed) belts, chains and gear drives use their own service-factor tables — this one is for classical V-belts.
  • Choke or stall-prone loads (severe class) may warrant sizing on motor breakdown torque rather than nameplate power.

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