Service factor and duty classification: how to get it right
The service factor (fs) is the coefficient that turns real operating conditions into a safety margin on the reducer. It is the number that decides whether a reducer lasts or fails early.
What it is for
The catalogue gives rated torque under ideal conditions. In reality there are shocks, frequent starts, many hours a day. The service factor increases the required torque to account for this: rated M₂ ≥ required M₂ × fs.
What it depends on
- Load type (class): uniform (conveyors, fans), moderate shock (mixers, conveyors), heavy shock (crushers, presses).
- Running hours: 2, 8, 16 or 24 hours a day.
- Starts/hour: every start is a torque peak; many starts raise fs.
Typical values
For uniform load and moderate duty fs starts around 1.0–1.25; for moderate shock and continuous duty it rises to 1.5; for heavy shock, many hours and many starts it reaches 2.0 and beyond. Manufacturer tables cross-reference load class with hours and starts.
Do not confuse it with thermal power
The service factor guards against mechanical failure; the thermal limit is a separate, independent check. Verify both.
For full sizing, start from output torque and speed or use the selector.
Häufige Fragen
What is a gear reducer's service factor?
A coefficient that increases the required torque based on load type, running hours and starts/hour. The reducer is chosen so its rated torque exceeds the required torque multiplied by the service factor.
What service factor value should I use?
About 1.0–1.25 for uniform loads, 1.5 for moderate shock in continuous duty, up to 2.0 and beyond for heavy shock with many starts. Read it from the manufacturer tables by crossing load class with hours.