Checking the thermal rating – PT
The thermal rating PT of a gear unit is the power that a gear unit can transmit continuously without exceeding a specific oil temperature.
The thermal rating PT depends on the following factors:
- Ambient temperature
- Air circulation and sunlight exposure at the installation site
- Installation altitude
- Heat conduction to the base at the installation site
- Gear unit type, size, and gear ratio
- External cooling type of the gear unit
- Method of lubrication of the gear unit
- Lubricant type
- Cyclic duration factor
For the following ambient conditions, the thermal rating can be read directly from the Selection tables:
- Ambient temperature 20 °C
- Installation in a large hall (air velocity ≥ 1.4 m/s)
- Self-cooling or fan cooling.
- Base as steel support structure
- Installation altitude < 1000 m above sea level
For other ambient temperatures and lubrication types, you can calculate the thermal rating PT using the temperature factor fT and the lubrication factor fL. The resulting calculation results are approximate values. Contact SEW‑EURODRIVE to determine the exact values.
Sufficient protection from direct sunlight is absolutely necessary when installed outdoors. If the gear unit cannot be protected against direct sunlight, then the thermal calculation must be performed taking account of the actual sunlight in kW/m2.
Thermal rating of the gear unit – PT
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|---|---|---|
| ||
PT | kW | Thermal rating of the gear unit |
PTH | kW | Nominal thermal rating of the gear unit. The values in the selection tables depend on the type of cooling, mounting position, and lubrication type. |
f1 | kW | Altitude factor |
fT | kW | Temperature factor |
