Starting torque

The starting torque of a rolling bearing is defined as the frictional moment that must be overcome by the bearing to start rotating. Therefore, only the sliding frictional moment and the frictional moment of seals, if applied, must be taken into consideration. At an ambient temperature of 20 to 30 °C (70 to 85 °F), the starting torque can be calculated using

Mstart = Msl + Mseal

Mstart =starting frictional moment [Nmm]
Msl =sliding frictional moment [Nmm]
Mseal =frictional moment of the seals [Nmm]
However, the starting torque can be considerably higher for roller bearings with a large contact angle. It can be up to four times higher for tapered roller bearings in the 313, 322 B, 323 B and T7FC series, and up to eight times higher for spherical roller thrust bearings.
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