System design

In principle, SKF motor encoder units can be incorporated in designs in the same way as SKF deep groove ball bearings. Some specific recommendations are described below. For additional information about electric motor applications, refer to the SKF handbook Rolling bearings in electric motors and generators.
Cable outlet
The cable emerges radially from the motor encoder unit. A sufficiently dimensioned cable duct must be provided in the bearing housing or housing cover. The radial notch in the housing should have a width in the circumferential direction of 15 to 20 mm (fig. 1).
Motor encoder units in the non-locating bearing position
SKF recommends using motor encoder units in the non-locating bearing position (fig. 2). However, there is a risk that the outer ring can spin in the housing bore, especially if vibration is a factor. Therefore, SKF recommends placing an O-ring in the snap ring groove to help prevent the outer ring from spinning, which could otherwise damage the cable.
Motor encoder units in the locating bearing position

When using motor encoder units in the locating bearing position, the impulse ring, sensor body and connecting cable should not be subjected to any axial load, whenever possible. When the bearing is subjected to axial loads that act in both directions, the motor encoder unit should be mounted in such a way that the heavier axial load is transmitted to the bearing outer ring side face opposite the sensor (fig. 3).

Motor encoder units can be located axially in the housing in different ways:

  • with a snap ring in the outer ring and a cover bolted to the housing (fig. 4)
  • with a spacer sleeve and a snap ring in the housing (fig. 5)
  • with a cover engaging the outer ring (fig. 6)

Motor encoder units with d ≤ 25 mm can only be located axially via a snap ring in the outer ring.

Motor encoder units in floating bearing arrangements
When using motor encoder units in floating bearing arrangements, the outer ring should be prevented from spinning by placing an O-ring in the snap ring groove. The motor encoder unit should be mounted in such a way that the axial load acts on the bearing outer ring side face opposite the sensor.
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