Sleeve Bearings; Bearing Verification - ABB AMA Series Manual

Manual for Induction Motors and Generators

8.2.2 Sleeve bearings

8.2.3 Bearing verification

100 - Trouble Shooting
The sleeve bearings used in rotating electrical machines are often 'standard bearings' used in a
number of applications. Therefore, the bearing design in itself is normally not the cause of
bearing leakages, and the reason for the leakage should be found elsewhere.
However, the bearing is assembled from several parts, and the joints between the parts can leak
due to faulty assembly or lack of sealing compound.
Bearing housing
The bearing housing consists of an upper and lower half, which are joined together. In addition,
labyrinth seals are mounted at the bearing housing entrance of the shaft. This construction is not
completely hermetic, and therefore very small leakages have to be tolerated.
A tolerable amount of leakage for self-lubricating bearings is such that the bearing does not
need a top-up between the oil change intervals.
The oil can leak from the bearing in two ways:
• Past the labyrinth seals
• Through the split line of the bearing housing.
Sealant
In order to prevent the oil from leaking from the bearing through any split lines, sealant is
applied on the split lines. ABB recommends the Hylomar Blue Heavy sealing compound. Curil
T or other similar compounds can be used as well.
In case the oil leakage is suspected to originate from the bearing housing itself, the following
steps can be taken:
1. Re-tighten the bearing housing
This is especially important during the commissioning of the machine, or if the machine has
been standing still for a longer period, as the parts may set.
If the bearing housing halves are not in a tight fit in respect to each other, the oil might wash
away the sealant from the split line. This in turn will cause oil leakage.
2. Open the bearing housing
The bearing housing can be opened, and new sealant applied on the split lines. Care has to be
taken that no dirt or foreign matter enter the bearing during this procedure. The split lines have
to be completely degreased before a thin layer of sealant is applied.
3BFP 000 050 R0101 REV E