Oil Leakage Of Sleeve Bearings; Oil - ABB AMA Series Manual

***Following chapters for bearing type: Sleeve bearing

8.2 Oil leakage of sleeve bearings

8.2.1 Oil

3BFP 000 050 R0101 REV E
The construction of a sleeve bearing is such that it is very difficult to avoid oil leakage
completely, and therefore small amounts of leakage should be tolerated.
However, oil leakage can also appear because of reasons other than the bearing design, such as
incorrect oil viscosity, overpressure inside the bearing, underpressure outside the bearing, or
high vibration levels at the bearing.
If excessive oil leakage is noted, please check/verify the following:
• Verify that the oil used is according to specifications
• Re-tighten the bearing housing halves, and the labyrinth seal cover. This is especially
important, if the machine has been stopped for a long time
• Measure the vibrations of the leaking bearing in three directions under full load. If the
vibration level is high, the bearing housing might "loosen" just enough to permit the oil to
wash away the sealant between the housing halves
• Open the bearing, clean the surfaces and apply new sealant between the bearing housing
halves
• Verify that there is nothing, which might cause low pressure next to the bearing. A shaft or
coupling cover can for instance be designed so that it will cause low pressure near the
bearing
• Verify that there is no overpressure inside the bearing. Overpressure may be entering the
bearing through the oil outlet piping from the oil lubrication unit. Apply breathers or vents
to the bearing housing as to relieve the overpressure from the bearing
• In case of a flood bearing lubrication system, check that the slope of the oil outlet pipes is
sufficient.
If excessive oil leakage is found even after all of the above and below mentioned things have
been checked and verified, please fill in the form Oil Leakage's at RENK Sleeve Bearings and
send it to the after sales and market support department.
In order for the bearings to function as expected, the oil has to meet certain criteria like viscosity
and cleanliness, see Chapter 7.5.2.2 Control of the lubricant and Chapter 7.5.2.3 Recommended
control values for the lubricating oil.
Viscosity
The bearings are designed to run with an oil of a certain viscosity, which is mentioned in the
documentation provided with the electrical machine.
Incorrect viscosity will lead to lubrication failures, and can damage the bearings, as well as the
shaft.
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