|Split Bearing Lubrication is to prevent metal to metal contact between bearing components, prevent wear and protect against corrosion. Two methods of bearing lubrication are normally employed grease and oil. In the case of SRB Split Bearings grease bearing lubrication is most often employed.|
Bearings greases can be used to lubricate SRB split roller bearings under most normal conditions. Grease is the preferred method of bearing lubrication because it can be more easily retained within the bearing enclosure and housing, the latter simplifying sealing arrangements. Greases are essentially oils thickened usually with a metal soap, a third ingredient are additives such as rust inhibitors, or extra pressure additives. The oils employed may be mineral or synthetic depending upon the application.
The re-lubrication intervals will be dependent on the prevailing operating conditions. Greases age and oxidise due to a number of considerations these include load, speed, temperature, cleanliness, presence of water and even airflow through the bearing.
For retained type bearings, initial re-lubrication intervals for guidance purposes would be 2 - 4 weeks with 3 - 6 mls added. For expansion type bearings, initial re-lubrication intervals would be 3 - 4 months with 3 - 6 mls added. More accurate intervals and quantities should be established from observations taken during bearing operation.
If re-lubrication can be carried out whilst the bearing is in operation, this will allow for even distribution of the grease. This means of re-lubrication should only be undertaken if it is safe to do so.
Oil Bearing Lubrication
SRB split roller bearings are rarely lubricated with oil. In cases where oil is selected as a means of lubrication, then special consideration must be given to the bearing housing design and sealing.
There are three principal methods of oil lubrication:
- Oil Sump:
The oil sits in the bearing housing at a level approximately ½ way up the bottom dead centre rolling element. Oil circulation around the bearing is then provided via the bearing rotation agitating the oil sump. It is very important to provide a sufficiently dimensioned oil sump as too small a volume will result in increased frequency of oil change and elevated operating temperatures.
- Oil Mist:
An oil/air mist is injected into the bearing via nozzles, normally a total oil loss system, this provides extremely high speed capability at high cost.
- Oil Circulation:
Oil is circulated into the bearing housing assembly from an external oil sump. This allows the oil to be cooled and filtered, additionally an external oil sump normally allows for a higher volume of oil. Whilst being a more optimum solution, specialist housing designs must be provided. There is also a cost and space requirement to this system.