Bearing Lubrication

Grease pack bearings are preferred because they are sealed, maintenance free, and do not require a service line routed into the slip ring location. However, this typically has a lower speed capability. Also, environmental considerations such as temperature and pressures at the slip ring location need to be considered. High ambient temperatures may preclude the use of grease pack bearings, and locations where pressure differentials exist need to be carefully considered.

Oil air mist installations are more complicated because they require external lubrication systems, additional service lines, and venting of the bearing cavity. However, they allow the slip ring to operate at its maximum speed and in elevated temperature and pressure locations. Thermocouples are built into the bearing housing and placed in direct contact with the outer bearing race. This allows continuous monitoring of the bearing temperature so the predetermined maximum temperatures are not exceeded.