Sealing Options for Self-Lubricating Bearings

Contamination is one of the most common causes for the failure of journal bearings. Metal bearings combat this problem with the use of grease zirks and maintenance schedules that are imposed on the end users. Grease is needed on a regular basis throughout the life of the machine to purge contaminates. This is a result of the inability of the bearing surface to ingest the particulate. Self-lubricated bearing manufactures typically design bearing liners that are soft enough to ingest contaminants. Each manufacturer of this type of bearing uses a different construction to try to best solve this problem. In the case of PolyLube™ Fiber and MRP bearings, the liner architecture is designed with macroscopic pockets that allow debris to be ingested without compromising the transfer of PTFE from the bearing ID to the shaft surface. No matter how good the design of any bearing, there is still a limit to the amount of contamination that can be ingested. After this limit has been reached, damage to the shaft and bearing will continue until the joint is inoperable. Some typical applications that have environments that typically are highly contaminated are track roller systems used on off-highway equipment, joints in lower areas on earth moving equipment such as bull dozers and skid-loaders, and linkage systems in seeding and fertilizing equipment.