NTN bearings have a double-sealing construction that comprises an oil-resistant rubber seal and a flinger.
The double sealing construction boasts a sealing performance that is much more reliable than standard seals since the ingress path for dust is long, and because excess grease, which purges between the seal and the flinger when the bearing is in operation, serves as a seal.
Bearing Unit with Dust Cover
NTN offers bearing units with external dust covers. Available either in pressed steel or cast iron, the dust cover and sealing mechanism provide extra protection for the bearing unit in heavily contaminated environments. Bearing units with dust covers can withstand the most severe environments in flour milling, steel making, casting, plating, and chemical plant applications where heavy dust and moisture are present. These units can also be used on outdoor equipment, such as construction and transport machinery.
The rubber seal in the dust cover has two lips that contact a shaft, as shown in Fig.A and B. The grease between the two lips not only enhances sealing performance but also lubricates the contacting faces of the lips to the shaft.
The triple-sealed bearing is provided with a bearing seal having three lips. The special seal offers reliable dust and water-proofing performance superior to standard bearings and offers longer bearing life. (Detailed information on triple-sealed bearings)