Sealing solutions
SKF roller bearing units are available with different sealing solutions.
Table 1 provides an overview of the characteristics and suitability of each sealing solution. Details are provided in the following text. This information should be used as a guideline and does not substitute for testing a seal in its application.
TriGard seals
TriGard seals (fig. 1) are standard with inch roller bearing units. These acrylonitrile-butadiene rubber (NBR) seals have the outside surface and seal lips vulcanized to a sheet steel insert. The seal consists of two lips that make contact with the mounting collar or bearing inner ring, and a third, non-contact lip, to protect the seal lips from coarse contaminants. The rubber coated outside circumference secures the seal in the housing and enhances the sealing effect.
Labyrinth seals
As labyrinth seals do not generate friction, bearing units fitted with these seals are capable of relatively high speed operation.
Radial shaft seals (garter spring seals)
Collar-mount units can be supplied with radial shaft seals on both sides, on request (fig. 4). The seals are made of acrylonitrile-butadiene rubber (NBR) and have no metal reinforcement. They sit firmly in the housing bore providing a static seal. The spring-loaded seal lip provides a dynamic seal against the inner ring shoulder.
End plugs
Bearing units mounted at the end of a shaft should have an end plug (end cover) (fig. 5). End plugs for units up to 2 15/16 inches are plastic, while larger sizes are steel. Bearing units with end plugs are identified by the designation suffix Y. For information about the permissible length of the shaft end, contact the SKF application engineering service.