Sealing solutions

SNL plummer (pillow) block housings in the 30, 31 and 32 series are available with different standard 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.

Labyrinth seals

For applications where there are high speeds or extreme temperatures, SKF recommends using labyrinth seals (fig. 1). Labyrinth rings, mounted on the shaft, form a multi-stage labyrinth seal with the housing seal grooves. A hollow, silicone rubber cord, supplied with the ring, holds the ring in place on the shaft.

Taconite heavy-duty seals

For shaft-bearing combinations that must operate under highly contaminated conditions, such as those encountered in mining, taconite heavy-duty seals (fig. 2), which can be filled with grease, are recommended. Grease enhances the sealing effect and extends the service life of the seals.
Taconite heavy-duty seals are labyrinth seals combined with a V-ring seal. The inner ring of the labyrinth seal is solid but the outer ring is split. They can be relubricated via a grease fitting in the main body of the seal.
The axial movement of the shaft relative to the housing is limited to ± 2 mm for shaft diameters up to 200 mm and ± 4 mm for larger shaft diameters.

Seals for oil lubrication

Seals for oil bath and circulating oil lubrication systems (fig. 3) require a modified housing, and are therefore supplied together with the housing.
The oil seals consist of a stationary part, which is fitted in the housing, and a labyrinth ring that rotates with the shaft. The labyrinth ring is held in place by two hollow silicone rubber cords, which also help to prevent oil leakage (fig. 4).
SNL housings with oil seals are identified by the designation suffix TURT for spherical roller bearings and TURA for CARB toroidal roller bearings. The seal by itself is designated TSD .. U.
SNL housings for inch shafts can also be used for oil lubrication. For additional information, contact the SKF application engineering service.

End covers

Housings at the end of a shaft should have an end cover (fig. 5) that fits into the seal groove in the housing.
End covers, which are made of grey cast iron, are installed with a hollow, silicone rubber cord that holds the cover in place. End covers are available in two variants, one for grease lubrication and one for oil lubrication.
Details of the permissible length of the shaft end are listed in table 2.
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