Page 168 - SKF-bearing-housings
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Split plummer block housings SNLN 30 series

             Felt seals                          steel end covers should be used. These can be
             Felt seals are simple and effective. At circum-  cut from sheet steel and placed in the seal
             ferential speeds above 4 m/s, a small gap   groove. Use a hollow silicone rubber cord to
             forms between the felt and shaft, transform-  hold the cover in place.
             ing the contact seal into a non-contact, gap-  For housings from size 3034 to 3056, the
             type seal.                          end covers are made of grey cast iron and are
                                                 suitable for operating temperatures from –50
                                                 to +200 °C (–60 to +390 °F). They are inserted,
             Labyrinth seals                     together with a hollow silicone rubber cord, in
             For applications where there are high speeds   the housing seal groove.
             or extreme temperatures, SKF recommends   Details of the permissible length of the shaft
             using labyrinth seals. Labyrinth rings, mounted   end are provided in table 4.
             on the shaft, form a multi-stage labyrinth seal
             with the housing seal grooves.   Hollow, silicone
             rubber cords, supplied with the rings, hold the  Using sealed bearings
             rings in place on the shaft.
                                                 Using sealed bearings in housings with stand-
                                                 ard seals is a good solution for highly contam-
             Taconite heavy-duty seals           inated environments. The sealed bearing
             For bearing arrangements that must operate   together with the housing seal and grease
             under highly contaminated conditions, such as   provide three layers of protection († SKF
             those encountered in mining, taconite heavy-  three-barrier solution, page 39).
             duty seals, which can be filled with grease, are   SNLN 30 housings can be used together
             recommended. Grease enhances the sealing   with SKF sealed self-aligning bearings. When
             effect and extends the service life of the seals.   using taconite heavy-duty seals, a sealed
             Taconite heavy-duty seals are labyrinth seals   bearing does not enhance the sealing effect
             combined with a V-ring seal. The labyrinth   during operation, but still protects the bearing
             ring is solid but the main body of the seal is   against contaminants during mounting.
             split.
               SNLN 30 housings from size 3024 to 3032
             accommodate taconite seals with a radial
             laby rinth. SNLN 30 housings from size 3034
             to 3056 accommodate solid taconite seals
             with an axial labyrinth. Both can be relubri-
             cated via a grease fitting in the main body of
             the seal.
               The axial movement of the shaft relative
             to the housing is limited to ±1,5 mm for shaft
             diameters ranging from 110 to 150 mm,
             ±2 mm for shaft diameters ranging from
             160 to 200 mm and ±4 mm for larger shaft
             diameters.

             End covers
             Housings at the end of a shaft should have an
             end cover that fits into the seal groove in the
             housing.
               For housings from size 3024 to 3032, the
             end covers are made of plastic and are suitable
             for operating temperatures from –40 to
             +110 °C (–40 to +230 °F). For applications
             where temperatures exceed 110 °C (230 °F),

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