• have the same features and internal design as open spherical roller bearings
• are available with a cylindrical bore as standard
• are supplied grease lubricated and should not be washed
• are equipped with an annular groove and three lubrication holes in the outer ring, except for those with the designation suffix W
• are fitted with a contact seal, on one or both sides, made of one of the following materials:
  • sheet steel reinforced NBR (designation suffix CS or RS)
  • sheet steel reinforced HNBR (designation suffix CS5 or RS5)
  • sheet steel reinforced FKM (designation suffix CS2)

The seals are fitted in a recess on the outer ring and seal against the inner ring. On larger bearings, the seals are fixed by a retaining ring.

Bearings sealed on both sides are lubricated for the life of the bearing and are virtually maintenance-free (→ Grease life for sealed bearings). They are filled with one of the following greases:

• SKF LGEP 2 grease (designation suffix VT143) as standard
• SKF LGHB 2 grease (designation suffix GEM) or LGWM 2 grease (designation suffix GLE) on request

Grease life for sealed bearings
The grease life for sealed bearings is presented as L₁₀, i.e. the time period at the end of which 90% of the bearings are still reliably lubricated, and depends on the load, operating temperature and speed factor. It can be obtained for bearings with standard SKF LGEP 2 grease (designation suffix VT143) from:

• for light load (P ≤ 0,067 C)
• for normal load (P ≤ 0,125 C)

The grease life is valid under the following operating conditions:

• horizontal shaft
• inner ring rotation
• operating temperature within the green temperature zone of the grease
  
• stationary machine
• low vibration levels
• load ratio F_a/F_r ≤ e
  
• rotational speed below the limiting speed
  

For other operating conditions, the grease life can be estimated by multiplying the relubrication interval for open bearings by a factor of 2,7.

Relubrication of sealed bearings
When the required service life is longer than the grease life, the bearings may require relubrication.

Further downloads, documentation available on request
Source: SKF
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