M = Metal Case or Re-inforcement
B = Cork Sealing Element
F = Felt Sealing Element
L = Leather Sealing Element
R = Synthetic Rubber Element (Nitrile)
Si = Silicone Rubber Element
Vi = Viton Rubber Element
Py = Polyacrylic Rubber Element
S = Steel Case or Re-inforcement
B = Brass Case or Re-inforcement
R/H = Right Hand Rotation (Helix or Spiral)
L/H = Left Hand Rotation (Helix or Spiral)
Bi/D = Left or Right Hand Rotation (Bi-directional, Helix or Spiral)
M/F/L = Metal Case (or Re-inforcement) with (one) Felt and (one) Leather Sealing elements
M/Si(4B)L/H = Metal Case (or Re-inforcement) with (one) Silicone Sealing element, 4B seal design, Left Hand Rotation
Where it is necessary to replace a bearing or to disturb a seal, a new seal of the correct type and dimensions should be fitted. This is essential in the case of seals that protect the bearings in the hubs (front and rear). If these leak, braking efficiency is reduced. The three key dimensions as indicated in the search facility are:
The diameter of the housing into which the seal fits.
The diameter of the shaft on which the seal runs.
The width of the seal.
There are two main types of Oil Seal:-
Shafts should be checked for scoring. Score marks or burrs should be carefully removed.