Sealing solutions
SDAF housings 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. Table 2 and Table 3 provide an overview about which seals fit what housing. PosiTrac, PosiTrac Plus and contact seals are not available for SDAF extended range housings.
Labyrinth seals
Labyrinth seals are the standard sealing solution for all SDAF housings. They form a multi-stage labyrinth seal with the seal grooves in the housing. If operating conditions require it, the sealing effect can be enhanced by filling the cavity between the housing and labyrinth ring with grease.
Labyrinth seals for SDAF housings
SDAF housings are supplied with either standard labyrinth seals (fig. 1) (designation LER) or Posi-Trac labyrinth seals (fig. 2) (designation LOR). Both are made of aluminium. The Posi-Trac labyrinth seals have an additional O-ring made of acrylonitrile-butadiene rubber (NBR) to make the labyrinth ring rotate with the shaft. Whether the standard labyrinth seal or the PosiTrac seal are supplied depends on housing size.
Labyrinth rings with an internal contact element
The contact element is located in the seal groove in the housing. It can be mounted either for best contaminant exclusion (fig. 4) or for best lubricant retention (fig. 5). When the contact element is mounted for best contaminant exclusion, the sealing effect can be enhanced by filling the seal cavity with grease. The designation for the contact element is B 10724 followed by a size code, for example B 10724-122.
Taconite heavy-duty seals
To further protect against the ingress of contaminants, SKF taconite seals have a grease fitting to purge old grease and any trapped contaminants from the seal cavity, through the outboard seal.
Taconite heavy-duty seals are available for all smaller SDAF housings, but not all housings in the extended range.
Bolt-on taconite seals
Bolt-on taconite seals consist of a split cast iron auxiliary cover, a split radial shaft seal, a grease fitting and all mounting hardware. Bolt-on taconite seals were developed to accommodate the SDAF extended range housing and provide the equivalent sealing protection as the other taconite heavy-duty seals. All bolt-on taconite seals are custom manufactured during the production of the housing and should be ordered together with the housing.
Bolt-on taconite seals are available for all SDAF extended range housings. For SDAF extended range housings, the designation suffix T indicates bolt-on taconite seals, e.g. SDAF 23272 KAT x 13 7/16.
Contact seals
Contact seals are spring-loaded radial shaft seals made of NBR and fit into the seal groove in the housing (fig. 8). Contact seals are available for shaft diameters 6 7/8 in. and larger, where PosiTrac seals are not available. The designation for contact seals is B 9784 followed by a size code, e.g. B 9784-130.
End plugs
Housings at the end of a shaft should have an end plug (end cover) that fits into the seal groove in the housing (fig. 9). The plug consists of a metal plate with a strip made of acrylonitrile-butadiene rubber (NBR). Details of the permissible length of the shaft end are listed in the product tables for bearings on an adapter sleeve and for bearings with a cylindrical bore. End plugs for SDAF and SDAF extended range housings are identified by the series designation EPR or X 5217, followed by the size identification.
