SBD plummer (pillow) block housings and THD take-up housings are supplied with labyrinth seals as standard. They can also be used with sealed spherical roller bearings, and variants are available for taconite heavy-duty seals.
The labyrinth seal consists of a labyrinth ring made of grey cast iron, mounted on the shaft, which forms a multi-stage axial labyrinth with the seal grooves in the housing cover. The number of stages in the labyrinth ring varies with housing size.
In THD take-up housings, the labyrinth rings are locked on the shaft with adapter rings. In SBD plummer block housings, the labyrinth rings are locked in different ways depending on the housing type:
The product tables show how the labyrinth rings are locked for the different housing designs for:
- SBD plummer block housings for bearings on an adapter sleeve and a plain shaft
- SBD plummer block housings for bearings on an adapter sleeve and a stepped shaft
- SBD plummer block housings for bearings on a cylindrical seat and a stepped shaft
- SBD plummer block housings for bearings on a cylindrical seat and a multi-stepped shaft
Adapter rings are supplied with the housing when needed. The adapter ring is identified by the prefix PSBD followed by the size (shaft diameter) in millimeters uncoded, e.g. PSBD 170. Adapter rings are listed in table 1.
In typical applications, the bearing and housing are completely filled with grease. Excess grease enters the labyrinths and improves the sealing effect. Most THD take-up housings and SBD plummer block housings have ducts to supply grease directly to the seals.
Seal characteristics are listed in table 2.