Attachment to support surfaces

Holes to take attachment bolts are cast in the housing base of all SKF plummer block roller bearing units. The holes are elongated to allow subsequent adjustment of housing position.
Units in the SYNT, SYE and SYR series have two holes cast into the base for attachment bolts. Housings in the SYE series with designation prefix F have four holes.

Attachment bolts

To attach the bearing units to their support (mounting) surfaces, SKF recommends using fasteners such as hexagon headed bolts in accordance with ISO 4014:1999. For radial loads that act in the direction of the support surface, strength class 8.8 bolts can be used. If the loads are particularly heavy or act in other directions, strength class 10.9 bolts are preferred.

Dowel pins

In addition to the attachment bolts, SKF recommends using dowel pins to pin plummer block bearing units to their support surfaces under the following conditions:
  • if the direction of the load lies between 55 and 120° (fig 1)
  • if the load acts parallel to the support surface and exceeds 5% of the breaking load P180° (see the section Load carrying ability)
For SKF ConCentra roller bearing units in the SYNT series, appropriate positions for these dowel pins are indicated by dimples cast into the housing feet. Details about the position and size of the dowel pin holes are listed in the table.

Support surface requirements

To maximize the service life of an SKF roller bearing unit, SKF recommends using a support (mounting) surface with a surface roughness Ra ≤ 12,5 μm and flatness tolerance that meets IT7 specifications.