Page 709 - SKF-bearing-housings

Design considerations

Operating temperature Attachment bolt recommendations
The permissible operating temperature is lim- In typical applications, 8.8 class (SAE J429,
ited by the seals († table 1, page 699) and Grade 5) hexagon head bolts can be used
the lubricant († table 13, page 706). together with washers. If the load does not act
The housing material does not have any perpendicularly toward the base, it may be
additional temperature limits, except for very necessary to use stronger, 10.9 class
low temperature applications where impact (SAE J429, Grade 8) bolts.
strength could be a factor. SKF inch roller bearing units can withstand
The housing paint is heat resistant up to loads resulting from tightening the attach-
175 °F material temperature or 210 °F ambi- ment bolts to the torque values recommended
ent temperature. by bolt manufacturers. They are valid for oiled,
When temperatures outside the permissible but otherwise untreated, thread surfaces. SKF
range are expected, contact the SKF applica- cannot guarantee that tightening to the rec-
tion engineering service. ommended value will provide sufficient
anchoring. Make sure that attachment bolts,
dowels or stops, and a sufficiently strong sup-
Operating speed port can accommodate all occurring loads.
The speeds at which SKF inch roller bearing
units can be operated depend on the sealing
solution in the bearing unit. For bearing units
fitted with TriGard or radial shaft seals, the
limiting speeds are based on the permissible
circumferential speed at the seal lips
(† table 1, page 699). For bearing units fit-
ted with labyrinth seals, the limiting speeds
are imposed by the bearing size and grease.
Guideline values for the limiting speeds are
listed in the product tables.

Shaft specifications
For SKF ConCentra units, SKF recommends
using the shaft tolerances listed in table 11
for the bearing seat. For collar-mount units,
use the values listed in table 12.
A small lead-in chamfer should be machined
at the shaft end to facilitate mounting.

Table 11 Table 12
Shaft tolerances for SKF ConCentra units Shaft tolerances for collar-mount units
Shaft diameter Tolerance Shaft diameter Tolerance
from to high low from to high low
in. in. in. in.
1 7 /16 1 1 /2 0 – 0.003 1 7 /16 1 15 /16 0 – 0.0005
1 11 /16 2 1 /2 0 – 0.004 2 4 15 /16 0 – 0.001
2 11 /16 4 0 – 0.005
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