Page 208 - SKF-bearing-housings

Split plummer block housings SNL 30, 31 and 32 series

Locating and non-locating The limits for P 0° apply only when the
bearing positions housing is not supported over its entire base.
SNL housings can be used for both the locating The load P a is the axial breaking load of the
and non-locating bearing positions. housing. If the incorporated bearing is mounted
For smaller sizes, the housings are machined on a sleeve, check the permissible axial load
standard for bearings in the non-locating for the sleeve.
position. Bearings in the locating position as For housings made of spheroidal graphite
well as CARB toroidal roller bearings must cast iron, the values obtained from tables 5
be secured in the housing on both sides with and 6 should be multiplied by a factor of 1,8.
locating rings. Appropriate locating rings are
listed in the product tables. Safe loads
Ho usings from sizes 3076, 3168 and 3264 In some countries, safe loads are used instead
upwards are supplied in two designs: of breaking loads. Approximate safe loads are
listed in table 6 on page 207. These guideline
• Housings with the suffix F have a bearing values have been established using accepted
seat that matches the bearing width. These engineering practices, taking safety, ultimate
housings should be used for spherical roller tensile strength of the materials and working
bearings in the locating position and CARB stresses into account. They reflect a safety
toroidal roller bearings. factor of 5 against fracture, and a min imum
• Housings with the suffix L have a bearing factor of 2 against cap bolt yield.
seat that is wider than the bearing. These
housings should be used for spherical roller Additional housing support
bearings in the non-locating position. The When the housing is subjected to loads acting
possible axial displacement is at least 20 mm. parallel to the support surface, it may be
neces sary to pin the housing to the support
surface or to provide a stop to counter the
Load carrying capacity load. When loads act at angles between 55°
SNL housings are intended for loads acting and 120°, or when the axial loads are greater
perpendicularly toward the support surface. than 5% of P 180° († table 6 on page 207), the
If the housing is supported over its entire base housing should be pinned to the support sur-
and the loads are purely perpendicular, loads face or a stop should be provided to counter
are limited only by the bearing. If loads acting the load. The dowel pins or stop should be suf-
in other directions occur, or if the housing is ficiently strong to accommodate the loads act-
not supported over its entire base, be sure ing parallel to the support surface.
that the magnitude of the load is permissible Recommendations for the position and size
for the housing, the cap bolts and the attach- of the holes to accommodate dowel pins are
ment bolts. When housings are subjected to provided in table 11 on page 219.
cyclic loads or dynamic imbalance, contact the
SKF application engineering service.

Breaking loads and safety factors
Guideline values for the breaking loads P for
housings made of grey cast iron are listed in
table 5 on page 205.
To obtain the permissible load for a housing,
the appropriate breaking load value should
be divided by a factor based on the safety
requirements. In general engineering, a safety
factor of 6 is typical († Load carrying capacity,
page 44).
The permissible load can only be exploited if
the cap bolts are tightened at least to the
torque values listed in table 7 on page 210.

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