Page 208 - SKF-bearing-housings
P. 208

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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