Page 50 - SKF-bearing-housings

SKF bearing housings – overview, selection and application recommendations

L ubrication Relubrication

Grease selection Grease escape holes
Grease selection is typically driven by the Bearing arrangements in housings that have
bearing and its operating conditions. The contact seals, e.g. double-lip or four-lip seals,
same grease can be used to fill the housing can be equipped with a grease escape hole to
and lubricate the seal. allow used, excess grease to be purged from
For information about SKF greases, refer the housing. The escape hole should be pos-
to the product information available online at itioned on the side opposite the grease inlet
skf.com/lubrication. The SKF grease selection and if applicable, on the same side as the lock
program LubeSelect, also available online at nut. For long relubrication intervals, it is often
skf.com/lubrication, can be used to select an sufficient to remove the housing cap or cover
appropriate grease. and remove the old grease.
Biodegradable grease for housings with sealed Relubrication via the outer ring
bearings CAUTION: Care should be taken when relu-
If sealed bearings are used, the grease used bricating spherical roller bearings in the non-
to fill the housing and lubricate the housing locating position via their lubrication feature in
seals does not need to be compatible with the the outer ring. There is a risk that the lubrica-
grease inside the bearing. This is a good op- tion groove of the bearing will not be aligned
portunity to use environmentally friendly with the hole in the centre of the housing cap
grease such as SKF LGGB 2. It is a biodegrad- and the lubricant will not reach the bearing.
able, low toxicity grease. For additional infor- This can be the case when narrow bearings
mation about this grease, refer to the product are mounted in housings with a wide housing
information available online at skf.com/ seat, e.g. spherical roller bearings in the 222
lubrication. series mounted in SNL 5(00) series housings,
and the application is subjected to large axial
movements. Under these circumstances, the
Initial grease fill bearings should be relubricated from the side.
If no other requirements exist, the free space
in the bearing should be completely filled with
grease and the free space in the housing
should be filled to 20 to 40% of its volume.
A 40% grease fill is required when bearings
have to be relubricated from the side, while
a 20% grease fill is used when bearings are
lubricated via the outer ring. Fig. 16
For highly contaminated environments and
slow speeds, fill the housing to 70 to 80%. For
the best protection against contaminants, use
the SKF three-barrier solution († page 39).
Higher speeds can require a reduced grease
fill. For additional information, contact the
SKF application engineering service.
Quantities for the initial grease fill are provided
in the individual product chapters.

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