Page 116 - Rollingbearings

B.4 Lubrication
Relubrication of used grease needs to be purged from the Fig. 1
procedures housing, contacting seals must allow for this Relubrication from the side
(consider seal type and seal orientation)
Otherwise, an escape hole should be provided
Select a relubrication procedure that suits in the housing – tubing is not allowed,
the application and the relubrication interval because it can restrict grease escape The
t . SKF recommends one of the following escape hole should be plugged during high -
f
procedures: pressure cleaning
Where a variety of bearing types is used in
• Manual relubrication by replenishment a bearing arrangement, it is common practice
is a convenient procedure. It enables unin- to apply the shortest estimated relubrication
terrupted operation and provides, when interval from the bearings in the
compared with continuous relubrication, a arrangement
lower steady-state temperature.

• Automatic (centralized) relubrication Fig. 2
avoids performance issues related to Relubrication in the centre
over- or under-greasing. This is also
commonly used where there are multiple
points to lubricate, or where access to
positions is dificult, or where equipment is
operated remotely with no local mainte-
nance staff (diagram 3).

• Continuous lubrication
is used when the estimated relubrication
intervals are short because of the adverse
effects of very severe contamination.
Continuous lubrication of applications is
recommended typically with nd values
m
< 150 000 for ball bearings and < 75 000 Relubrication method and impact on performance Diagram 3
for roller bearings In these cases, the initial
Lubrication grease ill for the housing can be from 70% Over-greased = overheating, waste and pollution
to 100 % (depending on the operation con-
dition and housing seal), and the quantity

from the equations for G (Determining
B.4 for relubrication per unit of time is derived Optimal Time
p
lubrication
grease quantity for initial ill and relubrica-
tion, page 112) by spreading the required
quantity over the relubrication interval
Under-greased = wear, premature repairs, high repair cost
There must be provision for the used grease
Manual lubrication Automatic lubrication
to be purged from the housing If an excess

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