Rolling bearings in electric motors and generators

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4 Lubrication and sealing
Relubrication intervals
Deviating operating conditions
and bearing type
Operating temperature
To account for the accelerated ageing
of grease with increasing temperature,
SKF recommends halving the intervals
obtained from the diagram 3 for every
15 °C increase in operating temperature
above 70 °C, remembering that
the high temperature performance limit
for the grease (➔ diagram 2 , page 60,
HTPL) should not be exceeded.
The relubrication interval t f may be
extended at temperatures below 70 °C
if the temperature is not close to the
lower temperature performance limit
(➔ diagram 2 , page 60, LTPL). A total
extension of the relubrication interval
t f by more than a factor of two is never
recommended. In case of full complement
bearings and thrust roller bearings,
t f values obtained from diagram
3 should not be extended.
Moreover, it is not advisable to use
relubrication intervals in excess of
30 000 hours.
Diagram
3
Relubrication intervals at operating temperatures of 70°
t f , operating hours
50 000
4
10 000
5 000
1 000
C/P ≥ 15
500
C/P ≈ 8
C/P ≈ 4
100
0
200 000 400 000 600 000 800 000
bearing factor b f × n × d m
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