Rolling bearings in electric motors and generators
Rolling bearings in electric motors and generators
Rolling bearings in electric motors and generators
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www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071<br />
6 Failure modes <strong>and</strong> corrective actions<br />
Insufficient bear<strong>in</strong>g load/Other damage<br />
Insufficient bear<strong>in</strong>g load<br />
Other damage<br />
When a motor runs without a load,<br />
there is an immense risk that the <strong>bear<strong>in</strong>gs</strong><br />
will become damaged, s<strong>in</strong>ce they<br />
always need to have a m<strong>in</strong>imum load<br />
to function well. The damage will<br />
appear as smear<strong>in</strong>g on the roll<strong>in</strong>g<br />
elements <strong>and</strong> raceways.<br />
It takes time for the <strong>in</strong>itial damage<br />
to develop to such an extent that the<br />
bear<strong>in</strong>g damage can be detected.<br />
Corrective action<br />
Make sure to apply an external load<br />
to the <strong>bear<strong>in</strong>gs</strong>. It is most important to<br />
remember this when us<strong>in</strong>g cyl<strong>in</strong>drical<br />
roller <strong>bear<strong>in</strong>gs</strong>, s<strong>in</strong>ce they are typically<br />
used to accommodate heavier loads.<br />
This does not apply to preloaded<br />
<strong>bear<strong>in</strong>gs</strong> (➔ section “Preload<strong>in</strong>g with<br />
spr<strong>in</strong>gs” on page 47).<br />
Overload from mount<strong>in</strong>g errors<br />
Incorrect mount<strong>in</strong>g methods can significantly<br />
reduce bear<strong>in</strong>g service life.<br />
Damage caused by <strong>in</strong>correct mount<strong>in</strong>g<br />
frequently appears as equally spaced<br />
<strong>in</strong>dentations where the roll<strong>in</strong>g elements<br />
were pushed <strong>in</strong>to the raceways. Over<br />
time, flak<strong>in</strong>g is likely to start from these<br />
<strong>in</strong>dentations (➔ fig 15 ).<br />
These <strong>in</strong>dentations are usually<br />
formed when the mount<strong>in</strong>g force is<br />
applied to the wrong bear<strong>in</strong>g r<strong>in</strong>g <strong>and</strong><br />
the force is transmitted through the<br />
roll<strong>in</strong>g elements; or when a hammer or<br />
similar tool is used to mount a component,<br />
such as a shaft pulley, sprocket<br />
or coupl<strong>in</strong>g.<br />
Cyl<strong>in</strong>drical roller <strong>bear<strong>in</strong>gs</strong> must be<br />
assembled very carefully <strong>in</strong> order not<br />
to damage the bear<strong>in</strong>g. Often times<br />
the two r<strong>in</strong>gs are not properly aligned<br />
dur<strong>in</strong>g the assembly process <strong>and</strong> the<br />
rollers scratch the other raceway<br />
caus<strong>in</strong>g long tranverse streaks<br />
(➔ fig 16 ).<br />
Corrective action<br />
Use appropriate mount<strong>in</strong>g tools <strong>and</strong><br />
methods. In the case of cyl<strong>in</strong>drical<br />
roller <strong>bear<strong>in</strong>gs</strong> the use of a guid<strong>in</strong>g<br />
sleeve is strongly recommended<br />
(➔ chapter 5 “Mount<strong>in</strong>g <strong>and</strong> dismount<strong>in</strong>g<br />
– Mount<strong>in</strong>g of separable<br />
<strong>bear<strong>in</strong>gs</strong>” on page 82.<br />
Transverse smear<br />
streaks from faulty<br />
assembly<br />
6<br />
Fig<br />
15<br />
Fig<br />
16<br />
Mount<strong>in</strong>g error:<br />
Flak<strong>in</strong>g will start<br />
from the <strong>in</strong>dentations<br />
at roll<strong>in</strong>g<br />
element distance<br />
www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071<br />
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