Hello,

do any one know houw many running houre is equivalent to one shutdown/startup.

this is to have an accurate idea about the bearing life of rolling bearing that is frequently stoped and stared-up.

Many thanks.
N.T

N.T.

As such I believe there is nothing like equivalent hours. For frequent shutdown/startup general recommendation from bearing manufacturers is the use of AW or EP additives. Use anti-wear for lightly loaded bearings, and EP for medium and heavily loaded bearings.

You could try to model the startup/shutdown conditions by using average speed/load and time during the startup/operation/shutdown conditions. For example:
If the bearing is running at 1500 rpm you could do something like this:

Speed (rpm) load (N) time (%)
1600 3000 90%
1200 3000 2%
900 3000 2%
600 3000 2%
300 3000 2%
50 3000 2%

You can use this data and feed it to a bearing life calculation program. At least one bearing manufacturer has it on the internet.

Hope this helps.

Alex