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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Steven Lu ( )
Organization:BAE Systems
Date posted: Tue Apr 23 10:21:25 US/Eastern 2002
Subject: Service life for brushes in brush motors
How to determine the service life for brushes in brush motors? What kind of data do I need to calculate the service life for brushes if there's a way to calculate it?


Subject: Motor Brush Failure
Reply Posted by: B.W.Dudley ( )
Organization: RAC
Date Posted: Tue Apr 23 11:21:11 US/Eastern 2002
To determine the useful life of the motor brushes, you need to collect motor data on the number of operating hours to failure or wearout for the brushes under expected environmental conditions. The sample size should be ten or more to provide some degree of confidence in the analysis results. The analysis technique is shown in our RAC Reliability Toolkit (pages179-188) for mechanical component predictions. Plotting the data using this analysis technique will indicate if the failure trend is deteriorating or improving. If the failure trend is deteriorating, then a Weibull analysis can be applied to determine the time to wearout failure that is, the "L-10" life, i.e. the point in time where 90% of the units have not failed. If you are considering the use of reliability centered maintenance, the L-10 point could be the time to replace all brushes to reduce the number of catastrophic failures.

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