Brush wear forecasting
Vol. 19 #1, Feb. 1992
DC drive motor brush failure forecasting can be especially useful if you do not have electronic brush wear monitors.
At each PM, measure and record brush length (in 32nds), date, and hourmeter information. With this you can (longhand or with spreadsheet) calculate the nominal machine run timer per day and brush wear rate.
See also
DC drive failure
Drive motor start up
Threaded commutators