1988 vintage Indramat MDC 10.20F to be precise...typical on Maho mills from the mid to late 1980's. This motor hasn't turned in nearly a decade so beyond me what the conditions were that cause it's demise....but knowing where it was positioned I suspect coolant ingress and internal corrosion issues.
I noticed when I turn the shaft by hand one can feel a slight "bump" sensation every quarter turn...barely noticable but seems not quite right. When I hook the motor to 30 VDC it will turn 1/4 revolution (if the shaft happened to be in the right spot) and stop. I can "help" it by turning by hand, but it still stops every 1/4 turn and the "bump" feeling is way more noticable under power.
I can tell you what it's not.... it's probably not bearings, it's definitely not related to brushes on armature or tachogenerator (had them all out and still felt the same).
Literature on the motor says other than tachogen maintenance, these motors "must not be dismantled" as this may lead to their partial demagetization. True ? If so, any way to avoid demagetization if one is careful ? Regardless, what the heck might be wrong with this thing ?
I noticed when I turn the shaft by hand one can feel a slight "bump" sensation every quarter turn...barely noticable but seems not quite right. When I hook the motor to 30 VDC it will turn 1/4 revolution (if the shaft happened to be in the right spot) and stop. I can "help" it by turning by hand, but it still stops every 1/4 turn and the "bump" feeling is way more noticable under power.
I can tell you what it's not.... it's probably not bearings, it's definitely not related to brushes on armature or tachogenerator (had them all out and still felt the same).
Literature on the motor says other than tachogen maintenance, these motors "must not be dismantled" as this may lead to their partial demagetization. True ? If so, any way to avoid demagetization if one is careful ? Regardless, what the heck might be wrong with this thing ?