Prestolite MTC-4001 Series-wound DC Motor
It squeals. We've done everything we could think of, and it still squeals under heavy load. So we replaced the bearings, one of whom was iffy.
Then we finally heard it squeal, while stalled.....
The rotor is slipping on the shaft. Has anyone ever seen such before? We're going to pull it tomorrow and crack it open. Maybe a missing key?
Never seen a keyed shaft on a motor. Have seen splined, however. Is there any way the shaft could have been moved? Like dropping the motor on the shaft!
Paul
We bought it used and allegedly rebuilt, so donno...
I applaud your sarcastic wit.
You may need an experienced motor rebuilding expert's advice or services.
I've worked around and seen some big industrial motors but never heard of a keyed rotor. I've seen small and large motor shafts with deep straight knurls (sorta splined, as Paul suggests) but none with any sort of secured-in-place-after-assembly sort of devices/hardware.
I'm assuming a wound laminated rotor, and I believe any shifting of the segments would be likely to result in rubbing of the windings, and possibly shorted turns.. I'm surprised that this hasn't already occurred. Maybe the segments are keyed to each other, but that would be unusual, I think.
I'd be interested to learn more about the project.
If it's been slipping, it may be out of sync with the commutator. DC, right? That could cause some other problems. I can remember a few details from some old motor rewind books, one of the older sorts of traction motors had laminations held on with big nuts and washers, commutator bars and mica, ditto. Unfortunately I don't remember any other details. You may have to get the thing to a motor shop to get it straightened up. And construction practices have certainly changed since the '20s or '30s when that book was written.
Stan
The armature of the motor is shrunk onto the motor shaft. Apparently it is a little loose. I have cut rotors for big 100 hp motors that have the rotor shrunk onto the shaft. the get a truing cut on the rotor after it is shrunk onto the shaft. I would imagine you could press out the shaft part way and then put loctite or other adhesive on it and press it back in.
John
Pressed the shaft out today. No splines except for fan and ??under commutator?? plastic/rubber.
Inside is 5-6 quarter-circle pieces with gap that is obviously to allow contraction/expansion. [Sorry - no picture "down the tunnel" showing same.
Shaft was clearly slipping; visible markings.
Plan to call Permetex and get advice on best goo to use to bond shaft to armature.
RCM advice??
Red high strength loctite?
I'm sure the operating temp under it's normal load will also need to be known, some locking adhesives can't take much before softening.
Is there any place you can drill for a roll pin or woodruff key or other mechanical means of attachment?
MikeB
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.