Can someone please tell me what this is (electrical)?

http://web.onetel.com/~duttondock/Pictures/motor-1.jpg
http://web.onetel.com/~duttondock/Pictures/motor-2.jpg
It's a sort of 'inside out' motor, the armature/stator is fixed to
what looks like a panel mount. It has two independent windings, each of about 50 ohm DC resistance.
The outer rotor appears to be just a light alloy diecasting, and is rigidly fixed to the 4mm dia spindle. No sign of any permanent magnets.
My best guess is some sort of control device, a current through one winding induces a current in the second which will vary as the outer rotor is turned. Any better or more detailed ideas? I've landed myself with a number of them as part of a job lot.
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
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Tim Leech wrote:

A roll motor perhaps.As in pressed in to a tube.Seen bigger ones like that. Mark www.ems-fife.co.uk
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It's a simple induction motor, driven with three phase it produces a rotating magnetic field that induces eddy currents in the alloy rotor and drags it around. Just the same principle as a common three phase motor but it's an outrunner, i.e. the rotor is on the outside, which makes a compact motor with more torque. Beware that it may not be designed for mains voltage or even 50Hz, what did it come out of?.
Brushless DC motors with this configuration are becoming very common place, the only real difference is that the rotor has a steel ring that is lined with small magnets. By sheer coincidence I bought one this afternoon for a small plane, I hope this convoluted link works:
http://www.modelmotors.cz/index.php?id=en&nc=produkty_vypis&kategorie=m_neodym_ac&id_rady=axi_22&id_produktu=axi_2208_26&nazev_rady=Series%20AXI%2022%20GOLD%20LINE&hmotnost_rady =(25,9%20-%2057%20g)
Greg
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On Sat, 8 Jul 2006 21:14:22 +0100, "Greg"

It didn't come out of anything, other than a cardboard box. I have 15 of them, all in unmarked boxes. Note that I said there are *two* windings, not sure how you run that on 3 phases. Maybe one phase with a shifting capacitor? The outer 'rotor' is finely machined over most of its length, which would support Mark's suggestion that it is intended to be pressed into a tube.
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
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a
rotor and

motor but

compact
mains voltage

15
Variable speed fan motors - driven by 2 phase bit of electronics and pressed into a plastic fan ?
AWEM
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On Sat, 8 Jul 2006 22:06:47 +0100, "Andrew Mawson"

The consensus being it's just an motor I reckon it was designed to be used in two possible ways: as a fan motor, for example, with the hub pressed onto the body; or driving something else via the shaft. I can't see why else the shaft would protrude, and most but not all of the body OD be finely machined. Any load on the body would have to be axial, eg a fan, because of the lack of support.
I doubt that it's for mains voltage, judging by the insulation on the flying leads. When I've got nothing better to do I'll try playing about with one on 24V AC & see what I can get out of it.
Thanks Tim
Please let me know if you have any use for such a thing. I doubt that I have. Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
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On Sun, 09 Jul 2006 09:09:56 +0100, Tim Leech wrote:

I've seen a motor very similar to this as the capstan motor on a very old open reel tape recorder.
--
Regards - Rodney Pont
The from address exists but is mostly dumped,
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The last one I saw was driving the tape loop on a very old dictapfone type machine.
Greg
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It's not clear how many wires there are from the pictures, are there 4 i.e. two isolated windings?. Yes you can get a rotating field with two phases, some aircraft use 2 phase 90 degrees for some motors for example, in this case I would indeed expect a phase shifting cap.

I doubt it, I've seen very similar motors in equipment and the threaded part was mounted through a hold in a chassis plate with a pulley fitted to the shaft.
Greg
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On Sat, 08 Jul 2006 15:57:07 +0100, Tim Leech

Tim, I often get bigger versions of this type of motor in out of fans. The outside presses or bolts into the blade hub.
. -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk /
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On Sat, 08 Jul 2006 23:18:04 GMT, John Stevenson

OK, what's this for?
about 10" dia., appears to be some sort of AC servo motor (3 motor wires & 5 for a tacho or encoder)
Cheers Tim
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On Tue, 11 Jul 2006 22:35:51 +0100, Tim Leech

Sorry, missed this out:-
http://web.onetel.com/~duttondock/Pictures/motor-5a.jpg
Tim Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
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It's hard to tell, can you take more pictures from other angles please, is there any 'cogging' when you turn it that would indicate magnets?. At first sight I would agree it's likely to be a servo motor with feedback, though most are cylindrical with a shaft. At this sort of size servo motors are more often than not 180V as it makes the inverter design simple.
Greg
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On Tue, 11 Jul 2006 22:35:51 +0100, Tim Leech

Pancake servo motor, Could be off an old tape drive ? -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:- http://www.homeworkshop.org.uk /
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On Tue, 11 Jul 2006 22:02:12 GMT, John Stevenson

Bl**dy big tape drive! <G> To partly answer Greg, there's no detectable cogging.
Another pic at
http://web.onetel.com/~duttondock/Pictures/motor-5b.jpg
Cheers Tim
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I'm assuming that the disc with the 12 tapped holes is the fixed part, i.e. the boss with the wires is attached to it?, that's an awful lot of fixing holes so would imply a lot of force somewhere. Is the black part around the edge on the first pic steel laminations?. With no cogging it's fairly certain to be an induction motor.
Greg
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On Wed, 12 Jul 2006 00:21:12 +0100, "Greg"

No, the boss in the centre with 4 holes is the fixed part, all the rest goes around it. That's what prompted me to attach this to the original question. Yes, they are steel laminations. All the other visible bits are Ali.
Cheers Tim
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Tim Leech wrote:

The shape of this is so strange that it must have been made for a very specific purpose but nothing springs to mind, I can't imagine it being of more than academic interest really.
Greg
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wrote:

Nothing wrong with academic interest . I'd quite like to know what it is before it goes in the bin <G>
Cheers Tim
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Tim Leech wrote:

No not at all, in fact if it was mine it would be in bits by now 8-)
Greg
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