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

A roll motor perhaps.As in pressed in to a tube.Seen bigger ones like that. Mark

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:

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

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mains voltage

Variable speed fan motors - driven by 2 phase bit of electronics and pressed into a plastic fan ?

AWEM

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.

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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

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

I've seen a motor very similar to this as the capstan motor on a very old open reel tape recorder.

The last one I saw was driving the tape loop on a very old dictapfone type machine.

Greg

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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Sorry, missed this out:-

Pancake servo motor, Could be off an old tape drive ?

-- Regards,

John Stevenson Nottingham, England.

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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

Bl**dy big tape drive! To partly answer Greg, there's no detectable cogging.

Another pic at

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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

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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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

Tim, I've printed the picture out and will show it to the couple of motor rewinders when they call within the next two day or so.

I have seen these before but like may jobs no idea what they are off.

The big Bystronic laser cutters have two motors similar to these on the gantry, one either end connected by a jack shaft to stop crabbing. These are servos but they are about 15" diameter and about 8" thick.

-- Regards,

John Stevenson Nottingham, England.

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Nothing wrong with academic interest . I'd quite like to know what it is before it goes in the bin

Cheers Tim

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