[Tig]

Hi guys,

I wonder if any one out there can identify this motor I bought on ebay.
Yes, I know there is a plaque in the photo, but that's not the motor I received.
The seller stated that "the motor had been checked out and was and in good working condition".
What I received was nothing like the photo. Not only was it not in working condition, there was no information on the motor at all.
I was able to source brushes by size and the shape of the brush holder.
The motor is now running ok, but I don't know what Voltage or how much current it will take. I did contact the seller and he replied with the following:

"ok here is the best I can tell you.the information tag is printed very
lightly and very hard to read. but the rpm is 4500,ser 03084671 these wher
clearly printed. type79a-48-45k6jpihr this is best guess as the label is so
lightly printed"

Any help identifying this motor would be greatly appreciated.
Thanks,
Tig

[Al_The_Man]

It appears to be a Getty's or at least the same style if a knock-off.
If the sellers was right about the 4500rpm, BTW, that is around the very top end rpm for a motor of that style.
Going by the 4500rpm, there is two ways you can discover the max voltage.
Either by back feeding the motor at a known rpm and measure the generated voltage and extrapolate the voltage at 4500rpm, or feed a known voltage into the motor and measure the resulting rpm and again extrapolate.
It appears to be around the 1.5~2hp mark, going by the photo.
I have posted some info before for detecting other specs, either search here or I can did it up again and repost.
Al.

[Tig]

Thanks Al.

Anyone else familiar with this motor?

[mike_Kilroy]

Thanks Al.

Anyone else familiar with this motor?

there seem to be two nametags on the motor. if u want help identifying them why not write down ALL the words written on those nametags for us? they r unreadable in the photos

[Tig]

Mike,
Perhaps I was not specific enough.
The picture posted was the original picture from the ebay auction. There were no such information plaque (nametags) on the motor that I received.
Hence: "there was no information on the motor at all"
It was a classic case of the old bait and switch.

Tig

[mike_Kilroy]

ah. sorry, I misunderstood. guess Al's data is about best advice u can get then. good luck

[vger]

did the motor you received have the encoder and brake like the one pictured?

[Tig]

Hi Vger,
Yes it did. The encoder was a Sumtak M# 0105-0421 600p/r.
I am trying to salvage the motor because of the working 24V brake which just happens to fit an 8:1 gearhead I had laying around.
It should make a nice compact Z-axis unit if it specs out as stated.
The motor I received was certainly not in the the good condition of the one pictured in the auction. Nor was it working.
The brushes had worn down to, and in one case through the copper rivets. The brush screw caps were broken or missing.
I was eventually able to find brushes and caps that fit. At this point I have only tested it with 24VDC. It seems to run smoothly, so I am now ready to hook it up to a servo drive.
The vendor believed it is a 90V motor, but I'm not sure. I also need the HP rating to safely setup the Amps in the drive.
Like Al said, one can find Motor voltage by measuring the RPM for a given Voltage, and then extrapolate for the top RPM.
I will check the RPM at 90V with a strobe light, but guessing at the RPM at 24v I seriously doubt the stated 4500 RPM.
Anyway, work calls.
Thank you for your interest.
Tig

[Al_The_Man]

Any DC motor that has worn the brushes down to the springs requires a very close inspection, carbon build up, commutator wear etc.
If it is adifferent motor then the max rpm may not be correct, most motor of that size/type were 2500rpm average.
Here is one of the procedure sheets for , I have a couple more I will post.
Al.

[mike_Kilroy]

since u r going to run it at higher voltage and measure rpm, u will have the motor Kb or Kv (volts/Krpm) rating. this is the same as the motor Kt (torque/amp) but different units. Hence u will have the motor Kt. Now any pm motor with a given physical size will have a very similar constant torque rating. so if u were to list here the motor diam and length of the motor portion of the motor (from say front endbell to brushes), folks like us and AL can tell u what a similar size motor would be rated in torque. since u will have the motor Kb then we can convert this to #-in/amp units and with the motor similar size torque rating, tell u a close approx. of the motors current rating.

if u wanted, u then could verify it by clamping motor shaft and putting in this motor current while measuring the motor temp; actually I would put in say 1/5th this current to be safe, then raise it slowly while watching temp until it got to a temp I was willing to run at (typically 150F?). ur size motor will have around a 15 minute time constant. that is the current rating. use double this as the peak rating. u also can do this by itself to see current rating w/o the benefit of the Kb cross check, but since u will get Kb too, why not use it too.

[Tig]

Al,

the printed material is always helpful.
The commutator is scored, but not to badly. I would chuck the motor if it wasn't for the nice brake on it.

Vger,

The motor diameter is 3" and the length from the center of the brush retainer screw cap to the motor brake interface is 3.2".
There are four brushes each measuring 0.237" x 0.197". The supply wire gauge is 16 AWG

Thanks
Tig

[mike_Kilroy]

....The motor diameter is 3" and the length from the center of the brush retainer screw cap to the motor brake interface is 3.2".
There are four brushes each measuring 0.237" x 0.197". The supply wire gauge is 16 AWG...
Tig

make motor length then 2.5" long (it is the solid barrel for the actual motor). typical 3" dia motor 2.5" long would be about .5nm (4.4#-in). some are 4000rpm max, although 2-3000 is probably more likely as max at 60v rated speed on these small ones too. Some go to 90vdc but most seem 60vdc (90v is about a max for this small diam commutator).