Those sound like tape drive motors. I think that because I have a
couple of similar 50-volt motors (also O1A but with 1/2" shafts) that
I was told were surplus from large tape drives. Dimensions of mine
are the same as yours (4 x 7) but the leads are 14 gage.

A quick resistance measurement of my motor suggests that stall
torque at 50 volts would be about 18 amps -- which isn't to say that
the motor would take that for any extended length of time without
overheating.

You seem to have a source of variable DC, so if you also have a way
of measuring motor temperature, you could test your motor by locking
the rotor and slowly raising voltage (and current) until the motor is
about 40 degrees C (72F) above ambient. Give it about 15 minutes
for it to reach equilibrium at each current setting and sneak up on
it. Most motors are rated at 40C rise so that should give you a good
estimate of the motor's current rating for continuous service. I'd
expect as first guess that these motors will probably handle about 9
amps without overheating but I'd start lower and sneak up on it.

Then you could clamp a lever arm to the shaft that bears on a scale
and measure stall torque at the rated current you've estimated.

Permanent magnet motors have a torque-speed curve that is quite
linear, so knowing no-load speed and full-load torque will pretty well
characterize the motor.

Feel free to email questions. I'm a retired electrical engineer,
enjoy playing with stuff like this. I claim no expertise on
available controllers, though. I've designed servomotor controllers
but I have no hands-dirty shop experience with available products as
the Gecko you or someone mentioned.

Regards

Don Foreman
Fridley, MN


On Sat, 15 Nov 2003 16:23:40 -0700, wrote:

Hi people,

At the local trash and treasure I spotted two 50v DC motors with 12g
red and black wires. Bought the pair for $8, so no great loss if they
are not useful. However, if I can find some more specs I am hoping
these, encodeers and some gecko drives will be the X-Y part of a
plasma cutter table.

No encoders, but they had a flat-belt pulley that drove a 3" diameter
x 3" long tachometer. I let the guy keep the tachs. g

All they have marked is...

OIA
135-0043-001
50vdc nominal

They have 5/8" diameter shaft, body about 4" diameter and 7" long.

At 50vdc they draw 0.4A free running at 1300rpm.

They only have two brushes but 90-deg apart.

Also the current stays at 0.4A from about 32v to 50v. Below 32v the
current slowly drops but not by much. Even at 20v it is still about
0.35A. Not sure if that helps or not.

Anyone have an idea of what where and who's??

Thanks in advance.