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View Full Version : Help with DC gear head motors

StephenK
12-05-2005, 06:20 PM
I was given two Bodine DC gear motors which look to be in good shape. Hopefully I would like to find out if they really do run. The information on the name plates under volts is as follows:

Motor 1. 142A-98FDC Amp 1.1
Motor 2. 105A -86FDC

There are four leads coming out of each motor. Two are blue and two are black.

With such little information, can anyone shed some light on these motors. Neither Bodine who told me that they were opsolete or another DC motor co. who didn,t know, were of any help.

darryl
12-06-2005, 12:52 AM
Can't help specifically, but since no-one else has piped in, I'll throw in a few cents worth.
The sparse info seems to suggest a field winding, and not a permanent magnet field. If this is true, then two wires are for the field winding, and the other two are for the armature. It would seem that motor 1 wants 142 volts fed to the armature, and 98 volts fed to the field winding. The 1.1 amp rating could be the combined current draw, probably that's what it is. I would expect the field to draw about 1/4 to 1/3 of the current. One way to guess a little closer is to measure the resistance of the windings. Two blues is probably one winding, and two blacks probably the other. If either pair shows a dead short, it could be for a built-in thermal breaker, leaving the other two wires to feed both armature and field at the same time, as in series connected internally. Measure across two blacks, then across the blues, then from one black to one blue. I think you'll find a resistance across the black wires, same for the blue, but no connection between black and blue.
Knowing the resistances, you (or I) could do some math and determine whether it would be safe to put 100 volts or so DC on a pair of wires.
This brings up a nasty potential problem. Where do you get 100 or 140 odd volts DC? If these motors are properly functional, and I suspect they may well be, you'll need to supply the juice in proper form. You'll need a 'power supply' to run them.
Enough said for now.

sch
12-06-2005, 11:39 AM
Nice thing about DC motors is they run on most any voltage below what they are rated at. After going over the motors with an ohm meter as per Darryl's post you could hook them up to a battery charger and observe the action. If the gear redux is high and the volts a lot lower than usual then the motor will run very slowly so it may take a bit of study to see what is going on. The current draw meter on the charger will clue you in to a problem also. If no difficulties here then a variac and a 400VDC 10-20amp bridge (\$5 or so)will allow you to ramp up the voltage in a controlled fashion and a series ammeter allow monitering the current draw.
Steve