Traction motor will not rotate.

Drive motor and electrical issues

Traction motor will not rotate.

Postby Roger Wing » Thu Sep 11, 2014 4:59 pm

The drive motor on my E12s stopped.

The L relay pulls down and I get 36 volts to the motor armature but no rotation. An odd thing is that the voltmeter drops below zero to the peg when I move the control lever forward or reverse.

Do you have any ideas? I took the motor to a local shop and they said it was O.K. The field at the motor show 4.5 ohms. (Not connected to the motor.)
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Re: Traction motor will not rotate.

Postby FarmallMan » Thu Sep 11, 2014 7:00 pm

Check the condition of your fuse connections, and then remove the two screws from the top of the metal plate the fuse panel is mounted to and allow it to tip forward. Check the FR relay (which is on the right as viewed from the seat) for damage. Let us know what you find.

Nick 8-)
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Re: Traction motor will not rotate.

Postby pewamo758 » Sun Sep 14, 2014 1:15 am

Roger,

You might also check the edge connector on card one for bad a connection. Most likely though Nick is right. Welded contacts on the FR relay is quite common with the 12s.

Tom
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Re: Traction motor will not rotate.

Postby Roger Wing » Sun Sep 14, 2014 2:33 am

I have an E12s which has an excited field but uses relay 1A and 2A to take resistors out of series with the armature instead of field weakening. It appears to be a jump to the E15 from the 12s but has the motor of the 12s and relays "L", 1A, and 2A like the E15. The control fuse was O.K. And the relay on the right pulls down and is fine.

All relays pull down in sequence and when the motor is disconnected I have 34 volts on the field and the motor leads. But when I hook up the motor the relays sizzle and the motor does nothing. So I think the motor shop had better look at it again. What do you think?

I checked the field winding at 16 ohms and the armature showed .7 ohms. Don't you think it should be more than that. I quit looking at all else in wiring when I had 34 volts at the armature and field.

Thanks very much for your helpful quick response. I really appreciate your help. I 'll let you know what they say.
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Re: Traction motor will not rotate.

Postby Bushman » Sun Sep 14, 2014 5:12 am

Actually, the E12S is an E12 with the E15 motor.

Motor resistances sound fine. Just because the relay coils pull in doesn't mean they are making contact on all fingers. You will need to use a meter and check each finger contact to know for sure. The little pads burn up or blow off.

There are a few ways you can check the motor yourself, but I don't think that's the issue.
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Re: Traction motor will not rotate.

Postby FarmallMan » Sun Sep 14, 2014 12:27 pm

As Chad mentioned, with respect to the controls an E12S is in essence an E15 without field weakening. If you haven't already, I'd strongly advise you download a copy of the Homeowner's Service Manual: http://www.myelec-traks.com/OPS-74-4035.pdf It details the differences between the two models, and has all the appropriate troubleshooting diagrams and data.

Assuming it is functional, what does your "power use" meter indicate when the "fuel level" meter drops? Also, just a point of clarification (because it actually does matter) when you're measuring voltage, are you measuring across the two motor leads (or field leads), or from the motor leads to battery ground?

Check the motor armature and field for continuity to each other and for continuity to the case. Everything should be isolated. This is a good step to help rule out a bad motor.

Nick 8-)
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Re: Traction motor will not rotate.

Postby Roger Wing » Tue Sep 23, 2014 2:19 am

I confirmed the contacts on the rev relay are not welded and tested the field leads at the motor and they reverse polarity when the speed control is reversed. I test 34.5 volts at the disconnected armature leads at the motor. The motor and field and motor case are all isolated. I confirmed that applying 12 volts to the armature on the bench momentarily with a battery charger yields rotation. My conclusion is that since a meter shows 34.5 volts reliably at the armature leads, the only solution I can think of is a false reading that fails under a load on one of the contractors that is only allowing a tiny amperage to flow but yields a voltage reading. Tomorrow after work I am going to fabricate a #8 jumper and try shorting the l and 1a and 2a relays. It is such a simple path on this tractor I can' believe it's baffles me. I noticed though that CB-1 which is supposed to be a motor mounted thermal breaker is not on the motor at all. Any thoughts gentlemen? Oh and to answer your question, when the motor is hooked up and speed control in any actuated position the volt meter goes to the peg in the negative to the left and the ammeter showers only a slight twitch of movement maybe a 16th inch to the right.

Thank you very much for your help. I have an owners manual.
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Re: Traction motor will not rotate.

Postby Bushman » Tue Sep 23, 2014 2:37 am

Maybe check the resistor band. Sounds like there might be a slight connection, I agree.
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