Bachmann Union Pacific 866 Engine Not Working

[jward]

The old pancake motor. I usually try to avoid those, because the newer locomotives are so much better.

First, that 18v reading you were getting, is it AC or DC? It should be DC and lower than 18 volts. 18v sounds like typical AC voltage. Can you vary the voltage by turning the speed control knob? Can you reverse the polarity by moving the knob left or right of center? If you answered yes to these questions your controller is good.

The motor is geared directly to the wheels through spur gears. There is no worm so you should be able to turn the wheels by hand. If you can do that, the motor is not seized.

You should have a set of test leads, the kind with alligator clips on the end. With those, you can clip one end to the rails, and the and the other to the contacts on the motor. If it runs then the motor is good and your problem is in the wiring.

[MOP]

There are two distinct ports, AC and DC. I have it connected to DC and it reads 18 volts. Yes, the voltage varies and changes polarity. Do you think the high voltage may have caused the motor to burn?

I am unable to move the wheels manually. Should they move? If the motor is jammed then what can I do about it, anything or is it irreparable?

I will try to get the testing wires with alligator clips and see how that goes.

[trainman203]

If it was me I'd give up, punt, snd buy a new engine. 

[jward]

There are two distinct ports, AC and DC. I have it connected to DC and it reads 18 volts. Yes, the voltage varies and changes polarity. Do you think the high voltage may have caused the motor to burn?

I am unable to move the wheels manually. Should they move? If the motor is jammed then what can I do about it, anything or is it irreparable?
 

The voltage should be fine. VOltage readings can be affected by the internal circuitry of the power supply. It does seem a little high but without a load like a locomotive it's not going to read exactly 12 volts. I won't go into electronic theory here other than to say that voltage across any given point in a circuit is related to the resistance across that point as compared to the rest of the circuit. If you are reading between the rails with nothing on the track the meter sees it as an open circuit (infinite resistance) and will read the entire voltage output of the power supply. Add the locomotive to the track and even if it's not moving it is no longer an open circuit and the voltage reading drops accordingly.

As for the pancake motor, my experience with these are that yes, you should be able to turn the wheels by hand, but they won't free roll. There will be quite a bit of resistance. That you're not able to do that points to either motor damage or a gear bind. SOmetomes, grit gets in the fears that can prevent the wheels from turning. Usually in that case, they won't turn one direction, but you can roll them back the other direction until the gears bind again. If that is the case, I'd completely disassemble the gears, looking at each one carefully under a magnifier for anything in the gear teeth. If you find anything, remove it. DO this for each gear, and put it back together.

The motor itself in Bachmann locomotives of that era was very cheaply made, with plastic bearings that would overheat when the motor got hot. If there was enough heat to soften the plastic, the motor would seize. As a teenager, I worked for a display railroad where we ran alot of Bachmann locomotives. Under heavy usage we ran into seized motors quite often, and the owner had a supply of power trucks which we swapped out as needed. Even then, with parts readily available for these locomotives, there was no way I knew of to fix a seized motor. If there was, we'd have worked on them during the slow periods when we had no visitors and the railroad was shut down.

As trainman has said, in the long run you'd probably be better off with a newer locomotive. Bachmann has refined these old train set GP40s into a nice running, decent quality locomotive and I have at least a dozen of them. The pancake motor is long gone, and I haven't seen them listed in the Bachmann parts store for several years. If you do have a seized motor, you might be able to find a similar locomotive for cheap at a train show that is in working order and use it as a parts source to repair the locomotive you have. But you will still be dealing with the same drawbacks of the original locomotive.

[MOP]

If it was me I'd give up, punt, snd buy a new engine. 

You are right. That's probably the right thing to do. I have some free time so just trying to figure it out.

[MOP]

@jward. Thank you for the detailed and informative reply. So here is something interesting. I took a 9V battery and touched it to the two metal terminals on the motor and it came to life. The lights came on and the wheels started moving. So what do we make of that? Why would the motor not work on the track but will work with a 9V battery?

[trainman203]

Because the track is the problem. Not the engine.  Did you ever try this engine on another layout?

You need to check each and every rail joiner and wiring connection.

[MOP]

Because the track is the problem. Not the engine.  Did you ever try this engine on another layout?

You need to check each and every rail joiner and wiring connection.

We took it to a model train shop and they were kind enough to test it on their track and it didn't work.

The track has current when I test it with a multimeter. I have cleaned the track and wheels with EZ lubricant.

[trainman203]

If the motor runs when a battery is touched to the engine connections, power is in the track, but the engine doesn't run, then you have to assume that some connectivity problem is between the trucks and the motor.  Contact wipers not touching the wheels, some wire loose inside somewhere, I don't know ..... I don't have any diesels to base experience on.  But with all the givens you've told us, the problem has to be between the trucks and the motor.

[MOP]

Yes, it seems that way that the problem is somewhere between the truck and the motor. I wonder if the loose wire on the back truck has any role in this situation. Overall, with my limited experience I am hesitant to open the engine motor but I may just have to.

[trainman203]

If one truck picks up power from one rail and the other truck picks up from the other rail, then that is certainly the issue. You will probably have to re-solder it to some metal tab somewhere.

[MOP]

Yes, that could be the case. I have tried to find some type of wire drawing but so far no luck.

[trainman203]

I don't know that model at all, but I bet if you take the shell off, somewhere you're going to see some kind of unassigned electrical contact with solder on it and nothing being held onto it by the solder.

Didn't you take that thing to a train store? Don't they have a repair guy there?

[jward]

@jward. Thank you for the detailed and informative reply. So here is something interesting. I took a 9V battery and touched it to the two metal terminals on the motor and it came to life. The lights came on and the wheels started moving. So what do we make of that? Why would the motor not work on the track but will work with a 9V battery?

Ao far you've tested the motor. It works.

You've tested the controller. It also works.

Have you measures the voltage betwen the two rails? with no locomotive on the track it should read similar to the controller. If this also works, then.....

You mentioned that there was a wire loose on the locomotive. I suspect this is the cause of your problems, but we need to find out where it goes. With the locomotive on the track and the power turned on, touch the wire to a metal wheel on either one side of the locomotive or the other. If the disconnected wire is the problem, tapping one of the wheels should get it to move. Make a note of which side the wheel is on, because that is the side the wire needs to be connected to.

[MOP]

It turns out that the loose wire is the issue because when I directly connect the wires to the track the engine starts working. Thank you for the advice, it worked.

The problem now left is that apparently a different type of mechanism was used to connect these wires to the wheels than the usual soldering. I may have to post some pictures because it's hard to explain. I have an idea as to what needs to be done but with limited experience and tight space have not had much success so far.

The store we took the train to was able to test it but they don't fix trains.