New MTH Diesel lurching

[ericstrains]

Hey guys,

I just got a new MTH ES44 diesel today, but unfortunately it lurches when it runs and this is especially noticeable at low speeds (3-10 smph). I examined all the gears and so forth and haven't found any probable cause. From my observations, it seems that the rear motor is the culprit, but I'm not sure. I'm probably just going to send it back to MTH for repair, but I was curious if anyone knows what could cause this? Does it sound like a mechanical problem or a problem with the digital system?

It's a pretty subtle lurching action that happens in both forward and reverse. I'm a big fan of running trains at low speeds, so I was pretty bummed to have a new engine do this out of the box. :(

Anyway, your thoughts are welcome.

Thanks,
Eric

[tbrook]

To see what is causing the problem you would need to dissemble the engine. Remove both motors from the wheel gears so the motors can run freely. Then, turn on the power to the engine and watch the motors turn. If it is a motor problem I suspect that one motor is not starting up at the same low voltage as the other motor therefore causing the engine to 'lurch.' I would also turn the drive wheels with my hand, now that the motors are out, to make sure each set of wheels moves free. You can also reinstall one motor at a time to see which motor does not run smooth when it has a load on it.

My best advice is to send it back as it is a brand new engine.

A 'can' motor at a very slow speeds does 'jerk.' Try taking a uninstalled 'can' motor and turn the armature by hand and you will feel the jerking effect. This effect is caused by the 'can' armature passing through the permanent magnetic field. To mask this effect the motor needs to have drive gearing to allow the motor to run faster while the gears allow the engine's drive wheels to move slower.

Hope this helps,
Ted