Pilot truck shorts out and sparks

First, observation of the train.

Have the axle bearings in the leading truck worn to allow the axle to touch the center rail?

Truck mounting screw in too far and touching a smoke or headlight wire?

Any sideplate wear to permit the axle to move vertically?

Has the drawbar worn through the tether?

Check the collectors for wear. (roller pick-ups)

Have any of the headlight wires in the boiler come loose? Open front and check.

email Marty Fitzhenry

can you post up a picture of the underside of the lead truck?....you mentioned that its off right now........if you can, give close ups where the arc is occurring. You should be able to see where an arc occurred.....If the tension spring is all mashed down, most likely is allowing the pin to drop down far enough to touch the center rail. This will be the case especially on uneven track.....There are quite a few really good Techs on this forum, I'm sure someone will give you a fix......

I placed the pilot truck on the track and the sparking happened just like when the pilot truck was attached to the engine. Upon closer observation, I could see that it was the old spring in the center of the truck that was the culprit. I, (temporarily), wound electrical tape around the post where the spring should be. This worked. The engine ran through all tests, forward, backward, all sounds, lights, etc., complete circles, (82 rad.), all functions work great. I was also able to change the traction tire and oil and grease the engine while working on the truck. Thank you all for your concern and great answers to my question.

I am having a very similar sparking problem and I’d like a clarification on what “spring” you are talking about. The truck pivots on a flange of the motor bracket. That’s where I see my sparks. Where is this spring ?

I had a similar problem with my MTH Dreyfuss Hudson. The screw that holds the pilot truck to the loco frame was just barely grazing the center rail, enough to spark and blow a fuse. This was how it came from the factory and it had never been taken apart, and everything looked normal to me. I put a small piece of electrical tape over the screw head, and problem solved. 

Gary Liebisch posted:

I am having a very similar sparking problem and I’d like a clarification on what “spring” you are talking about. The truck pivots on a flange of the motor bracket. That’s where I see my sparks. Where is this spring ?

Most pilot trucks have a spring somewhere that pushes the truck down. This pressure keeps the light truck railed better than gravity alone. (is this the EXACT same engine?)

  This spring appears to surround a long rivet's shaft(?) The rivet floats vs being held fast, the spring holds it up. A bad spring cant even hold the rivet up so it drops slightly, hitting the rail.

 Your sparks sound like they are up high at a connection point.  If it doesn't bother performance, I would suspect your sparks are minor, like that of a small carpet static spark. That could be the normal electrical flow of ground/common to the frame when the rubber tired drivers loose flange contact, or the trailing truck looses contact etc., forcing a bit more electricity to be drawn from the pilot truck.  Dirty wheels or track could cause this too.

If that is the case; motor might have a slight bit of trouble pulling a good common/ground.   You could tether an additional ground from the tender wheels/chassis to the engine chassis.

  Also, pressure has a huge effect on electric connections. The more the better. So a spring at any connection, applying pressure to the connection, helps delivery of power.  A weak trailing truck connection would cause a heavier draw thru the P-truck too, etc etc etc.

  Without a photo or drawing, only folks with the loco or tons and tons of repair experience know for sure. Not that many many others aren't capable, but it is real time consuming haphazard guess work. A great repair tech may have never seen one before either, let alone worked on one.

     Don't folks have cameras anymore? Repair threads seem notably void of photos lately in comarison to past years imo. I know some techs are plain tired of having to ask for numbers, photos, etc, and skip right over some posts, fyi y'all.

The spring is in the center of the pilot truck. The engine is around 17 years old, so the spring just got old and weak. That's when the sparking went wild. I purchased a box of spring assortments at a local hardware store. I was able to find a good match for the old spring and the engine runs great now. The pilot truck requires the tension, that the new spring offered, to keep the truck from jumping the track on tighter curves and tight switches. Although on very large radius curves, (82 radius in my case), it did not seem to matter as much when I only used an electrical tape temporary substitution before I added the new spring. I'm sorry that I did not take photos of the replacement process. I guess I didn't have much confidence in my mechanical abilities. I'm checking all my older engines for spring tension, while I'm in the process of changing tires, oiling, etc. I will take photos in the future, should they be at all interesting? I hope that this helps a bit. As always, this is a terrific forum, loaded with expert advice. Much thanks to all...