MTH Railking Challenger Motors not running in sync

Have you checked the wire plug-ins for the motors? There is the possibility that the circuit board can be bad.

I had a K-Line MP-15 with a bad circuit board and it did something similar, K-Line fixed it but I had to mail it in.

Lee Fritz

onthelam posted:

I have a Railking Challenger that was upgraded to PS 2.0 a couple of years ago. Lately I noticed that the two motors are not running in sync. The traction tires are good and the motors are secured. Anything else I should be checking?

Tom

I'm not really  sure what you mean? Is one motor trying to run in the opposite direction, or not turning at all.  Both motors go the same plug in on the circuit board.  The articulated engine's drivers are not always in sync with each set.  need  a little more info??

Yes, I'm curious, too - but I'm not sure what you mean. Noticeably different speeds?

It appears that the rear drive wheels are moving slower than the front drive wheels causing the front drive wheels to spin going up a 2% grade. I thought I threw a traction tire but all the tires are good. the engine also seems to jerk while moving.

It is not the circuit board.  The wires coming from the 5 pin are from the same source on the board.  It may be possible the rear motor is going bad.   Would be nice if you remove shell and tell which one has the tach reader.  But what happens is the tach reader motor sets the feedback to determine speed.  Both motors get the same voltage, which should maintain speed.  If one motor can start slipping wheel with that voltage, the other motor is not turning as fast with the given voltage.   I would inspect the rear motor for binding, and winding damage.  Motor do occasionally fail.   G

Another possibility is that the weight distribution isn't even and the wheels with less weight can spin.  Like George says, only one has the tach and determines the power to the motors.  Even slightly uneven track or the start of a grade can cause the issue.

I have that loco.  Under certain track configurations and heavy load at the top of a grade, one set of drivers will spin and the other doesn't, so loco stalls.  I have a GG-1 that's worse.

I suspect the set that is spinning is the ones with the tach.  Since it takes very little power to spin them, the total power falls off to the motors, the one that still has traction doesn't have enough power to move things.

Guys,

Thanks for the input, it will be my weekend project.

Tom

Tom, if your examination per GGG's post above turns up nothing, I doubt there is anything can be done.  The cause would be as GRJ suggests, and short of somehow mechanically connecting the motors, I can't think of a cure..

In the G scale Challenger, a spring should be added to the front engine's mount to apply some load onto it. As stock, it will spin every chance it gets. That causes the engine to loose it's tractive effort!!  ( Yeah, like I know what I'm talkin' about there....). They never really truly are in perfect sync. They're independent of each other physically. They get their power from the same source.

I do not own an O scale version to compare. I would imagine that there's a tach unit on one motor only. It's the rear one in G scale though. This subject pops up time and again about the way the motors work. When a motor is on the way out, all bets are off. I have not lost any motors myself, in over ten years. I don't overtax my engines asking them to pull the house around though.

Usually something's stuck in there like a traction tire or grit.