KLine engine jumps the track

I don't see it causing de-railing but the front roller is now too weak. That could cause it to act up crossing over switches. If that rear roller is now too stiff it could cause derailing. Did you bend it?

Rob

If I bent it I didn't mean to. Don't see how I could by just adding the board and switch, do you? Looks like you would have to pry it away from the chassis to bend it. Hmmmm.

Hmmmm;  Can you turn the body around and run other end forward? If so, I'd do that .

The traction tires trailing can be making the front of the truck lift and cause derailing. running other end forward eliminates that unless you are backing up, but then the coupler attached to the consist should help keep the truck down and lead it along the track.

Alternately, Add some weight over that front truck to force it flat on the rails.

Does that engine have two sets of motors? If so one set of motors may be going faster then the other set of motors, I had this happen with a K-Line MP-15 diesel.

Lee F.

Derailing on straight track is unusual. try running very slow and look close to see what is happening as the engine begins to lift off the rails. Try running in both directions. check the strength of the spring on the center rail roller, as the roller should spring back to be at same level as the outside wheels (without hitting the underframe first), resulting in the center roller applying a little pressure to the center rail for good electrical contact.

I have had various derailing issues with switches and s-curves, but never on a straight length of track

good luck: Joe K.

A pickup roller that does not have the proper tension can cause problems even on a straight run of of track.  I have seen this when the more expensive spring loaded pickup rollers get stuck in the "up" position.

Is the wiring to the power truck the same length as it was before your modification?  Is it possible that the wiring to the power truck is now too short?

Yes, I could turn the cab around 180 degrees but then the hand rails would not fit.

There is only one motor.

The front pickup roller is very weak and does not hang down as much as the rear roller. Should I replace the copper spring?

The wiring is no shorter than before. That was the first thing I thought of but binding isn't the problem.

I believe you will find due to the traction tires both mounted on the rear wheels of the power truck that the truck is doing a wheelie and lifting the front wheels enough to derail.  A fix is to place a spring over the tab on this truck where it enters the frame to push the front of this truck down from the frame.

"...place a spring over the tab on this truck ...."

Tab? Do you mean the rod in the center of the truck that is held to the chassis by a c-clip? Your idea makes sense because the front wheels do seem to lift off the track so maybe a coil spring would push the whole truck down. Great idea; I'll let you know if it works.

2:40pm  I just looked at it again and there's no room between the top of the truck and the chassis.

If you cannot add a spring, then check inside (under the plastic shell) to see if you can add some weight over the front wheels. this will help hold them down on the track.

Like a fishing weight? Looks like I need to go to a bait shop to fix my choo-choo.

If I am not mistaken onn top of the truck is a tab that has a 90 degree bend that fits in a slot in the frame  to limit how far the truck can turn.  The truck will need to be removed from the frame so you can disengage the tab and slide a spring over it before remounting the truck.

Yes, there is a "guide" that a spring could go around. I'll have to play with the tension until I get it right so that the spring won't effect the truck's ability to turn, right?

The spring just needs to add enough tension to overcome the wheelie and a dab of grease on the bottom of the frame where the spring rubs will allow it to turn easier.

Yeah, I agree. I'll look for my box of springs and try that tonight.

Forgot to mention a conical spring will work best with the big end toward the frame.

I may have to use whatever I can find but I have a small box of assorted springs that I bought at HD.

Here is a basic troubleshooting technique. If the loco did not derail before you added the circuit board, then the problem occurred during the addition.

Look at the wires you added, how the board is mounted, and if you removed the truck, whether the truck is reinstalled improperly.

You should not have to redesign the thing by adding weights and springs.

If it wasn't broke until you worked on it, and now it is broke, then you did something to it inadvertently while working on it. retrace your steps until you figure it out. 

The roller is out of place. It has a tab that fits into a slot in the spring. It's more likely that it is out of place than the spring being weak.