K4 problems

[inkaneer]

Had problems with the tender of my K4 always derailing.  Determined that the problem was interference with the wiring between the tender and the locomotive.  I bought this locomotive on line at a well known hobby store/etailer but it was apparently a return because there were no instructions or parts list/diagram with it.

In any event in my attempt to 'fix' the problem the tender trucks which provide electrical pickup for the decoder were removed and later placed back.  What I don't know is if the trucks were replaced the same way or were replaced with the pickups reversed.  Does this make a difference or does the decoder sort that out?  The engine will not run now so I want to know if that is the problem or should I look for something else.

[richg]

If the loco came in a Bachmann box, it would have had a diagram sheet. Bachmann figures the buyer knows DCC. I have some Bachmann DCC steamers.
No loco manufacturer includes a manual about the loco/tender wiring that I am aware of. I usually see the wiring like this where someone has done the research.
I suspect you can search the Bachmann General and HO forums for tender wiring. There have been diagrams posted in the past.
The derailing issue is normally solved by adjusting the wires between the loco and tender. Some open the tender and add weight at the front.
Sounds like you did not draw a diagram of the tender wheels and wires when you disconnected. One truck picks up from one rail, the other truck, the opposite rail. I don't remember which right now. Others here will remember which. If one is not correct, when you plug in the loco, the DCC system sees a short.
Sometimes, a tender truck can swivel all the way around and create a short.
You said, does not run. No idea if you are seeing a short.
The decoder cannot "sort this out".

Try with one truck at a time connected.

Rich

[inkaneer]

reversed the wheelsets in the tender trucks and all works well now.  This engine seems to be very intolerant of track deficiencies.  In fact it is more intolerant than any of my N scale equipment.  It seems the slightest issue will cause it to derail.  I run it on the HO track included in my Liberty Belle On30 set.  There is a rail joiner missing between two pieces of curved track and the locomotive will derail everytime at that spot. 

[ebtnut]

If the rail joiner is missing, most likely the ends of the rails at the joint are out of line a bit.  Doesn't take much for a flange to pick the joint in such a case.  A check with an NMRA gauge would indicate whether the the track gauge was too narrow, exacerbating the situation.  The NMRA gauge will also let you check the wheel gauge to make sure they are up to standard as well.

[Doneldon]

inky-

Although it's a bad practice, you can sometimes get away with leaving a rail joiner off of a joint in straight track if things are otherwise
well aligned and tightly fastened to your roadbed. That is not true for joints on curves, however, for two reasons: First, rail ends without
joiners will tend to misalign themselves. Second, your train's wheels are already subject to lateral pressures on a curve. Combined, you
have a near fool-proof recipe for repeated derailments. Flawless trackwork is mandatory for reliable operations. Yes, wheels, trucks (I
make the distinction purposefully), weight and couplers also play a part but my observation is that track issues will always cause trouble,
even if everything else is up to spec. A few sloppy, unequalized trucks, wheels slightly out of gauge, somewhat light loads and barely
misaligned couplers will often scrape by but not track problems.

                                                                                                         -- D