Wire harness causing derail

[Capt Steve]

Hello all,

This is my first post on this board.  I am an aeromodeler for years and I am getting back into trains with my son.  I'm not shy to get "nutsy boltsy" with things, that's part of the fun.  At this point, we are starting out and want things to run right.

Question:  We just got a Spectrum 2-8-0.  The wheels take our 18" and 15" turns just fine.  However, the solid wires connecting the tender to the loco add force in the turns that causes the front wheels of the tender to derail. 

I have an idea on how to fix this, but I wanted to throw it out there to see what y'all active folks would do.  Any ideas???  Any tricks???

Thanks in advance,

Capt Steve

[Yampa Bob]

Hi Steve, welcome to the board.

We've all had this problem, and the fixes are fairly simple.

First, the tender needs weight added over the front wheels, about 1/2 ounce or so.

Second, move the wires around so they dont lift the tender wheels. I usually wrap excess wire around the drawbar before connecting it to the tender. Optionally you can pull the excess wire up inside the locomotive.

Third, adjust (bend) the drawbar so it pulls in the center of the tender post so it doesn't also lift the tender front.

Finally, mostly for convenience in keeping the drawbar attached, slip a short length (1/8") of  1/16" inside diameter silicone fuel tubing over the tender post. It will grip the post better if you first roughen the post a bit with a file, or cut a few threads with a 6-32 hex nut. Again make sure the drawbar is neither lifting the tender or pulling down on the silicone tubing.

In the following thread, I show where the weight can be added. (scroll down to the 6th post) For my Vandy tender, I added 3/4 ounce.

http://www.bachmanntrains.com/home-usa/board/index.php/topic,7439.0.html

If you have the USRA tender, the first picture shows the screw that secures the shell.  Don't remove any wheels, just swivel the front truck for access to the screw.  Wheelsets must be oriented as pictured or you will have a short.

Regards

[Capt Steve]

Wow, you guys are fast.  I knew there had to be a cure.

I will try that.  If for some straing reason I do not have success with that, let me ask you about my first thought...

I'm not a big fan of how stiff those wires are.  I can't help but think a more flexable wire (multi-strand) would have less force applied through it.  What about replacing them into a new wire harness that plugs into the tender?  Is that to drastic?  Can I find a new wire harness?  Black wire sure would look nicer than the multi color.

I'm just thinking before I do anything.
Capt Steve

[Yampa Bob]

Simple answer, don't change the wiring. The wires are already what I consider to be mimimum size for durability while handling and sufficient current flow. 

As for the wire colors, a black Sharpie permanent marker will easily take care of that.  

Regards

[Jim Banner]

If the decoder was factory installed, the wire lengths are probably near optimum, at least for the 18" radius curves.  Adding a little more weight to the front of the tender often helps.  Try a couple of 1/4 ounce weights, one on each side of the kingpin on which the front truck swivels.  These are best placed inside the tender, but in a pinch, you can put them under the tender floor.

If more weight does not help, then you may have to use a longer draw bar which you can make by drilling a couple of holes in a suitable piece of brass or even plastic.  As a first try, put the holes about 1/8" farther apart than the present ones.

Derails from draw bar problems often occur as the locomotive and tender go into a tight curve.  The rear overhang of the locomotive swings way outside the centerline of the track while the coupling pin at the front of the tender is still centered.   This sideways displacement tends to pull the front tender wheels sideways off the track.  The longer draw bar reduces the sideways pull on the front of the tender.  In extreme cases it may be necessary to move the locomotive coupling pin closer toward the rear drivers and use a much longer draw bar.  The down side of this is that the draw bar can then swing sideways far enough to catch on piping, steps, etc. on the locomotive and tip the locomotive off the rails, particularly when backing up.

Ultimately, draw bar problems arise when we try to run our equipment around curves which are too tight for them.  Spiral easements going into such curves help, but they often take up the space we are trying to save by using tight curves.  However, a compromise that sometimes works is to use a larger radius for the first section of track going into a curve.  For example, the following sequence of tracks:
[straight] [18 R. curve] [15 R. curve] ... [15 R. curve] [ 18 R. curve] [straight]
Having an 18" Radius curve at each end helps ease the locomotive and tender into the curve no matter which direction you are running.

I see both you and Yampa Bob have posted since I started typing but will post the above anyway

If the decoder was factory installed, I would try the alternative solutions before changing the wiring.  If you installed the decoder yourself, you could try substituting lighter wire.  If you have an old computer mouse around, strip the individual wires out of its cable and use them.  When installing decoders, it helps if you make the holes in the back of the locomotive and the front of the tender oversize so that the wires can bend a little inside the tender as well as outside.  Oversize holes will also let the wires slide in and out by themselves as needed.  If Bob's suggestion of wrapping the wires around the drawbar doesn't work for you, try bending them into a hair pin shape vertically between locomotive and tender.  This doesn't look as nice but it minimizes the forces the wires can apply to the tender.  By all means paint the wires black.  But try to keep the ends their proper colours.  These colours all have meaning and make trouble shooting much, much easier. 

[Capt Steve]

Thank you, Gentlemen.

I was thinking replacing the wires was a bit much.

We definately have track issues.  We are trying to get a layout that works well, before we move onto the next step.  Function first.

I knew this would be the place to get some great knowledge. 

Capt Steve

[Yampa Bob]

Steve,
Something else I forgot in my first post. The drawbar hole that slips over the tender post is usually rough with sharp edges. To keep it from binding or cutting into the post, I slightly ream, round and smooth the hole edges.