Proper coupling is a major factor in stopping derailments at turnouts. Also you could remove the shell of the first car thats derailing, this way you can see much better whats going on under the car. Gently roll it back and forth through the turnout and observe whats happening.
I am learning model railroading as well, not quite as bad experience for me as what you are going through, but it takes patience, and perserverence.

That is one large ship, and a crew of only 13, amazing.

That was some great video, very interesting. I was surprised it took that much to derail the trains.

Our local PBS channel airs the program Tracks Ahead at 12:30 p.m. CST, today. Today's show is The Great Train Story, at Chicago Museum of Science. It should be interesting.
I thought I would post this in case anyone is interested.

Try it and see if it helps. Are the turnouts thrown into the correct position when backing into them? Try a few things, gently put weight on top of car without being hooked up to loco, push it through and see what happens. Make sure your track is laying flat and not binding. You will figure it out.
Does the very first one derail? Or do they derail after several cars have gone through it? Sometimes the turnouts have to be tweaked. You know a BFH and a crowbar. I had a LH turnout with derailments everytime, it was  straight from the box. I did some car tests without the body on the car, figured out where it was derailing, and why, tweaked it just a bit. It works beautiful, no derailment since, forward or backward, with different cars, and different locos.

I grew up in a railroad town, we hopped cars from one end of town to the other. Always chased by railroad dicks. Never had a train set, always wanted one. At 52 I bought my first one. I love it.

I think that is super. Good Job!

Thank you very much.

My wife and I spent part of our 28th wedding anniversary taking pictures. Here are a few from the rail yard in Superior, WI.

Yes thats it!  My wife is such a trooper, this is our 28 wedding anniversary and she is out with me taking pictures of rolling stock. That could be what it is used for.  I also took some pics of a SF loco, BNSF loco, from our rail yard in WI. I posted those on Sante Fe Bluffs favorite picture page.

The 3 minute mark on this video shows what they look like.
The video didnt work. I will going to town today, I will try and take a pic of the car.

I have seen these railcars in the local rail yard, and in some videos that I haven't been able to identify and would like to know what it is called and what it is used for. Description: Flat car, no sides, has a "truss like" structure running down the middle. From a side view looks almost like a Warren truss bridge sitting on a flat car. The view from the top would look like an "I" beam running down the middle of the flat car. I hope this description helps. I have just been referring to myself in my mind as a Truss car. What is it's correct name and what is it used for? Thanks.

Here is an interesting site to read: http://www.duluthport.com/pride/incan.html

I adjusted my coupler housings(sorry dont know the real term) on the loco and front of B Unit, moved them far to the right so when the loco makes the LH turn it pulls the B Unit trucks to the turn sooner. Its been working pretty good, I have made a dozen trips through the turnout, still had a derail a couple of times, but its better than it was. I guess basically what I did was shorten the distance between loco and B unit, all other cars follow fine. - rock

Gene, they are as delivered, so I will have to check the weight, also, I have been going through all the threads I can find, I may have to gauge the wheels? I will have to buy a gauge. I tried a heavy B Unit, its weighted like a loco but no motor, and it too derails following the loco. To me it seems like its hitting the frog head on, once in awhile, the B Unit (unweighted) will jump back on but all the wheels are not on the rail until it gets to the rerailer. I guess I have some troubleshooting ahead of me. Thank you for your help, any more suggestions, please let me know. - Rock     By the way, I too noticed the pivot pins are wobbly from loose rivets. I guess I will bring it back or send it in for a new one. I am thinking of picking up a #5 LH and see if thats any better. My treasurer will not be happy about that.