One problem with trying to straighten an old car body by tightening the truss rods is that the wood in the sills is very tired where the ends of the truss rods are attached. It has been subjected to localized stress over the years. Typically you will find lots of cracks and possibly dry rot in the cracks. If you apply additional force trying to staighten the car body, you stand the danger of pulling the truss rod end through the wood. If the end of the truss rod is attached to a metal casting, it may be pulled out of the wood with damage to the sill. Applying lots of epoxy glue or Git Rot to the sill in the vicinity of truss rod attachment might be a good idea.

That's why the best approach is to level the car with jacks under the king posts then tighten the truss rods. After the truss rods have reached normal tension, lower the jacks very slowly and hope that things don't pull apart.

fkrock:

Good caution. That's why set-up needs to happen at the time of a structural rebuild.

Would it be possible to explain what you mean by "set-up"? Perhaps we use a different set of words to mean the same thing but your explanation might add to our knowledge base.

In the near future, we will begin rehabilitation of a wood car with truss rods. Although rebuilt in 1945 due to a fire it is still 60+ years old and we are concerned. Thus, any information we can get will help our effort.

Thank You
Robert

Robert:

Sure, by "set-up" I mean the sequence given in my 1214 21 February 2011 post. In short, the initial tightening should not be attempted short of a complete structural frame blueprint/rebuild by which one knows what one is tightening. The actual tightening of the truss rods, setting the frame camber, is the last step.

Steve

Thank you. This thread is great!

Robert
FVHRS

I will question whether a full rebuild is required... I have straightened a couple of cars successfully, by first inspecting for structural issues, repairing any found, then tightening various rods... in most cases a bit at a time, in one case over a period of a year, through northern California wet and dry seasons. I do tend to jack platforms level rather than using the rods to lift them...

I have replaced some structural members, including splicing a side sill, and consolidating an end beam with epoxy, but only as needed, and depend mostly on old wood. Yes, I have seen wood that has failed separately from termites or dry rot, particularly when fir or pine was used on end beams in place of oak or good Douglas fir.

I had a recent experience with a car where I pulled a 2" sag out of the corner simply by tightening the wall truss, truss rod. I did spend close to 8 hours inspecting the car before tightening the first rod. That car was generally loose everywhere... simply tightening the car fixed it...

I continue to look for 19th century information on how to adjust a railroad car. By the way, I have found that MCB allows 1 hour to tighten the rods on a freight car if empty, but 1.75 hours if loaded... supporting BAERM's information.

The only thing that worries me about 19th century instructions is they apply to 19th century cars in the 19th... not the 21st. I expect their instructions would be quite different for a 100++ year old car.

They would probably say "replace wood", but not appreciative of the fact that if they knew of our world - 100 years of rot and you can't buy old-growth anymore, just these "pecker poles" as they call em in the wood biz.

Nobody railroading in the 19th century would have any expectation that the wooden cars they worked on every day would last 20 years, much less over a century. I'm happy we are now making replicas to use - either intentionally, or through replacement of what was original with new material to the extent that most of the original stuff is gone by default.

dave

Dave:

Correct. I usually tell folks that our Laconia and Pullman day coaches were built as ten-year throw aways. That they still roll is remarkable.

Randy:

A complete rebuild is not required, as I mentioned as an alternative, if one has blue-printed the frame and is comfortable with the scantling sizes, engineering, etc. The main point is that some kind of analysis has to be performed prior to cranking away on the turnbuckles.

I have several thoughts...

If we don't occasionally adjust the various rods, we are not maintaining the cars... Wood grows and shrinks with changes in moisture.

There are cars that need rods adjusted, but don't need to be rebuilt. I think we are collectively bright enough to tell which cars can be adjusted.

If we can't address these basic maintenance issues, then we shouldn't be using wooden cars. (which is a legitimate debate... wood cars suffer more when used than steel)

This is not the grab a park engine and build a fire...

Randy

Agreed, sir. That's a fine statement of truss rod practice.