I was recently doing a preservation study for a wooden railroad car… and a question came up… I can’t find a 19th century reference about how to tighten truss or other tension rods on a car… In the case of this car, after inspecting the frame, and finding the wood generally sound, I worked with the group to tighten the under body truss rods, the platform truss rods, and the wall system truss rods, and in the process pulled a 2” sag out of one corner, and straightened the platforms.

During various restorations, I have learned to tighten truss rods, brace rods, platform tension and truss rods and body truss rods and braces to harden up and even straighten a car (or three… ) but so far have found few 19th century references…

William Voss' Railway Car Construction (1892 for National Car Builder, since reprinted, most recently by Orange Empire Railway Museum ) "Quite a number of our prominent builders are now using a turn buckle in their truss-rods, but it is not necessary to go to this additional expense, as the rods can as well be screwed up by the nuts on the end." (Voss is discussing truss rods running from end beam to end beam, as more commonly found in freight cars, not those anchored at the bolster as on many passenger cars.)

A second source… the Master Car Builders’ Association Code of Rules for Interchange of Traffic (revised 1912) includes allowable charges for (all examples for freight cars) “Body Truss Rod, tightening and replacing on saddle, ½ hr., charge .12” (p68) and “Trussing Car, Empty 1hr, charge .24, Trussing car, loaded, 1 ¾ hr., charge .42” (p78) Elsewhere it is noted that you cannot bill for less than .25, but can accumulate various charges to exceed .25, so logically if a car was loose and your car tonk chose to tighten it, it might be so minor that it isn’t chargeable.

Either this was so obvious that it wasn’t discussed, or the cars didn’t live long enough to need them tightened, or the men who tightened the rods (I assume the car tonks) were not literate (as in not reading about work, not, not able to read)
I check the truss rods on our wooden flatcars annually, and tighten them for the first 3 years after rebuilding, then every

Any thoughts… and particularly any references

makes me think of some screen doors using truss rods, various other mechanical devices using truss screws for adjustment, I wonder if some small bridges made use of truss adjustments.

I have handbuilt some HO wood cars detailed with truss, its probably important in keeping the car straight and level for best riding ability, a sag or warp showing in the wood immediatly shows failures in the wood. As running goes this stresses the wood so adjustments over time would be done. I wouldnt be surprised if the train conductor inspecting the train would check brakes and also carry a truss bar adjuster for a quickie tweak. I didnt know you would also adjust at the wire ends, which is true to not use the reverse screw adjuster in the middle. It may depend on the specific car's needs for adjusting enroute. Do note early streetcars-interurbans were wood construction with same adjusters.

Over time I would think stress would burn into wood and need replacement from time to time, any current wood equipment in restoration may prefer to look into steel frame assist support, or have a designed frame replacement policy.

The group I was assisting discussed a steel sub frame, but as a preservation group, is staying with wood.

How you maintain equipment has a lot to do with your mission... are you preserving cars... then stay with how they were built... are you running a train ride, if so, consider betterments...

We have a 1882 wooden narrow gauge car at our site... it had a 2"+ sag at one corner... we had to splice the (original) side sill (following MCB recommendations) then re-tensioned the car over a year, with no sag...

Wood was an cost effective appropriate technology... before 1900 or so... and is still appropriate technology in a museum preserving 19th century technology.

The group has two other cars with failed side sills... and intact center and intermediate sills.... a steel sub-frame would replace the still good center sills, and still require new wood side sills...

Sometimes we over think betterments...

Back to the original question... what do we know about tightening rods in wooden railroad cars?

This is what I recall hearing about tightening truss rods, etc.

1. work on a firm level surface (reason coming up)
2. release tension
3. jack and block the car into a level alignment (this is the reason for a firm surface) Use carpenters' level, string line, or even contractors' survey-type level. This will get everything (like joints) back into position
4. tighten the truss rods

I am not sure where I heard this.

Our's is a variation of Mr. Norden's as part of a comprehensive car structure rebuild:
- Level carbody;
- Free up the mechanism of the turnbuckles (no mean feat after 100 years);
- Perform structural rebuild, if needed with regard to truss rod function;
- Recheck level;
- Tighten trussrods incrementally and in turn in order to achieve minimal camber for lading/preload.

When finished out and loaded, we like our cars to have the slightest camber in order to prevent hogging or sag in the future. The camber/lading is evaluated on a periodic basis to see how the car is bearing up.

About 12 or so years ago, I helped straighten the Mammoth Cave Railroad wood combine, which was undergoing a cosmetic restoration for the National Park Service at the Kentucky Railway Museum. Structurally, the car was in very good shape with having been under cover most of it's time in preservation, since the late 1930s, though the car was very saggy and looked like it had been "twisted." After ensuring the car was in solid structural condition, we cleaned up the exposed threads on the truss rods, and for a couple of weeks doused the turnbuckle with a penetrating oil. After a few weeks of this, we pretty much followed the instructions posted above.

I think we used a switch iron to manipulate the turnbuckles, and moved very slowly. Checking a few measurements after every quarter turn or so. After about a half day's work, we had the car straightened. It still loooks pretty straight today.

This actually begs a question that one of our friends at Strasburg could answer. I know they do very comprehensive structrual rebuilds of their in-service cars. After rebuild, are the truss rods still operational, or are they merely there for looks?

This isn't just for wood cars. When I was a equipment specialist (read junior, junior project engineer) on a new passenger car build in the '90's, the new cars we were building at the time were built with 5/8-3/4" camber.

About five years ago I was staff engineer at a company which had a government grant to build a "roll over rig"; a retired NJT "Comet" car that could be placed at any position from plumb to 180 degrees for the training of emergency responders (black-out car, fill with smoke, tilt 45 degrees, remove occupants). Three "hoops" were constructed, and three concrete and roller fixtures were laid to accomodate the pivoting via a capstan winch. Two newly college minted ME's worked out the hoops in CAD, with very precise measurements to clamp to the carbody, and in passing I asked:

"What did you do about the camber?"
"What camber?"
"The center of the car is 1" higher than the ends."
"Really. Won't the car flex?"
"No."

Upon laser transiting, it was found that the camber of a 35 year old Comet car was still 1 1/8" at the center. Thankfully, the young engineers moved the Comet car "hole" for the center hoop 1 1/8" off center before ordering or cutting any metal.





Steve

Very much operational, sir.

Steve, thanks! How often are they checked or adjusted on average?

Dave:

Adjustment is as needed - that is, rarely. They get checked on a regular, perdiodic basis, along with other frame and carbody components.

The Northwestern Pacific Railroad Historical Society is restoring two wooden passenger cars that lost their underbody truss rods. The 45-foot long coach had an inverted truss rod (in the wall) cut out at two locations. The 50-foot-long baggage car had several of the inverted truss rods cut.

The 1879 Car Builders Dictionary made no mention of the amount of camber needed. The 1888, 1895 and 1909 CBD's stated that freight cars were heavily cambered when new by tightening the truss rods, but passenger cars had little or no camber. "Heavily" and "little" were not defined. In his book on American passenger cars John H. White Jr., says many wooden passenger cars were built with cambers of as much as 1 1/2 inches.

My question to the group is, should a camber of 1 1/2 inch (or more, or less) be set into these cars when the welding commences?


Mike Manson

Camber is a flat car is needed... but I question how much camber a passenger car needs. Our narrow gauge flatcars weigh about 6 tons, including trucks (roughly a ton a piece), and were designed to be loaded with 15 tons for a total of 21 tons or so... Taking the trucks into account a three times load to tare...

A passenger car, (I continue to speak 19th century narrow gauge) might weigh 11 or 12 tons, again, two or three tons for the trucks... and be loaded with only 4.5 tons of passengers... using modern people, not skinny 19th century people) a ratio of tare to load of only .25...

19th century passenger cars commonly had the siding glued and nailed to the body... suggesting very little flex, which would at least break the paint film between the siding... and be very noticeable...

I understand that some cars had camber to make the cars look straight... without it they look like they have sagged.

I continue to hope to find inspection instructions or some similar document, telling how to inspect and adjust truss rods...

In the mean time inspect cars for structural stability, then I adjust rods... cars magically get straight... All is good...

I would.

.

As mere hearsay, I'm taken to understand that WRM has had difficulty tightening truss rods while the car is "on the hoof", and they prefer to jack the car to the desired level, so there is less/no load on the trusses, then tighten.