Brought to you by the same man who built the Leviathan: http://www.youtube.com/watch?v=7jf6FNnQxmc&feature=youtu.be

Why does that car have two four wheel trucks as opposed to say two six wheel trucks, or even two four wheel trucks? Is each of all four of those trucks connected to the car frame with its own center bearing; or is there some type of span bolster used to combine each pair of trucks before connecting to the car frame?

It looks like each truck attaches to the car frame. It seems like that would create some difficulty in negotiating curves. I don't recall ever seeing a truck arrangement like that, if the trucks are not using span bolsters.

The car being copied had been built during the Civil War with four 4-wheel trucks.

Some images can found on line:
Lincoln's Private Rail Car
President Abraham Lincoln's railroad funeral car

Here is one showing the car later after being used as a coach on the Colorado Central.

Brian,

Thanks for those links. I realize that the car was built with the double trucks, so I am questioning that original design, not the plan for the replication. I would assume that the double truck design was highly experimental at the time it was built. From your link, I see that two of the trucks were removed for later service on the Colorado Central.

I wonder if the replication effort has the detail plans for the original mechanical details of the double truck arrangement. I wonder if perhaps either the inner or outer trucks were attached to the car fame with their center bearings in a connection with the car that would allow the trucks to slide side to side (relative to the car) as the car passed through curves.

I saw some of the research material a dozen or so years ago when Dr. Wesolowski built the 1" scale model that is now on display at the Lincoln museum in Springfield. As I recall, the car has span bolsters, but each truck has its own side bearings to support the car body. I think the idea was to provide a better ride. Railroads were pretty new technology at the time, and they were still discovering all the things that didn't work as well as envisioned. This was one of them, I'm sure.

Even more interesting was the car was built with "compromise" wheels, with the back-to-back set for standard gauge track but having steps in the tread that would hopefully keep the wheel centered in 5' gauge. Bet they don't replicate that feature. If the car ever derailed, with all those wheels it would be all over the landscape.

Pullman constructed a few of his Palace Hotel Cars in the late 1860s that also used this 4 truck arrangement, but soon dropped it. It has been noted that when the Lincoln car was sold to the Union Pacific for use as a directors car, the combination of this wheel arrangement and the compromise wheel treads led to complaints of a notoriously rough ride.

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I did not realize that those trucks had compromise wheels. I wonder if that is part of the reason for adding two extra trucks. Typically the reason for using extra trucks would be to support extra weight as is the case with four-truck flatcars. I assume that the Lincoln car does not have extra weight that required the addition of two extra trucks. So the only reason I can think of for the extra trucks was to make the car ride better. But I cannot imagine exactly how that would come about. That would be a very interesting engineering proposition.

There are some good side elevation photo views in the Youtube video, and they appear to show a solid mass between the top of each truck and the underframe of the car. To my eye, the view does not support the existence of a span bolster, but rather, direct connection of each truck to the car frame. But how could that negotiate a curve? Even though each truck could pivot, their four pivot points would always fall in a straight line.

The compromise wheels could compensate for a curve to some extent, but only when running on the widest of the two gages.

I'm going to make a little jog off topic for a moment. A couple decades ago, the Newton K. Gregg Train Shed Cyclopedia series reprinted portions of Freight Car Construction, by William Voss, first published in 1892. In this work, Voss, a Master Car Builder, makes the flat statement that freight cars as then being built were not going to grow beyond forty tons capacity; that the carrying limit of four wrought iron axles had been reached, and that future cars of greater capacity would either have six wheel trucks, or three four wheel trucks. He then presented concept drawings of a three truck coal gondola, the center truck supporting the car on lateral rollers.

Of course, this was right on the cusp of the adoption of steel axles, and four axle cars have grown threefold in carrying capacity since then, but my point is this: when evaluating a historic design, one has to disregard all that we have learned since, and view the design in light of what was generally known at the time. The fact that the design proved to be a failure certainly added to the knowledge base, but that failure could not have been predicted with certainty before someone tried it.

I think we'd all agree that in general, cars with six wheel trucks have superior riding characteristics, due to their longer wheelbase. If Herman Haupt would have designed the car with six wheel trucks rather than four trucks, we would be lauding it as the pioneer of a long line of innovation, rather than marveling at an obscure failure. But they didn't know that until someone tried it.

Jeff, this is the first video that the group has put out and produced on its own. I couldn't have done any better when I edited (and later assisted in filming of) our first news program in Photojournalism last year. Now, if the camera wasn't shaking the whole time, then I'd wager that the quality would be far better, but it's the first promotional film for the project. Now, if only someone could convince Sourcefed to do a story on this project...

There exists a drawing, I believe it was in Alexander's Civil War Railroads book that shows the layout of 2 trucks with a span bolster between riding on a single kingpin.

If one looks at photos of the car, either original or after re-trucking by the UP, there are two large nut and washer fittings at the bottom of the car side in line with the gaps between the pairs of trucks. The double rods is typical of a wood plank bolster; they angle up over the center sills like truss rods to help transfer the weight of the carbody to the center plate, and would seem to indicate that there was a weight bearing center plate at that location, in the middle of a span bolster. However, there is no structure to support side bearings between the trucks, so each truck must have had its own, possibly equipped with lateral rollers so that no side bearing clearance would be needed, meaning that each end of the car was supported at five points. The extra bolsters for the side bearings would transfer the load much closer to their outer ends, and thus not need the truss arrangement, and indeed, there is no evidence of additional cross rods at these locations.

Just how much clearance was designed into the side bearings, and how much weight was intended to be transferred directly from the body to the truck bolsters through them is, unfortunately, lost to the mists of time. I suspect it varied throughout the cars short career as a sixteen wheel vehicle. I suspect that the original intention was to transfer quite a bit of the weight through roller side bearings, similar to Voss' three truck coal car I mentioned above. This likely would have made the car ride quite well, but track quite poorly, especially on wide gauge track. I can see at some point the center plates being shimmed to cure the tracking problems, with the likely result that the car then rode poorly, and reports on the UP seem to confirm this. Of course, the obvious solution was to simply re-truck the car with a conventional two truck arrangement, and this was eventually done.

If Mr. Kloke builds the car as a four truck car for the sake of historical accuracy, it will be interesting to see if he re-discovers all these issues.

James,

Thanks for that information confirming the span bolster.

Apparently the span bolster is set rather low, so it is mostly obscured from view.

Here is a link to a side elevation drawing:

http://www.the2015lincolnfuneraltrain.c ... lo-res.jpg

There is some detail showing below the frame, and between the trucks, but that may be something flush with the side wall of the car rather than the span bolster center bearing.

Here is an interesting wooden display model construction project. It shows a span bolster, but this feature may not accurately modeled. One photo shows the plans fairly well in the truck area.

http://canteenbooks.com/building_lincol ... al_car.htm

I think this is an unusually handsome piece of rolling stock. The double trucks sure add to the appearance, if nothing else. But I suspect the motive for the four-truck design was for better stability. I can see how that would result from spreading the load out to double trucks through a span bolster.

Dennis,

I think I recall seeing a photo of a three-truck gondola. Was this Lincoln car designed by Herman Haupt? I have studied his Civil War railroad bridges.

I see those rod nuts centered on car side between the two trucks. The apparent connection between each truck and the car frame, must be some other type of feature rather than a pivot bearing. It will be interesting to see how Mr. Kloke develops the details. I suspect there are lots of unusual features in the configuration of the span bolster and the corresponding details of the truck bolsters and how they pivot on the ends of the span bolster.

I am particularly interested in truck and suspension design, because there was so much variety in details throughout history and a lot of experimentation.

Ron,

I think I've seen the design of the car attributed to Haupt. Maybe not all the intricate details, but the car was constructed by the United States Military Railroad, it was intended for the President, and Haupt was the commander.I would suspect he took some time from his busy schedule to look over what the shop had planned.

I don’t doubt that it was designed by Haupt. After seeing the exceptional beauty of some of his bridges and that of the Lincoln funeral car, I would say that they almost have to be connected to the same creator.