[Pete Thornton]

I suspect this has been covered before, but as it was a nice day to take some photos, (and we all know how you folk love pictures,) I decided to post my findings.

I splurged at the weekend and bought an Accucraft flat car:

Just like the one in this "manufacturers photo", mine has a upward curve, somewhat more pronounced.  Jeff Redeker, who has a few of them, was talking about putting his in the oven with a brick on top.  I figured I should put it in the sunny window of my office, but then I remembered I have a floor heater along the front of the window.  So the heater got turned on, and I grabbed a few heavy bits - my drill, a piece of marble from a bathroom, and a box of zincs waiting to be installed on my boat.  I took the trucks off the flat and supported the end beams using some 1x1s and rubber 'feet'. 

It worked!  How's that for a sway-backed flat car....

HOWEVER, I discovered the truck bolsters had been significantly damaged by the heat - and it turned out to be the truss rods, which actually work on this car.  The following picture shows the bolster (top) and the ends of the trusses that I have bent flat in an attempt to fit them under the bolster.

The truss rods had a right-angle end behind the bolster.  Here's the other end of the car, with the truss rods loose, because there is no bolster at the other end of the car.

Finally, here's the turnbuckle, which is threaded.  You'll note the unpainted brass where I unscrewed the truss in an attempt to make it go back under the bolster.

I guess I'll have to solder something on the end of the rods to make them fit - seems too much of a hassle to unscrew them all.

I'll post a photo of the finished flat when I get it back together again....

 

[Spule 4]

And I got upset when I melted the roof of a $10 HO passenger car drying the roof paint about 12 years ago......

 

[Doug C]

Are you sure this line of  protos'   were  not  seemingly  bent  upwards ?  

The reason I toss that out  . . . have you ever noticed  flat bend trailers rolling down the highway ?     They all tend to be bent upwards due to the heavy load to come !!  If they are flat (unloaded) they're likely past their safe operating specs !


just a thought  . ..
doug c

 

[llynrice]

Hi Pete,

That arch may be deliberate.  If you look at a flat-bed trailer with no load on it, it will almost invariably have a very noticeable arch to it.  When such a trailer is fully loaded, it's quite straight.  This seems to be necessary to help the trailers to carry very heavy loads safely.  It wouldn't surprise me if railroad maintenance shops also tended to crank the truss rods pretty tight to allow for heavy loads.  Looks as if adjusting the turnbuckles would be the most viable option -- albeit tedious work.

Llyn

 

[vsmith]

There would be a bow but only if it was a spanking new car, after any amount of time it would likely look much closer to the after photo, which I think looks better.

But this is a good heads up anyone to remove those trussbars before anyone else tries this modification.

 

[CJGRR]

they were built with a arch to handle stressful loads......

 

[Pete Thornton]

Posted By Spule 4 on 02/19/2008 3:48 PM
And I got upset when I melted the roof of a $10 HO passenger car drying the roof paint about 12 years ago......


Let's see, after 12 years, that would be about $20 now?  The Accu flat cars can be bought for about $45, so I'm not too worried about making a mess of it.

I take everyone's point about it being tightened to curve upwards to make sure it handled the loads, but an older car would have sagged a little.  And my curve was significantly worse than the one in the 1st photo.

I don't think you can adjust the turnbuckles to 'correct' the curve (unless you plan to carry a 50lb transformer that will seriously bow the center!)  
 - the curve is probably moulded in to the plastic when the car is made,
 - the turnbuckles may not be threaded left/right, so you have to take the rods out of the bolsters to turn them,
 - the planks through the turnbuckles seem to be cast with the buckle, so you can't adjust the individual turnbuckle.

 

[Sourdoh]

I noticed a bow in my AMS Flatcar when I got it and was delighted that they got the preloading correct. A new Flatcar would be trusssed in a slight bow for the same reasons stated above about semi trailer flats. If it is bowed upward without a load it will bow to level under load. If it is level when empty it will bow downward under load, causing slacked truss rods when the load it removed. I don't do much dicking around with my roling stock (other than weathering) because I don't want to waste money by ruining anything. Hey, $45 is $45!

 

[aceinspp]

Yep bows are put there for a reason.  Leave well enough along cost to much to screw up  nice car like that.  Later RJD

 

[FH&PB]

John Clark, who designed the stock car kit for Hartford Products, also did a very small run of "humped" stock cars. He had noticed that unloaded cars appeared bowed upwards and reproduced that by laser-cutting the parts to the deformed shape.
Still, I like to idea of giving a car some "sway-back", too, to show long use. Too bad the car didn't cooperate fully!