Why flat side on new tank cars?

[Walter Clot]

I've noticed some new tank cars in our area.  Some have about a 1 foot flat section running along each side.  What is the purpose or meaning of this?

Walter in Columbia

[Frisken]

Capacity increase? Since you can't exactly increase width adding a foot on the height is probably a good way to increase capacity, however some concerns about center of gravity must ofc be raised!

 

Greetings Hans 

[ndbprr]

A flat side in place of an arc would decrease capacity.  I thought it was done to avoid exceeding the allowable car width.

[steemtrayn]

It's probobly a long car, and the flat section makes the car narrower in the middle to allow clearance in tight spots on sharp curves.

[stokesda]

I've seen the same cars in my area, and IIRC, it's only a section out of the center half or so of the car that's got the flat side, so it doesn't seem that the purpose is to make the overall car narrower (i.e. the ends of the car are still full diameter and stick out past the flat section).

I could be wrong about that, though?

EDIT: I just re-read the post above - if it's a long car, it would make sense if it was narrower in the middle section to make clearance on curves. That makes sense. Still would be nice to know if that's the real purpose, though.

[Sperandeo]

Yes, as others have speculated, the flat-sided tanks allow greater clearance for large-diameter tanks on the inside of sharp curves. The flat areas don't extend to the ends because the overhang on curves decreases as you get closer to the trucks. Tank cars with this feature have actually been around for a few years now.

So long,

Andy

[markpierce]

Egad!  How long are these car?  Sounds like an expensive solution to increase capacity!

Mark

[Frisken]

Yeah capacity increase as i said.

Only way when the tank car has reach the allowable width is the increase height and thus hi-cube's, double-stacks 3-floor car cars etc. 

Recepie:

1.Take one ordinary full sized tank car

2.Cut it along the middle vertically

3.Insert 1 foot high panels into cut, veld it back together.

4.Enjoy another few gallons of transportables.

 

[Walter Clot]

Yeah capacity increase as i said.

Only way when the tank car has reach the allowable width is the increase height and thus hi-cube's, double-stacks 3-floor car cars etc. 

Recepie:

1.Take one ordinary full sized tank car

2.Cut it along the middle vertically

3.Insert 1 foot high panels into cut, veld it back together.

4.Enjoy another few gallons of transportables.

Frisken,  In point 2 you said vertically!  Don't you mean horizontally?

Thanks everyone for your input!

[Frisken]

Yes ofc, late night posting ... 

[Sperandeo]

I don't think everyone is seeing this clearly. The capacity of these big tank cars comes from having long tanks of large diameter. The flat sides do actually decrease that capacity somewhat, but provide the desired clearance on sharp curves. So overall, if you want a big tank car that you can use on sharply curved industrial tracks, flat sides are a way to get there. You could also use an even longer tank of smaller diameter, but then you'd be able to put fewer cars into a given length of track.

So long,

Andy

[Walter Clot]

I'm having a tough time believing it is for clearance.  I've never seen a tank car that the tank hung over the under frame.  If it doesn't, what good would it do to reduce the diameter of the tank?  Since the "flat" section is only about one foot high along the center of both sides of the car from front to rear, it couldn't be changing the width on each side that much!  Think of the diameter of the tanks and then flatening one side by one foot!  How much would it reduce the width?

Perhaps there is someone out there who works for a railroad who could tell us, "Why?"

[ericsp]

Here is an excerpt from page HC-16 of the October 2007 Official Railway Equipment Register.

"The maximum widths shown are based on the swingout at center of car which usually governs. Maximum allowable width of car, other than at center of car is shown on Plate D. On cars with long overhangs, the swingout at ends of car must also be checked."

The flat panels are probably so that the car will fit into Plate C.

Here is a link to a photograph of one of those tankcars.
http://www.railcarphotos.com/PhotoDetails.php?PhotoID=14993

[Walter Clot]

Eric,  Thanks for the photo and information.  I guess my eyes aren't sharp enough to see the flat part, (I'll be 72 tomorrow) but I'll take you word for it.

I passed the area where the cars were today and got out to look at them closer, but they weren't the ones with the flat section, but seemed to be just as big! 

I wonder if there are models of these cars yet!

Thanks everyone else for your input.  I'll check this forum from time to time to see if anything else shows up.

[ericsp]

Here is a better photograph.
http://www.railcarphotos.com/PhotoDetails.php?PhotoID=18822

When you look at cars, you will notice they have a plate designation, usually by the reporting marks. The higher the letter, the more restrictive the interchange. The builders probably want these cars to fit into the Plate C. My guess is, in order to do this they probably had to shave off just a little bit of width, but only toward the middle of the car. They probably figured the bast way to get the car to fit into the Plate C category is to make the shell (but not necessarily the tank) flat at the middle. There may be cars that are very close in size but with a slightly smaller diameter tank or they are short enough that they fit into Plate C.

There is one thing that I found interesting. I noticed that these UTLX tankcar have the rails at the bottom designed to discourage people from going underneath the tankcar. These appear to extend out beyond the tank, although they may not. If they do, then the flat panel would seem to do nothing for clearence.

Happy birthday. Your 6th birthday must have been interesting.

[Walter Clot]

Eric,  Great picture!  Thanks for taking the time.  This is what I see in our area from time to time.  Have you seen any in HO model?

Thanks for the birthday wish.  It was good. 

[Dave-the-Train]

I've had cars with side panels like that...

[ericsp]

You will have to modify a Walthers car to model on of these.