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Question about construction of hopper cars.

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Posted by CShaveRR on Tuesday, November 27, 2018 2:33 PM

Not really--a lot of those "porches" have little headroom and no floors.

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Posted by rrnut282 on Tuesday, November 27, 2018 10:40 AM

Murphy Siding

....Those hoppers have some of their structure built out beyond the ends of the main box that holds the rocks. It makes the cars appear to have little porches on both ends. I've never understood why they were designed that way....

If you think about it, all slope-end hoppers have a "little porch" on them.  On most it is hidden behind ladders and end bracing.  

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Posted by BaltACD on Monday, November 26, 2018 6:00 PM

PNWRMNM
 
Murphy Siding
 
oltmannd

Truck hunting threshold speed increases with car length.  Not an issue with loaded cars.  Short, light, empty cars would be very prone to hunting at typical train speeds.  That may be why aggregate hoppers are longer than would appear necessary. 

Would this also come into play if some of the D&I track is jointed track with a fair amount of dips in it? 

No. Truck hunting happens at high speed, some frt cars over 45 MPH, A few track irregulaties tend to disrupt the hunting motion, which is the truck turning from side to side, which makes the car body shake and rattle. Empty cars are most at risk for hunting.

Jointed rail often has the joints beat down, which are cross level deviations. Harmonic rocking of cars with 39' or so truck centers can become dangerous at speeds of about 15 MPH, because it sets up a harmonic rocking. In extreeme cases the cars can rock themselves off the track. 25 MPH is safer than 15. Nominal 100 ton grain cars are the most common examples.

Chessie System in the late 60's and early 70's had a TTSI about 4700 cu.ft. and greater Covered Hoppers operating on 6 degree or greater curves - if a train containing them could not maintain a speed above 25 MPH, speed was to be held below 15 MPH.  The TTSI was the result of a number of rock off derailments around the system

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Posted by PNWRMNM on Monday, November 26, 2018 4:14 PM

Murphy Siding

 

 
oltmannd

Truck hunting threshold speed increases with car length.  Not an issue with loaded cars.  Short, light, empty cars would be very prone to hunting at typical train speeds.  That may be why aggregate hoppers are longer than would appear necessary.

 

 

 

Would this also come into play if some of the D&I track is jointed track with a fair amount of dips in it?

 

 

No. Truck hunting happens at high speed, some frt cars over 45 MPH, A few track irregulaties tend to disrupt the hunting motion, which is the truck turning from side to side, which makes the car body shake and rattle. Empty cars are most at risk for hunting.

Jointed rail often has the joints beat down, which are cross level deviations. Harmonic rocking of cars with 39' or so truck centers can become dangerous at speeds of about 15 MPH, because it sets up a harmonic rocking. In extreeme cases the cars can rock themselves off the track. 25 MPH is safer than 15. Nominal 100 ton grain cars are the most common examples.

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Posted by Murphy Siding on Monday, November 26, 2018 9:20 AM

oltmannd

Truck hunting threshold speed increases with car length.  Not an issue with loaded cars.  Short, light, empty cars would be very prone to hunting at typical train speeds.  That may be why aggregate hoppers are longer than would appear necessary.

 

Would this also come into play if some of the D&I track is jointed track with a fair amount of dips in it?

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Posted by ericsp on Sunday, November 25, 2018 11:50 PM

The slope of the end sheets appears steeper than most hoppers.

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Posted by zugmann on Friday, November 23, 2018 10:54 PM

mvlandsw
Keeping it on the porch of your SD40-2 making it easier to get to.

Good luck getting one of those anymore. 

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

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Posted by tree68 on Friday, November 23, 2018 10:53 PM

mvlandsw

 

 
zugmann
 
Murphy Siding
It makes the cars appear to have little porches on both ends. I've never understood why they were designed that way.

 

Where else are they going to put the BBQ grill?

 

 

 

Keeping it on the porch of your SD40-2 making it easier to get to.

 

Beats cooking on the engine block...

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Posted by mvlandsw on Friday, November 23, 2018 10:39 PM

zugmann
 
Murphy Siding
It makes the cars appear to have little porches on both ends. I've never understood why they were designed that way.

 

Where else are they going to put the BBQ grill?

 

Keeping it on the porch of your SD40-2 making it easier to get to.

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Posted by MidlandMike on Friday, November 23, 2018 9:42 PM

I understood this to be the rapid discharge design, which has almost the entire bottom over hopper doors.

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Posted by zugmann on Friday, November 23, 2018 5:22 PM

Murphy Siding
It makes the cars appear to have little porches on both ends. I've never understood why they were designed that way.

Where else are they going to put the BBQ grill?

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any

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Posted by Euclid on Friday, November 23, 2018 5:13 PM

 

That hopper car is no different than grain hoppers except that grain is less dense than aggregate, and can therefore extend its volume over the “porch.”  The trucks have to be spaced far enough apart to allow the hoppers to empty.  But, because the cargo is so dense, there is no need for extending its loading over the trucks. 

 

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Posted by PNWRMNM on Friday, November 23, 2018 3:32 PM

Another issue is bridge loading in pounds per foot of car. Look on BNSF's web site for weight limit by line. I suspect the light ones are mostly due to light loading bridges.

Also look at the slope sheet angle, which is quite steep. The bottom of the sheet is such that the unloading gates are not far from the inside wheels. I do not see any excess length if you look low.

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Posted by oltmannd on Friday, November 23, 2018 10:57 AM

Truck hunting threshold speed increases with car length.  Not an issue with loaded cars.  Short, light, empty cars would be very prone to hunting at typical train speeds.  That may be why aggregate hoppers are longer than would appear necessary.

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by jeffhergert on Friday, November 23, 2018 10:24 AM

L. G. Everist had other aggragate hoppers with "porches" before.  I haven't seen any for awhile.  They looked more "boxy" like the trinityrail hopper, but older. 

https://www.trinityrail.com/productdetails.aspx?id=26&catid=25 

I've seen pictures of aggragate hoppers with the porches dating from the 1960s.  I don't know that I've ever heard why the design is popular.

Jeff 

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Question about construction of hopper cars.
Posted by Murphy Siding on Friday, November 23, 2018 7:37 AM

Image result for L.G. Everist 2006 Built Rapid Discharge

(I hope this photo of an L.G. Everist hopper car shows up on your screen.)

      Every day I see trains of hopper cars filled with pink rock going by on Dakota & Iowa trains. About a dozen years back, the L.G. Everist quarry, which owns the railroad, bought a bunch of new hoppers. Those hoppers have some of their structure built out beyond the ends of the main box that holds the rocks. It makes the cars appear to have little porches on both ends. I've never understood why they were designed that way.

     Every other hopper they have is of traditional design, where the front of the box is essentially the end of the car. It seems like these newer cars would be longer, making for longer trains with no offsetting advantage.

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