I saw one of these on a siding recently and I was curious about them. Mostly the fact I don't see how the shorter centerbeam is practicall. Can someone explain the logic behind the design of these cars?
DavidH66I saw one of these on a siding recently and I was curious about them. Mostly the fact I don't see how the shorter centerbeam is practicall. Can someone explain the logic behind the design of these cars?
Can someone explain the logic behind the design of these cars?
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Two things to remember about shipment by rail or any other means of transportation.
There are cubic foot restraints and there are weight restraints. The 'ideal' vehicle brings the two factors together.
A present day coal hopper is designed for 100 tons of COAL when loaded to 'full visible capacity'. Were that same car to be loaded with iron ore, to the same visible capacity the car woul be well on it's way to having 200 tons of load. By the same token, were it to be filled to the same capacity by expanded styrofoam beads there would probably be less than 25 tons in the car.
Shipments either weigh out or cube out to fill their transporatation vehicle. If you look at the weight limits on the various sizes of containers 20 foot, 40 foot, 48 foot and 53 foot you will notice that the limits on each are nearly the same (within several hundred pounds).
The shorter center beam, reduces the tare (light weight) of the car and thus creates more load weight before the car exceeds its maximum gross weight. If the tare weight of a high center beam car is 62K and its maximum gross weight is 200K which leaves 138K for revenue loading. If the short center beam car has a tare weight of 56K that allow 6K more loading and therefore more revenue within the same 200K gross weight limit.
Would be interesting to know if the added costs for all the fabrication of the X's is saved by the reduction in steel used - likely not, IMHO.
However, the added revenue from the additional payload as BaltACD said above probably makes up for it.
- PDN.
As I see it, the main difference between the Flexibeam and other center-beam cars is that the center-beam is lower on the former. Is the "load mark" absolute, or can you load higher if your commodity is light-weight? I do see that securing the load may be a bit tricky if you load higher. If the "load mark" is absolute, it seems to me that they could have just made the cars shorter, and the center beam would not have to be as beefy. And why the name Flexibeam? It can't be that the beam is flexible.
_____________
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Paul of CovingtonAnd why the name Flexibeam?
Could be that they intended the car's uses to be "flexible..." And it is a centerbeam flat.
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These Flexibeam cars are in fact heavier than a conventional Center-beam car, by about five tons. They are also longer by about eight feet, and lower by almost a foot.A lot of the problems that I saw with the Center-beam cars when I was at work was that the empty cars had an extremely high center of gravity. A lot of string-lining derailments involved empty Center-beams. The Flexibeam design certainly addresses this problem. It's possible that the reduced load limit is more of a reflection of the cars' handling capacity (i.e., the old Center-beams may not have been able to be loaded to their load limit).There have not been many center-beam cars of any sort built in the past ten years. When the market returns, the Flexibeam may well be the new standard.
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CShaveRRA lot of the problems that I saw with the Center-beam cars when I was at work was that the empty cars had an extremely high center of gravity. A lot of string-lining derailments involved empty Center-beams. The Flexibeam design certainly addresses this problem.
They also tend to hunt badly at high speeds when empty, and that has caused derailments as well. After one such incident a few years ago CN imposed a 45 mph speed restriction on empty centrebeams, but it has since been lifted (not sure why).
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SD70M-2DudeThey also tend to hunt badly at high speeds when empty, and that has caused derailments as well. After one such incident a few years ago CN imposed a 45 mph speed restriction on empty centrebeams, but it has since been lifted (not sure why).
They also have a habit of being blown back *up* the hump in heavy winds. Not really a problem on CSX anymore, I guess.
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The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
zugmann They also have a habit of being blown back *up* the hump in heavy winds. Not really a problem on CSX anymore, I guess.
CN runs a daily "unit" train of them from Chicago to Prince George (M347), which is often 10,000' or longer and 100% empty centrebeams.
That train never hits track speed, even when pulling it downhill in notch 8. I remember a new trainmaster puzzling over how this lightweight, empty train somehow used more fuel than grain loads.
Crews refer to it as "dragging the sails", the harder you pull, the harder it pulls back.
SD70M-2Dude zugmann They also have a habit of being blown back *up* the hump in heavy winds. Not really a problem on CSX anymore, I guess. CN runs a daily "unit" train of them from Chicago to Prince George (M347), which is often 10,000' or longer and 100% empty centrebeams. That train never hits track speed, even when pulling it downhill in notch 8. I remember a new trainmaster puzzling over how this lightweight, empty train somehow used more fuel than grain loads. Crews refer to it as "dragging the sails", the harder you pull, the harder it pulls back.
Johnny
[quote user="DavidH66"]
BNSF 564103
Flat Car Mechanical DesignationFBC Outside Length089 ft 03 inAAR Car Type CodeF484 Outside Extreme Height14 ft 09 inInside Length00 ft 00 in Outside Extreme Width09 ft 09 inInside Height00 ft 00 in Height of Extreme Width03 ft 07 inInside Width00 ft 00 in Upper Eaves Height00 ft 00 inSide Door Height00 ft 00 in Upper Eaves Width00 ft 00 inSide Door Width00 ft 00 in Lower Eaves Height00 ft 00 inSide Door Type Lower Eaves Width00 ft 00 in
Plate ClearanceC Star StencilLCompartments Trans CodePOutlets Trans Cond CodeLining Floor TroughRoof Type Floor StrengthDraft Gear10 ArticulatedCubic Ft Capacity00000 cu ft Max Weight on Rail286000 lbs.Nominal Capacity000000 lbs. Tare Weight070200 lbs. Load Limit215800 lbs.
Thanks, SD70-2dude, you just answered a question of mine, as to what this train is all about. I railfan the area around Midway siding, watched one yesterday, and it was going slower than other trains. Now I know.
Mike.
My You Tube
tree68 Paul of Covington And why the name Flexibeam? Could be that they intended the car's uses to be "flexible..." And it is a centerbeam flat.
Paul of Covington And why the name Flexibeam?
This is embarrassing but I thought it had some form of articulation when I first saw the name.
The manufacturer also uses the term Hybrid ..
http://www.freightcaramerica.com/index.php/manufacturing/
The FleXibeam™ Hybrid Center Beam Car is the optimal car for hauling forest and steel products.
I've often wondered whether bulkhead cars (including all sorts of Center-beam cars) could be constructed with a pattern of holes in the bulkheads--not large enough to weaken the structure or compromise the load, but enough to lessen the resistance of empty cars. I know that empty bulkhead cars are limited in speed,and I've seen them blow back out to foul a yard lead (interesting--that sailing capability never seemed to work in our favor!).
CShaveRR I know that empty bulkhead cars are limited in speed,and I've seen them blow back out to foul a yard lead (interesting--that sailing capability never seemed to work in our favor!).
It's likely an effect similar to I2R resistance. The direct problem isn't the resistance of the 'bulkheads' so much as the vortex and turbulence generation around all the elements of the structural truss in the centerbeam, interacting with the larger trapped vortices in the 'corners' between the beam and the inside face of the bulkheads (which might, otherwise, tend to smooth both the incident and quartering airflow in the same way that a closed pickup bed does compared to one with a partially-open "drag-reducing" tailgate -- more "holes" are DEFINITIVELY not the right answer here!) Be fun for someone with an IR camera to observe the actual airflow patterns around one of these things at various speeds, including what I suspect will be development of periodic vortex shedding a la Tacoma Narrows Bridge at critical speeds ... corresponding, unsurprisingly to those in the know, with the reported severe 'hunting' there.
I'd be interested to see what a simple application of sheathing (perhaps like the material used for those trailer skirts Shadow the Cat's Owner despises so much) to both sides of the centerbeams would do. Or the equivalent of one of those expandable 'trailer tail' origami things in each corner, deployed to shape the trapped vortices better but have minimal effect on useful load space when stowed.
CShaveRRI've often wondered whether bulkhead cars (including all sorts of Center-beam cars) could be constructed with a pattern of holes in the bulkheads--not large enough to weaken the structure or compromise the load, but enough to lessen the resistance of empty cars.
Problem is if the holes allow any of the cargo to escape (things like steel rods, for example), then you are creating a shiftable load with its requirements.
Here is a patent from 1969 for a foldable bulkhead ... Interesting concept.
https://www.google.com/patents/US3464368
Sure..why not have them fold. Even a centrebeam could be made to fold down. Then it would lay flat on what is now just a flat car. It could be done hydraulically or manually. I suppose the man hours in delay getting setup or just another set of things that require maintenance or something to go wrong is a factor.
Aren't those air-foils on top of semi cabs supposed to fold down when they aren't hauling a trailer? I see a lot that are still standing.
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zugmann Problem is if the holes allow any of the cargo to escape (things like steel rods, for example), then you are creating a shiftable load with its requirements.
The holes might be big enough, but if we're worried about loads like steel rods going through the holes, loads of steel don't ride up too high in the cars--perhaps the bottom few feet could be left solid. Higher up on the bulkheads...well, I'm not worried too much about the toothpicks.
MiningmanSure..why not have them fold. Even a centrebeam could be made to fold down.
There are centerbeams that are fairly solid, or there used to be. Most nowadays seem to be more, shall we say, "lacey." The solid versions would be hard to fold...
I would think that the bulkheads would be the main issue. Building versions that would lay down would be fairly easy - controlling that movement would be the challenge. Cranking them up might involve a cable/winch system that could be run with, say, an impact wrench, or even by hand. Most loading facilities would be able to handle raising them. Keeping them under control when lowering would be where one would encounter issues. Depending on where they are hinged, you don't want to just drop them.
Securing them in the raised position can't be too hard. If the Navy can hinge the wings on airplanes and secure them well enough for high-G maneuvers, and shipping containers can be locked together easily, that solution may be one of the easier parts...
tree68 Miningman Sure..why not have them fold. Even a centrebeam could be made to fold down. There are centerbeams that are fairly solid, or there used to be. Most nowadays seem to be more, shall we say, "lacey." The solid versions would be hard to fold... I would think that the bulkheads would be the main issue. Building versions that would lay down would be fairly easy - controlling that movement would be the challenge. Cranking them up might involve a cable/winch system that could be run with, say, an impact wrench, or even by hand. Most loading facilities would be able to handle raising them. Keeping them under control when lowering would be where one would encounter issues. Depending on where they are hinged, you don't want to just drop them. Securing them in the raised position can't be too hard. If the Navy can hinge the wings on airplanes and secure them well enough for high-G maneuvers, and shipping containers can be locked together easily, that solution may be one of the easier parts...
Miningman Sure..why not have them fold. Even a centrebeam could be made to fold down.
Making either or both the bulkheads and center beams moveable would increase the maintenance costs for the cars as well as creating another point(s) of failure that would decrease the availability of the cars for customer use.
If it is made by man it will fail, the only questions are when and how. Was at a race and a high dollar car in a high dollar class was stuck on the elevator gate of it's 53 foot trailer/workshop. The car missed the start of the race, where it had qualified on the Pole by a second or more. By the time the mechanics rectified the condition and go the car down on the ground the race was in lap 5 or so. If it is made by man, it will fail at the worst possible moment.
MidlandMikeAren't those air-foils on top of semi cabs supposed to fold down when they aren't hauling a trailer? I see a lot that are still standing.
Almost all the ones I know of are one-piece, fiberglass/Cycolac or blow-molded, and do not fold. They encounter frontal resistance rather than just vortex-shedding like a Kamm tail, so have to be stronger and better frames and anchored than a folding trailer arrangement. I believe inflatables have been tried with a dismal range of potential failures.
I have advocated over the years for an inflatable internally-strapped tail that would use brake air; this would provide proper rear streamlining for not just the fixed top shroud but the rear wall of a bobtail. I suspect, though, if there were an actual market for this you'd see at least one on the road by now. Of course I'm still waiting for the widespread provision of biparabolic 'stick-on' nosecones for the bluff front wall above the cab roof on straight trucks, too...
zugmann CShaveRR I've often wondered whether bulkhead cars (including all sorts of Center-beam cars) could be constructed with a pattern of holes in the bulkheads--not large enough to weaken the structure or compromise the load, but enough to lessen the resistance of empty cars. Problem is if the holes allow any of the cargo to escape (things like steel rods, for example), then you are creating a shiftable load with its requirements.
CShaveRR I've often wondered whether bulkhead cars (including all sorts of Center-beam cars) could be constructed with a pattern of holes in the bulkheads--not large enough to weaken the structure or compromise the load, but enough to lessen the resistance of empty cars.
Before you get to loaded problems, adding holes will vastly increase effective drag on an unloaded sequence of bulkheads. This can even be seen with reference to pickup tailgates.
You would think there would have been some interest in operational aerodynamics after the fiasco with the effect of 'lightening holes' in plate centerbeams... but apparently not yet.
Paul_D_North_Jr Would be interesting to know if the added costs for all the fabrication of the X's is saved by the reduction in steel used - likely not, IMHO. However, the added revenue from the additional payload as BaltACD said above probably makes up for it. - PDN.
Thanks to Chris / CopCarSS for my avatar.
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