He already got it done. He called me tonight the results are in. TURNS OUT IT WAS A COMBINATION OF FACTORS. One was the water tanks like I suspected. Second was the truck design being a hollow Bolster it did not have the mass needed to stop hunting once it started. Last was the trackwork. What would happen according to his simulations 95% of the time is first the engines would hit a low spot and rock side to side getting the water sloshing in the tanks then once that was going the trucks would start to hunt keeping the first thing going and getting worse then throw in a curve and bang rear trucks on the ground. Was worse for them if coupled back to back like I suspected. The other 5% happened do to bad trackwork only given the RR's Finances at the time I could see that happening.
edbenton You are STILL talking about 16000 lbs of slosh at 2000 gallons at 79 MPH I did the calculations and you get APPROX 40 tons of force at 79 MPH. Now you put that amount of weight up high on rough track it could of help in the derailments. Also tank cars are loaded to the TOP and can handle the pressure of expanding liquids up to 100 psi for a Standard DOT 111 car. That is why you do not feel surge. Think of Surge as Slack Action. Yet once the Santa Fe got the Sdf40P's they rebuilt them because they had never had an issue with them and they served a long career and were just retired a couple years ago. I called my cousin a computer programmer since there is not enough data out there to see what happened he is writing code for me to run a simulation on what was causing the derailments on these units he told me I should have it done in about 6 weeks. He is doing it in his free time. BTW he works for EA Games and works on Sports game line so he knows his stuff. He will run it and send e the results.
You are STILL talking about 16000 lbs of slosh at 2000 gallons at 79 MPH I did the calculations and you get APPROX 40 tons of force at 79 MPH. Now you put that amount of weight up high on rough track it could of help in the derailments. Also tank cars are loaded to the TOP and can handle the pressure of expanding liquids up to 100 psi for a Standard DOT 111 car. That is why you do not feel surge. Think of Surge as Slack Action. Yet once the Santa Fe got the Sdf40P's they rebuilt them because they had never had an issue with them and they served a long career and were just retired a couple years ago. I called my cousin a computer programmer since there is not enough data out there to see what happened he is writing code for me to run a simulation on what was causing the derailments on these units he told me I should have it done in about 6 weeks. He is doing it in his free time. BTW he works for EA Games and works on Sports game line so he knows his stuff. He will run it and send e the results.
Hope his physics is better than yours!
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
You get anyload that is TOP HEAVY or put any heavy oblect such as Water TANKS for a Steam Genarator ABOVE what on a normal unit would be the CENTER OF GRAVITY you are going to have problems. Couple that with bad track from deferred maintance from lack of capital and then a hodgepodge of equipment that might not respond all the same when it came to braking forces and such and LOOK OUT.
Not just tank trucks are a problem. There is one such incident involving an air ride trailer of a famous furniture mover hauling electronics in the Boston area in winter. apparently it was icy that morning and the driver swears he exited the off ramp off 95 at less than the posted speed. Apparently the trailer air ride suspension kept leveling the trailer and the result was a fulll load of computer equipment on its side burning. The resulting claim was several millions of dollars. Of course they fired the driver an owner operator. I also hauled electronics at that time and many of the main frame computer equipment was top heavy at that time and can understand the drivers argument. I never lost a load but came close on a couple of occasions.
Al - in - Stockton
Timez I pulled tankers for a few months and it takes about 40 tons to tip one over. I have the charts someplace and 2000 gallons that weigh 16 grand moving at 79 mph would have that much force. Now that much surge may not seem like alot however you get it going side to side before it settles down you are getting into harmonic vibrations and next thing you know you are on your side. Why do you think tankers take most curves 5-10 mph slower if they are 1/2 full surge. I saw a loaded tanker moving at 60 mph on a wet road get slid into a ditch like some one picked it up and placed it there.
In an earlier reply, someone inquired about where the SDP40F-related derailments occurred. From the book I have, several occurred on BN trackage over which the California Zephyr travelled, and others occurred on former L&N trackage.
edbenton16000 lbs of slosh at 2000 gallons at 79 MPH I did the calculations and you get APPROX 40 tons of force at 79 MPH.
Let's have a look at that calculation.
+He is using the DESIGN Specs of the SDF40P including weight and were stuff was located he is also going to be using the track standards of the FRA for the speeds plus is going to be using various other things that could of have happened during the usage of the units. His design of the Modeled unit is BASED OFF THE BLUEPRINTS and SPECS so it should be accurate. He is also going to be using the standard maintance standards of the day for trackage 39 foot jointed rail and such. Yes it is not the same as the real life locomotive but it is better than nothing.
Please tell me how much height you suppose these tanks to have, since the frame seat was less than 7 feet above the railhead.
I have heard many explanations for the problems that the SDP40F's had...including the water theory, rail alignment and railhead contour, which by the way, the lines that comprise the Southern Region of CSX experienced most of the problems, and truck hunting, which although hunting has been a word that was used, it ceased when modifications were made to those trucks.
It could have been anything, I suppose, including your water theory. Doubt that, though, and the NTSB and Amtrak reports tend to discount that idea.
Save your scientific reports. The fact is that the locomotives were junk as passenger engines. The fact that Santa Fe did not have problems with them proves little, since they didn't derail on ATSF track, either, to my knowledge, nor on UP or SP. SCL, L&N and other Eastern Roads had the lion's share of the difficulties.
And actually, on a 100 car Oil Can, you do feel surge, whether you want to or not. After 31 years as a Locomotive Engineer, I believe I have earned at least the right to know about slack, if nothing else.
I doubt seriously that a computer program without the necessary raw track data is going to solve a mystery that has existed for this many years, but have fun.
Case closed. I have to go to work.
Hae to say it but a train isn't a truck...........
While the law of physics applies, there are several differences when you are talking about the forces required to throw (and that is what would have to happen) a 400,000 pound (OK, 380,000 pound) locomotive off the rails.
While actually OPERATING these locomotives, I neve felt anything resembling "water slosh" from the steam generators or tanks. Having run tank trains, and genuinely feeling fluid movement, your argument based upon a truckload of liquid does not make sense when looking at the amount of fluid you would haul and the weight of your truck vs the amount of water carried and the weight of a locomotive. The ratios are all off.
Here is what needs to be done. I know there are a couple SDF40P still around take them to the AAR test track. Pull the Cement weights out of the back end and put in the water tanks run them at various levels and get an answer as to WHAT was going on and end this. You put them back to back load 2000 gallons of water in the steam heat tanks and have them hit the curves on the test loop you will see how much surge there was and then figure out if that could of caused the derailments. Also make sure the tanks are clear that way the video from it will be awesome. Heck what do I know I only hauled stuff that would roll me over if MY BRAIN was not on the task at hand 100% of the time.
"From what I have read the SDP40F had NO water in the in the fuel tank area at all the entire supply was carried up high"
My description comes from the SDP40F service manual (1973 edition).
Paul,
The reason for the FP45's 'trailing' is due to the lack of cab signaling on them. The Milwaukee was planning on removing the trackside equipment and did not order the matching locomotive gear for the FP45's. The trackside system was not removed, and trains with a FP45 leading were limited to 79 mph, rather than the normal 90 mph between Chicago and Hastings, MN.
Would they ride as good as the E9's? Of course not. But they rode much better than the old worn out FP7's!
Ed,
The SDP40F's did have a partitioned underbelly tank and the carbody tank mounted ahead of the S/G skids. There were a number of possible issues;
No one will ever be able to get to 'root cause' of the problem, but the engine was really too much for passenger service on many routes. Note that all following N/A passenger engines are 4 axle. There really is no need for the extra dig of 6 axles, and with HEP - not extra weight with all of that water.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Al,
The NP passenger F's had the largest S/G available from EMD at the time, but so did a lot of railroads. I never saw extra water tanks packed in around the S/G's. What the NP did was as follows:
Several other railroads also used this pumping system, just not with the 'Water Baggage' cars. The NP used D/B's on their passenger F's and there was no room for the 600 gallon 'hatch tank'. That and the brutal Northern Plains winter required lots of steam heat for the trains.
It was also interesting that the NP used larger steam generators on there F units than other roads and added water tanks around the generators as well. These were up high in the Aand B Funits.Even this was not enough water to get them through the bad water districts in Montana and N. Dakota. There solution to the problem was a water baggage car as the first car behind the power and water was drawn from this to the steam generators or I believe continued to supply water to those tanks in the units.
Is there a listing of where, when and what roads the SDP40s were derailing on.
Al - in - Stockton.
We had a guest lecture at our local NMRA chapter meeting from a representative of the Milwaukee Road Historical Society, and there was a suggestion that the Milwaukee Road found the FP-45's to be rough riding and commonly placed them trailing in consists behind older, smoother-riding cab units. The slides showed at the meeting had one trailing in the back-facing direction.
The Milwaukee Road, owing to its precarious financial condition, was the poster child for "deferred maintenance" and the resulting track. Maybe the situation wasn't unique to the SDP-40F, and perhaps it was the combination of the tall water tanks and rough track. There also were not that many FP-45's -- only AT&SF and CMStP&P -- and only a handful at that, and on two roads, one with "good" track and one with less-good track. There was a whole fleet of SDP-40F's on a variety of roads to test fate more if one would jump the tracks.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
From what I have read the SDP40F had NO water in the in the fuel tank area at all the entire supply was carried up high they were designed that way so when the Feds pulled funding for Amtrak they could be sold to the Freight railroads and regeared fast. The FP45 had a fuel tank and water setup like that and had no issues. Why did the Santa Fe have no issues could it be the Santa Fe knew what they were in for with that design. The point is moot however but shows what happens when you let beaurcrats design a locomotive.
timz FWIW, the SDP40F had a water capacity of 3500 gallons: 2150 down there between the trucks and 1350 on deck. Wonder if the derailment investigators noted how full the tank was.
FWIW, the SDP40F had a water capacity of 3500 gallons: 2150 down there between the trucks and 1350 on deck. Wonder if the derailment investigators noted how full the tank was.
That's a good question. I don't recall if any of the tests used this as a variable. It's an interesting theory, but now moot.
I do recall that the majority of the derailments occurred on 2 deg curves, so that would leave out truck hunting as a cause.
Also, ATSF never banned or restricted Amtrak's SDP40F on their lines -- and nerver had a derailment. There was some supposition that the derailments were in part, due to bad track.
Very simple The SD40FP was a deriviative of the SD40-2 however the Steam Genarators and the tanks for them were on pallets in the back that way when Amtrak finally got HEP they could switch them out to Motor Gen sets to power the cars. This put the water weight up way to high and raised the CENTER OF GRAVITY. Now on the SDP35 FP45 SDP40 the hood verizon ordered by GN and SP the GP40P-2 and others the Fuel tank was split in HALF and water was carried in the other half. The F-3-9 were set up the same way EXCEPT for the ATSF who did not order their A units with the Stem Gens in the A units they instead put a 1200 gallon tank of water there that is why even on a SHORT Santa Fe passenger train you always saw a F unit A and B set on it. The FP7and 9 solved the lack of fuel tank size by lengthing the frame 4 feet just to carry water. Now why did the P30CH never have the issue the SDF40P had simple they NEVER HAD STEAM GENARATOR AND ALWAYS HAD HEP GENARATORS in them. I still feel that the water tanks played a huge part in the derailments that occured. To me the way they were designed is like hauling swinging beef packed in tight you are fine yet if they got loose from one another YOUR SCREWED.
So tell me why every other steam generator equipped locomotive from the steam era forward didn't derail?
edbenton Think of those water tanks as a tanker trailer used everyday going down the road. Just because you go thru that corner everyday at that speed with that load and never have an issuse does not mean SOONER OR LATER IT WILL NOT BITE YOU IN THE BUTT. Take it from someone that pulled tankers and you RESPECT THEM 100% OF THE TIME OR YOU WILL BE ON YOUR SIDE. All it takes is that liquid to get going and your DONE and on your side. The problems with the SDF40P's happened when they were coupled back to back and then the water tanks were closer to each other causing more surge in them at the same time. When that happened you could get and occislation going that nothing would be able to stop.
Think of those water tanks as a tanker trailer used everyday going down the road. Just because you go thru that corner everyday at that speed with that load and never have an issuse does not mean SOONER OR LATER IT WILL NOT BITE YOU IN THE BUTT. Take it from someone that pulled tankers and you RESPECT THEM 100% OF THE TIME OR YOU WILL BE ON YOUR SIDE. All it takes is that liquid to get going and your DONE and on your side. The problems with the SDF40P's happened when they were coupled back to back and then the water tanks were closer to each other causing more surge in them at the same time. When that happened you could get and occislation going that nothing would be able to stop.
I read an internal report long ago that the HTC trucks were delivered without proper lateral stabilization and that the unusual weight distribution of the locomotive caused truck hunting at high speed. In at least one, and possibly more, of the derailments, the generators' tanks were less than half full.
Having worked on them, I can tell everyone here that they rode rougher than any locomotive I have been on before or since, and they kicked like an Army Mule. Several times I was thrown from my seat while on them at speed.
That brings up an interesting point, regarding the orientation of the diesels in a passenger consist. More often than not, I see Amtrak locomotives facing the same direction. That would seem to make the most sense in-case they had some type of failure in the lead engine, they could swap positions without having to wye or turntable the secondary. An Amtrak conductor once told me that is the preferred arrangement.
However, I have seen Genesis engines on the Empire Builder arranged back-to-back on several occasions. Why would the railroad go with such an arrangement? Perhaps they figure a P42DC hasn't sufficient pulling power anyway to haul a 14-car train plus a deadhead locomotive? Surely this wouldn't have been the case with the SDP40F's?
I'm surprised the SDP40F's were arranged that way especially with the location of the water reservoirs.
At one point in time, I'd read every test report there was on SDP40Fs. None of them ever found even a smoldering gun, much less a smoking one..... There were even tests that ran the same track with the same consist at the same speeds +/-...nada!
Yes the F40PH's were all HEP - that much I know.
What about the water slosh theory (from one of the Diesel Spotter's Guide books)?
The derailments happened on sharp curves, presumably not near the max track speed. The speculation goes that they had these big carbody water tanks, and when half full entering a curve could set up and oscillation of the water sloshing around in the tank that caused the locomotive to spread the rails.
We will probably never know unless someone has a gazillion dollars to grab one of the old SDP-40F's that might be around and to put water tanks back in them. But the F40PH's were all HEP and didn't have steam water tanks, no?
There was lots of testing, but never any definitive verdict. Testing did not reveal any dangerous behavior, but it did show they weren't the best riding locomotives ever built, either.
I'm curious to know if there was ever a final, definitive answer regarding the investigations into the cause of the Amtrak derailments involving the SDP40 locomotives? I know they were retired from service after it was suspected that the excessive lateral sway may have been a contributing factor in rail being spread (causing some railroads and later the NTSB to impose speed restrictions). From what I can discern from the information I've read so far, they seem to have thought the internal design created a higher center of gravity that lead to the swaying on the less-than-excellent-condition ROWs.
Has any definitive answers been reached? Maybe after the units were replaced by F40PH's the matter was considered resolved?
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