Overmod There was a collateral issue with ride quality, perhaps more with primary than secondary suspension action, with the SDP40Fs, culminating in one report I heard second- or third-hand about an engineer breaking his coccyx on the seat (not at all funny) which simply shouldn't happen on a passenger locomotive. I think Mr. Goding has discussed some of the issues with the truck design (I wish I could recall the precise technical elements that were 'lacking' but dimly remember them as involved with lighter unsprung mass) and what was done to remediate that part of the concern.
There was a collateral issue with ride quality, perhaps more with primary than secondary suspension action, with the SDP40Fs, culminating in one report I heard second- or third-hand about an engineer breaking his coccyx on the seat (not at all funny) which simply shouldn't happen on a passenger locomotive. I think Mr. Goding has discussed some of the issues with the truck design (I wish I could recall the precise technical elements that were 'lacking' but dimly remember them as involved with lighter unsprung mass) and what was done to remediate that part of the concern.
I also heard stories of engineers unable to stay in their seats during rough ride events. When the HTC truck was released in production in 1972, it had a quite stiff vertical rubber compression pad secondary suspension to limit pitching of the truck frame during high tractive effort to minimize the weight shift between axles that occurs as a result of the motor nose forces. As the rubber pad was short, only about 3" tall, it was also stiff in the lateral direction which led to complaints of rough lateral ride when the lateral stops hit after the limited lateral travel of +/- 1.25" was reached. Three changes were made to fix the ride issue, in 1974 as I recall, consisting of 1) changing the rubber durometer to soften the vertical and lateral spring rate by about 40%, 2) opening up the lateral travel to +/-1.75 inches, and 3) adding lateral dampers between the truck frame and bolster. While not as good a ride as the SD Flexicoil truck which preceded it, the ride was improved to the point the complaints largely went away. Eventually, yaw dampers were added in the late 80's for customers complaining of truck hunting.
I've read comments that the hollow bolsters were the cause of the problems on the SDP40F's but they had nothing to do with it. The lighter bolsters lowered the yaw moment of inertia of the truck assembly which is good for hunting stability; laterally, the mass of the bolster is part of the carbody mass so it doesn't matter if the weight is in the bolster or carbody.
My personal opinion is that the HTC was not suited to 90 mph running and the SD Flexicoil truck as on the F/FP45's would have been a better choice for Amtrak. I did not work in the truck design group until 1982 so had no role in that decision, but I had enough problems at the time with exhaust silencer fatigue cracks on the SDP's and F40C's, the first production locos to get exhaust silencers.
Dave
timzBut years before, SFe did have some sort of trouble with U28CGs and/or U30CGs. Wonder if that had anything to do with water -- didn't DOT run its U30C at 120 mph on SFe around 1974?
This reminded me of the fun I had hearing 'war stories' from a senior GE engineer while we were on vacation in Tortola BVI in the early Seventies. (He is the one who recounted the story of the three IR detectors looking at the critical center bearing in one of GE's turbofan engines -- designed without recognition that what was passing the bearing had a different refractive index for IR, so when the bearing got hot there was no alarm from the triple redundant system... and the bearing would seize up with lamentably predictable results.)
He recounted a story about the initial testing of the E60CP in the suburban Philadelphia area. Apparently the original truck had a long, "good-riding" wheelbase -- I think he said 19' but someone would have to fact-check that. They got the engine up to some amazing high speed... at which point the lead truck derailed, turned perfectly crosswise, and the engine proceeded to try to bury herself with a bone in her teeth... DIVE! DIVE! DIVE! was the expression he used while I was laughing. Supposedly the production locomotives were quickly and somewhat quietly retrucked...
I doubt water slosh was involved with the running dynamics of the ATSF cowl units, but someone more familiar with them would have to say something more definitive. Certainly even though the E60CP had a (fairly large) heating-boiler water capacity that wasn't a named or even particularly likely cause of the incident.
bogie_engineerAs I recall, there were no [SDP40F] derailments on the Santa Fe which ran them faster than anyone.
But years before, SFe did have some sort of trouble with U28CGs and/or U30CGs. Wonder if that had anything to do with water -- didn't DOT run its U30C at 120 mph on SFe around 1974?
(Found the report -- Trains 4/74 p12 says in Oct 1973 DOT's U30C did 122 mph with four cars west of La Junta.)
Erik_Mag I remember comments from the late 1970's that the derailments typically happened on roads that were know for scrimping on track maintenance.
I remember comments from the late 1970's that the derailments typically happened on roads that were know for scrimping on track maintenance.
As I recall, there were no derailments on the Santa Fe which ran them faster than anyone.
We had a baggage car in our engineering "East room" where we did buff tests and dynamic characterization testing using MTS actuators to excite the modal responses. I know there was suspicion that dynamic interaction between the lightweight adjacent baggage car and SDP40F contributed to the derailments. I know we found several maintenance issues with the trucks on the baggage car but don't believe a link was proven with the derailments. At the time of the derailments, I was the noise control engineer and had no direct involvement with the derailment work but was an interested bystander.
As I remember the dominant 'theory' in the 1970s, the "cause" was interaction between the high CG of the slosh action in the tanks and the lateral characteristics of the truck secondary suspension. Probably a resonance effect at some 'critical speed'.
"Baffles" in the tank wouldn't help much; the lateral free-surface area and hence achievable 'fetch' across the tank, which are the things that would matter in the alleged derailment forces, are not very great in the tank as configured, and it wouldn't be likely that this would be seen as an immediate cause.
bogie_engineer I know a lot of smart people at EMD, FRA, and AAR spent several years doing analysis and testing to determine the cause of the derailments and to my knowledge they never developed a proven theory.
I know a lot of smart people at EMD, FRA, and AAR spent several years doing analysis and testing to determine the cause of the derailments and to my knowledge they never developed a proven theory.
azrail Why didn't they put baffles in the water tanks..as is done with large fuel tanks? And the Amtrak SDPs were based on the Santa Fe FP45s, weren't they?
Why didn't they put baffles in the water tanks..as is done with large fuel tanks? And the Amtrak SDPs were based on the Santa Fe FP45s, weren't they?
Is there documentation to confirm there were no baffles in the water tank?
Where is the FRA/AAR report that confirms water sloshing was the cause of the derailments?
GoatBuddySomething must have gone wrong in EMD's corporate culture (which was a General Motors subsidiary), because they went from the world's biggest locomtive makers to "me-too", left behind by GE
I can add something to this since I was working in support of GM Executives 1991. They wanted to sell EMD as early as I started working there 1991. Then BN stepped forward with a big locomotive order for hauling coal primarily and GM decided to keep EMD around for a while longer for the skim. Prior to my arrival in 1991, EMD knew GM wanted to sell them for cash though. I remember an EMD guy giving one of the people I worked with a small stack of builder photos to pass onto me because he was told I liked trains. I never kept them because they were run of the mill freight diesels and still are (no real interest here). Color photo of the BN unit though........they were very happy at that large order to prove their worth to the GM HQ. It is what saved them from being sold in 1991-1992. GM viewed all ancillary business outside of car manufacture as cash cows and would skim from them to support car manufacture. Never once heard of GM HQ investing any real money in non-car manufacture business to keep them going or for that matter never saw any real cost vs benefit analysis done at HQ before the decisions to sell or retain ancillary businesses (my guess is that was mostly seat of the pants decisions).
That was a lot bigger GM back then with EMD in the family of GM Companies. After all the years of self liquidation and down sizing, predictably GM went bankrupt in 2008 and will probably do so again in the future. You could see GM was headed for serious trouble in 1991 and most of the staff in HQ knew it. Took 17-18 years to get there though with all the asset sales and cost cutting GM did piece meal.
edbentonActually everyone is missing the reason of the demise of the SDP40F the reson they had trouble holding the rail was simple. They were designed like everything else owned by the goverment by commitee. EMD said look we know what we are doing when it comes to the design of this style of engine putting the water tank in the body is a bad idea. The water tank of the SDP40F was 2000 gallons and was mounted ahead of the boilers. I am sorry but once you get that tank half empty you are going to get 8000 lbs of slosh force hitting the sides. How are the engines supposed to stay on teh rails when 8K is hitting the sides.
Hey, slow down with all typical government hate stuff! Amtrak is a corporation like any other, and believe it or not, I have seen "committee-think" blossom and doing its worst in private corporations! But "committee-think" was not an Amtrak problem for the SDP40F. They went to GM's Electro Motive Division, and asked for a strong long haul locomotive. THIS is where committee think came in, as EMD, a private corporation, decided a sloppily modified freight locomotive would do the trick!
Next: The SDP40F was needed for long distance travel, with the F40PH designated for short hauls, so the SDP40F hang-belly fuel tanks had to be max capacity. Since there was no immediate budget to replace the handed down passenger car fleet steam heaters or get new cars, heating by steam was also needed. The only place to put the water-tanks was hence in the body. This was simply bad engineering by EMD, because they could have and should have built compartmentalised tanks with multiple cells, as had been long standing practice with aeroplanes, and even before that with steam engines, which was at the time 150 year old known technology! Railroads in USA are run by business people, not engineers, so they relied on EMD to deliver a locomotive that would stay on the tracks.
EMD, a gloriously private corporation, NOT government, bungled it, end of story.
In the end, the SDP40F did serve for well over a decade, and there are oodles of images with them being lead by F40PH for headend power, so running full speed without any need to fill the troublesome tanks. These runs with one or two SDP40F coupled to an F40PH were known as fast haulers, and the SDP4F had a reputation as a fast haul-a** machine!
BTW, not all the water was in the body, as the hangbelly tanks were split between diesel and water! The belly had 2,150 US gallons (8,138.6 L; 1,790.2 imp gal) of water! The upper tanks had a capacity of 1,350-US-gallons (5,110.3 L; 1,124.1 imp gal), which still makes for over 5 tons of a liquid in a badly designed tank, free to slosh around. As already mentioned, this had long been solved for aeroplanes, otherwise they'd be dropping out of the sky like bricks, with the wing-tanks getting out whack and sloshing a few tons of fuel left or right, for a catastrophic ballast shift nobody and nothing can compensate! Even before aeroplanes, water tanks of steam engines, a 150 year old technology at the time, were baffled to control waterflow and keep it from sloshing around. There was zero excuse for the tank design failure!
Nope, it was simple engineering and quality control incompetence, not "government", which caused this failure. Something must have gone wrong in EMD's corporate culture (which was a General Motors subsidiary), because they went from the world's biggest locomtive makers to "me-too", left behind by GE. It was likely the same systemic rot, that affected Detroit's cars and trucks so very badly from the late 60s on and most definitely in the 70s and 80s!
Ever own or knew somebody with a 70s GM car? They opened the door wide for imports, and once customers saw Japanese cars, they bought them, instead of Detroit cars. EMD was a Detroit subsidiary, a private GM company!
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
QUOTE: Originally posted by chad thomas The ones that were traded to the Santa Fe did fine in freight service. They also did well as Amtrak units on Santa Fe rails. But on rough trak the water sloshing around seems to be the cause.
QUOTE: Originally posted by nanaimo73 QUOTE: Originally posted by jdirelan Also, the last couple cowl GM models (with the expection of F40) had pretty had track records. CPs problems with the SD40-2F were with the 16-645E3M, not with the Cowl carbody. CN has not had any problems with their SD50F or SD60F that I have heard of.
QUOTE: Originally posted by jdirelan Also, the last couple cowl GM models (with the expection of F40) had pretty had track records.
QUOTE: Originally posted by BNSF4ever I'm not an expert but my understanding was that cowl units like the F45 were built to safely provide crew access to internal components in bad weather. That said, no new cowl units are produced. Are they no longer necessary with widecabs or modern electronics?
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