Hood and cowl units both demonstrate a major advantage over carbody types in that the frame carries the weight and the hood or cowl can be removed to provide access and elbowroom for maintennance. Structurally, an F45 and SD45 are virtually identical, the sheetmetal is about the only real difference.
If I am not mistake, Cowl units are still being produced, I.E. MP36-3 (?) and untill just recently, the P42-9’s and F59PHI. I belive these would count as Cowl units, even though they were purchased for the sole use on Passenger trains. For frieght use, however, look at the previouis post, CP/CN/BCOL had C40-8 cowl units designated C40-8M, and CP Rail bought SD40-2F’s in 1986, making them the last units built in the SD40 Series
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 p
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?
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 di
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?
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.
Dave
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 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’.
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.
“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.
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.
Dave
FWIW, when Amtrak set the 50-mph-on-two-degree-curves limit in January 1977, SFe gave its crews a note saying the slowdown was Amtrak’s rule, not theirs. (If anyone doesn’t believe that, I might be able to find that piece of paper.)
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.)
My guess would be that it was truck guiding instability, probably in yaw complicated by hunting behavior (which is yaw coupled to roll).
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.
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 h