EMD SD40 series official thread (covers all variations)

[D.Carleton]

Trains magazine has reported that retired former C&NW SD40-2 6847 has been donated to IRM. Is this the first SD40-2 to go to a museum?

[Allen Hazen]

De-turboing a 3000 hp SD40-2 (replacing turbocharger with Roots blower) gives you a unit which is essentially the equivalent of a 2000 hp SD38-2. I don't know what this does to fuel efficiency (somebody would know: fuel consumption at various notches have been published for both models), but turbochargers are traditionally high-maintenance items: I suspect the main motive is to simplify (cheapen) maintenance. ... At a guess, a turbocharged engine with an appropriate turbocharger for its rating (the turbo on a 3000 hp engine might not be what you'd want on a 2000 hp one) would be a bit more fuel efficient than a Roots blown one (turbocharger uses energy that otherwise would be lost to the atmosphere via exhaust), but maintenance and availability of components might be the breaker.

[RickRackstop]

I've always wondered what they did to convert a turbo engine to a blower engine. Beside the turbo all the pistons will have to be changed from 14.5:1 compression ratio to 16:1, the change to smaller water pumps and lube oil pumps and all the attendant piping and I forgot the injectors. The 16 cyl. blower engine had advantages over the turbo engine operating at low power levels as far as crud in the airbox which could lead to an airbox fire and a turbo overheat/overspeed. Now with all the environmental /efficiency upgrades possible with 18:1 pistons for both types and improved fuel injectors it will be safer to misuse the turbo engine at low power and the efficiency will be close to the same. The old blower engines were slightly more efficient at low power because of the higher compression ratio, lower pumping losses for oil and water and about the same for scavenging air. If you compare a SD 39 12 cylinder turbo engine with a 16 cylinder blower engine of similar power, there is the same size pumps but less friction from 4 less cylinders. That's why converting to a 8-710 looks more attractive these days.

[jz441]

Thanks guys... The idea is to use some older SD40-2's for yard switching at an intermodal terminal and yard transfers and to reduce the cost of maintenance. Currently we need 3 GP30,35, or 38's to do the job that 2 SD40's can do.

[dash7]

Sorry if this has been posted in the wrong sub section! as i posted it in the Amtrak section and thought i might have better luck here

Hi, i know this has probably been asked before, but i was just wondering if the hollow bolster mystery on the SDP40F was ever solved as i know in the late '70s the derailments of the first truck on the baggage car derailed or the last truck on the trailing unit also derailed on anything less than class 5 track or on a curve of 2 deg or in an irregularity albeit small and there was talk about a harmonic imbalance that somehow was brought about by the slightly skewed off-center rotation of the HT-CHB truck and the brotherhood of locomotive engine men had them regulated to slower speeds with the approval from the FRA ,but apart from the fact that about 30 of them were traded in for the f40phr's, did they really know what caused it to derail?
and what was the thinking behind the hollow bolster was it a weight issue?,finally were the F40c's fitted with these trucks?
cheers, Derek

[Allen Hazen]

I have read that the F40C (for METRA, Chicago) had the same trucks and underframe as the standard SD40-2. I'm afraid I read it in (some edition of) the Kalmbach "Diesel Spotter's Guide" series, which is not an absolutely reliable information source, but for what it's worth... Certainly the F40C had the same frame lenght as the SD40-2: no need for space at the back for a steam generator.

[dash7]

Thanks for that Allen, its interesting that the F40c's haven't suffered the same fate perhaps Amtrak didn't have time to try and eliminate the problem or the resources. cheers, Derek

[Allen Hazen]

The last I hear-- after the SDP40F had been retired from Amtrak service-- was that nobody was sure WHAT the problem had been. With the units out of passenger service (and with Santa Fe, the one railroad which bought them second-hand for freight, never having imposed speed restrictions on them (being confident of the quality of their track)), probably interest in investigating the problem died down. If the problem WAS something specific to the SDP40F design, then it probably wouldn't have affected the F40C, whose geometry and weight were more like a standard freight SD40-2.
---
When the SDP40F was ordered, some influential people probably thought (and, in the anti-passenger-rail government of the day, hoped) that Amtrak would soon fold, so buying a locomotive that was basically a drag freight unit and could be resold for that service made sense. Think about it: start with a six-axle freight unit generally thought ideal for coal trains, now add weight AND length for a steam generator compartment and water tankage, then operate at passenger train speeds on a national network which, in the 1970s, was starved for investment and in many regions scrimping on track maintenance. Whether or not there was something about the SDP40F design that made it particularly susceptible to derailments, the recipe doesn't inspire confidence!

[dash7]

Thanks Allen,
I guess money losers like passenger railroad operators, especially Amtrak thought they would cut their losses by ordering a locomotive that could be easily palmed off to a freight railroad even though their funds were limited they still had a lot more money and patience to work out the bugs in this particular model than Amtrak and either way Amtrak wins ......sort of anyway.. Ahhhh.... its all starting to make sense to me now after 33 years!!!.Again thanks Allan,cheers ,Derek.

[FCP503]

Only have a moment to post, but...

I beleive that a requirement was imposed on the SDP40F acquisition process that stated that the locomotive purchased had to be based on a "stock" design. This in part accounts for the goofy nomentclature. A very common SD 40 with steam heat for passenger service good, a fully customized FP40-2 bad. This alone should imply that a lot of behind the scenes political interferance was part of the purchasing process. (when isn't it!!)

I also tend to believe that the derailment in question revealed a huge flaw in the whole Amtrak concept. Which was that the goverment could operate their money losing passener service on the existing rail network, without having to spend vast sums of money to upgrade the track that they were operating on. The truth was that there were quite a number Amtrak derailments back then caused by worn out track. If the SDP40F proved adept at exposing track defects (by derailing) then...think like a politician...it would make (A) congress look bad for trying to design locomotives when they clearly didn't have a clue. (B) Amtrak looks bad for attempting to operate equipment that they should have known was too heavy for many of the lines they were operating on. (and didn't want to pay to upgrade that very track to fix the problem) (C) Both Amtrak and congress needed to avoid any scandel that would give those freight railroads the excuse they were looking for to boot Amtrak off the property for good. Solution: It's an EMD design fault!

Also consider the history of the other two production model based locomotive models that Amrak has purchased: the P30CH wich was, well, rubbish, and the more recent DASH 8-32BWH. I can't say how good or bad this loco is, but considering the fact that there was only one order, it cleary isn't the loco that Amtrak wanted.


...must stop writing...must wrench on locos.

[dash7]

FCP503,
thanks for the informative reply, I appreciate it, it sort of sums up the SDP as a scapegoat and the pooch which to me was a great concept of cowled GE's as a runner up.
cheers, Derek

[MEC407]

Not to change the subject too much, but aside from 20 cylinders vs. 16, what were the major differences, if any, between the SDP40F and the FP45?

[Allen Hazen]

Well, the "hollow bolster HTC truck" (I've never had a very clear idea of what this is in detail, or of what difference it would have made to the tracking of the unit, but I take it that this WAS a feature unique to the SDP40F). And Dash-2 electricals. And any other mechanical changes made to the Dash-2 line from the original 40 series.

Smaller engine probably meant more room in the carbody, so probably some rearrangement of internal equipment, but I don't know any details.

Amtrak specified two steam generators, didn't they, to improve reliability on single-unit trains?

SDP40F had no front walkway: feature shared with Milwaukee FP45 but not not with Santa Fe.

Sorry, I'm just brainstorming here, trying to think of features that might be different between the two models. It's an interesting question, and I hope others can contribute answers!

[MEC407]

Basically I was trying to figure out why the FP45 didn't have the same reputation for derailments that the SDP40F had, but I guess the weight difference alone could be a big part of it, along with the different trucks and a smaller amount of water sloshing around.

[Allen Hazen]

I wish someone could explain to me just what the difference in the trucks was!
--
Another factor that may be relevant is that the majority of FP45 were operated by the Santa Fe: one of the railroads that didn't impose speed restrictions on the SDP40F, possibly because their track was good enough to take whatever an over-long, over-heavy locomotive with on-board water tanks could dish out.