Western Railroad Discussion > BNSF SDP40F's

Since BN was one of the railroads that banished the SDP40F in the late 1970's due to their alleged flaw that caused derailments, what did ATSF (if anything) do to their ex Amtrak units that allowed them to run freight without any derailments? Following the BNSF merger, they were running without any limitations system wide which seems ironic since BN had banished them at one time.

Milwaukee Wrote:
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> Since BN was one of the railroads that banished
> the SDP40F in the late 1970's due to their alleged
> flaw that caused derailments, what did ATSF (if
> anything) do to their ex Amtrak units that allowed
> them to run freight without any derailments?
> Following the BNSF merger, they were running
> without any limitations system wide which seems
> ironic since BN had banished them at one time.

Santa Fe never had trouble with SDP40F "pattern" derailments while they were running on Amtrak (that is, trailing truck of a trailing SDP40F or lead truck of first baggage car leaving the rails as the train entered a curve of 2 degrees or more at 40 mph or more) . When Santa Fe acquired 18 SDP40F's from Amtrak in 1984, they naturally dispensed with the internal water tank (which some have fingered as the culpret) and the hollow bolster HT-C trucks (which others have blamed for the derailments). Santa Fe's "SDF40-2's" never developed a history of derailment problems in freight service, so it's not too surprising that the units were given free rein under BNSF.

Amtrak took delivery of the first order of SDP-40F's in June, 1973, IIRC. The lower numbered units assigned to the Santa Fe, SP, and BN, 500-539 I believe, were used in the then Southwest Limited, Coast Starlight, and Empire Builder power pools, and the San Diegans. On Santa Fe, once they were equipped with the Automatic Train Stop pick-up shoes, they ran at 90 m.p.h. on track so authorized by timetable.

E.M.D. sent techs out to investigate the "supposed" problem(s) with the HTC trucks; meanwhile, the SP and BN imposed speed restrictions on trains powered by them. The Santa Fe stood alone in not joining other roads with these speed restrictions, or banning them outright.

The truck was utilized on almost all "Dash-2" C-C locomotives, the exception being Conrail's SD-40-2's. Their problems seemed to revolve around the "top-heavy" SDP-40F. This, amongst other factors, led to these units having about a three year lifespan.

A number of the units had major components re-utilized in the construction of F-40-PHR's, the "R" stood for "Rebuild"; these also had the number of the SDP-40F (in small numbers on the cab), that they were built from.

Hope that explains it a bit.

Bob

ATSF100WEST......Out

Two major factors have been attributed to SDP40F derailments in passenger service, mostly on marginal track, as noted above: (1) the hollow bolster HTC truck, which looked like a regular HTC but had internal differences, and (2) the internal water tank, which made the units somewhat topheavy. However, as also noted above, the pattern derailments were either caused from the trailing truck of the 2nd SDP or the lead truck of the baggage car. I'm wondering about another possibility, which I've never seen discussed anywhere else...what about the fact that these units did not have ALIGNMENT CONTROL COUPLERS??? (They had alignment control couplers added for when they were in Santa Fe freight service).

What brought this to mind was when the F40PH's were pressed into freight service on the UPRR during the Service Crisis of 1997 to 1998, and at least one freight derailment was attributed to the F40's not having alignment control couplers, and so special restrictions were placed on the F40's from that point on: they could not be the trailing unit coupled to a freight car.

Not having an alignment control coupler will tend to pull a car off the track under less than perfect track conditions. So I wonder if this might not have been as much a contributing factor as the HTC truck or the internal fuel tank? My other question would be, why SDP40F's, F40PH's, P30CH's, and the newest Genesis units are not equipped with alignment control couplers (obviously the lack of this on shorter wheelbase units has not been a derailment factor in passenger service, but I wonder if it might not have played a role in the SDP40F debacle).

Red Wrote:
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> What brought this to mind was when the F40PH's
> were pressed into freight service on the UPRR
> during the Service Crisis of 1997 to 1998, and at
> least one freight derailment was attributed to the
> F40's not having alignment control couplers, and
> so special restrictions were placed on the F40's
> from that point on: they could not be the trailing
> unit coupled to a freight car.

F40s in freight service? I never heard of this one. Has anyone got photos of this happening? Im not saying I dont beleive you, Id just like to see it. Please post the photos if you have them. Thanks - Jared Bissen

It actually did happen.

I don't have pics of them in UP service, but I do have some somewhere in NS serivce, around the same timeframe.

Back issues of Trains and Railfan showed the F-40s in freight service on UP.


TCS - . . - .

An EMD design engineer actually got rather angry with me when I told him how I heard that the trucks on the SDP's and their water tanks were the cause of the derailment. He told me that no, nothing was wrong with the locos themselves. Amtrak had a rash of baggage cars with tired and worn out trucks and there lied the problem.

It actually makes sense, how many SDP's have ever derailed in freight service like that? And some must have been in high speed freight service in those same types of curves over the years more than just a few times.

Red Wrote:
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> Not having an alignment control coupler will tend
> to pull a car off the track under less than
> perfect track conditions.

To be more accurate, the lack of alignment control will tend to PUSH a car off the track under conditions of high buff force. When a train is running normally, the couplers will be in line along the train. When the slack runs in heavily, or when a train is in heavy DB, the couplers will tend to swing away from the center line of the train, and push adjacent cars sideways in opposite directions. Alignment control couplers limit how far the couplers can swing from their center positions, and thereby limit the amount of sideways derailing force.

Think about pulling on a chain. Every link will move to a straight line. On the other hand, if you try to push on a chain. The individual links will shift side-to-side rather than staying in line.

In the case of the Amtrak derailments, there are a couple of reasons why alignmnet control was not an issue. One is that the trains were under power, so the couplers would be near their center positions. Second, the greatest risk of jackknife derailments are with four axle locomotives, because of the design of the swinghangers in the trucks. Six axle locomotives don't present as great a risk of derailment from that cause.

> So I wonder if this
> might not have been as much a contributing factor
> as the HTC truck or the internal fuel tank?

No. The water tank is also a red herring.

> My other question would be, why SDP40F's, F40PH's,
> P30CH's, and the newest Genesis units are not
> equipped with alignment control couplers

Such locomotives aren't typically in a situation where there is high buff force in the couplers, so there is little risk of derailment.

ps68 Wrote:
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> An EMD design engineer actually got rather angry
> with me when I told him how I heard that the
> trucks on the SDP's and their water tanks were the
> cause of the derailment. He told me that no,
> nothing was wrong with the locos themselves.
> Amtrak had a rash of baggage cars with tired and
> worn out trucks and there lied the problem.

EMD did eventually admit that the trucks on their locomotives could have contributed to the derailment problem. Any initial denials were simply a circle-the-wagons reaction to potential litigation. EMD wasn't solely to blame, however, since track maintenance is also part of the picture.

Derailments of trailing trucks on six axle locomotives are a symptom of dynamic wide gauge on the track, combined with tight clearances in the trucks. The risk of derailment is aggravated by high friction, higher speeds in curves, and hollow worn wheels, all of which leads to higher gauge spreading forces. The reason railroads don't have similar today is that they have learned to recognize the symptoms, and attend to weak track sooner rather than later.

The SDP40Fs were pretty much identical to the 9 FP45s purchased by ATSF in 1967, with the only differences being the 3600 hp (same as SD45) engine and the standard SD45 trucks. There were minor cosmetic differences. The FP45s (also bought by MILW) never had the derailment problem that the SDP40F experienced, and I would think the MILW units frequently operated on less than perfect track. The F45 bought by ATSF and BN were shortened FP45s without the steam generator. Kalmbach's "Contemporary Diesel Spotter's Guide devotes a full page of text (page 95( to the SDP40F problems and the similarity and differences with the F/FP45s.

Dave
n8oayscan@woh.rr.com
http://www.railfanswelcome.com

TopcoatSmith Wrote:
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> Back issues of Trains and Railfan showed the F-40s
> in freight service on UP.
>
>
> TCS - . . - .

I once saw a BN freight with a trailing Amtrak F40 on it.

I also wondered about the SDP40's derailment problems and thought that maybe the sway motion of an SDP40 exerted on the baggage car thru the couplers had any effect. We all know what happens when we, as modelers, hook up a locomotive with a long length and couple it to a shorter car and then run it through a tight curve (On a layout). Maybe this might have contributed?

Read Preston Cook's excellent article in the Jan & Feb 1991 issues of Railfan & Railroad. Everything that has been said was probably a factor to some extent but by and large these were simply too big and too heavy freight-derived locomotives to be running at passenger train speeds except if you had exceptionally good track. Santa Fe did. The others didn't.