Like the subject says, was the F40 or the AEM-7 more important in the development of Amtrak?
Neither & Both.
Locomotives are required to do business - nothing more and nothing less.
Never too old to have a happy childhood!
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My guess is had Amtrak not bought the 4-axle F40 and continued using the 6-axle SDP40F, the GE P40/42 Genesis that would replace them in the 1990s would have been 6-axle as well.
Lyon_Wonder My guess is had Amtrak not bought the 4-axle F40 and continued using the 6-axle SDP40F, the GE P40/42 Genesis that would replace them in the 1990s would have been 6-axle as well.
The F40PH first entered the roster as a complement to the six axle model. Only after its success were SDP40F rebuild plans discontinued and trade-ins on more F40's decided upon.
So the F40PH, while not dominant on Amtrak's roster had the 150 SD's handling long distance trains stuck around, still may have influenced the decision to go 4 axle when it came time to acquire a new generation of power. There would've been at least 30 of them on the roster had the SD fleet remained intact, and quite possibly several dozen more when all was said and done (216 F40PH's were eventually bought new or 2nd hand by Amtrak, while there were only 150 of the six axle EMD cowls).
The demise of the SDP40F has been debated endlessly since the first derailments and it's questionable whether the actual cause has been discovered. At any rate, Amtrak's management deserves high marks for addressing this issue promptly, even if many within the hobby disagree with the decision that was made.
16-567D3A I think Amtrak was too quick to dump SDP40F,particularly after the cause of their series of 1976/77 derailments was determined after extensive testing to be half full steam generator water tank contents sloshing around in conjuntion with the hollow bolster HTC trucks.since Amtrak was already committed to full conversion to HEP.elimination of steam generator equipment and the installation of Head end power skids and if necessary truck replacement with Flexicoils should have solved the yaw and pitch dynamics and harmonics that set up the SDPs rear truck and lead truck of the trailing car to derail at speed
I had to read through all the test reports from all the tests performed on the SDP40Fs after the series of derailments. The test results found nothing at all. Amtrak, however, needed to do SOMETHING, the SDP40F's image was beyond repair with the RR operating officers - particularly at Conrail.
Back to the original question... I'd say the AEM7 over the F40PH, although it's close.
There are two reasons for this:
1) The alternative. The alternative to the AEM7 was to try to keep the Metroliners going plus use GG1s, and small handful of E60s on everything else. The GG1s were truly ancient and needed quite a bit of TLC to keep them going - plus needing a generator car for HEP equipped trains. Wilmington was up to the job, but being "stuck" with what was essentially a 90 mph max on non-Metroliner trains would have really stiffled NEC growth.
Outside the NEC, the alternative would have been to rebuild E8s. Amtrak did four of them (or was it five?), plopping in a HEP skid in place of the steam generator. At least 3 of these still survive in operating condition. E8s have unique trucks, but everything else could be rebuilt and/or modernized indefinitley. Not nearly the chore of keeping GG1s going.
2.) Commercial: The NEC vs LD train "discussion" is probably the most contentious one among us railfans, but even my very conservative, red state, "Fair tax", republican congressman recognizes the value of the NEC and supports it's funding.
https://youtu.be/JOb7dNNwd4g
The success of the NEC is what drives Amtrak's value. Without the AEM7, the NEC never quite gets to a "full boil". The Metroliner saved the US passenger train and got Amtrak created. The AEM7 saved Amtrak.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
CSSHEGEWISCH The demise of the SDP40F has been debated endlessly since the first derailments and it's questionable whether the actual cause has been discovered. At any rate, Amtrak's management deserves high marks for addressing this issue promptly, even if many within the hobby disagree with the decision that was made.
+1
I would agree at the Metroliner "saved the US passenger train" in pointing to what was possible with a near high-speed corridor service in a densely populated market.
The AEM-7 is what "saved" the Metroliner inasmuch as the Metroliner was a "carbarn queen" since its introduction. That locomotive and the Amfleet cars it pulled.`
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
The AEM7 saved the NEC and Amtrak. The FP40 helped with New Haven - Boston before electrification, so it also had its part. And was essential for the NEC also. Cannot have one without the other. Although thoroughly rebuilt E-units would also have done the job. So my vote goes for the AEM7.
Similarly, thorouhgly rebult E-unites could be handling the LDs today!
I'm not sure how we got on to the topic of the tendency for SDP40F's to derail at speed, but something clearly seemed to be at play that created issues on trackage that was less than ideal where 4 axles and A1A E's were running fine. They may of been unfairly criticized and we never got any definite answers, but clearly, they weren't suited to some of the conditions they were tasked to serve on.
When the F40PH proved itself and EMD's trade-in allotment combined with the cost to overhaul the SD's while converting them to HEP (Remember how their preinstalled HEP wiring, done to Amtrak's specifications, would've been needed to redone at great expense?) made it a wash, not hard to understand why the more flexible F40PH that didn't have a poor reputation and which was more forgiving to troublesome track conditions, got the nod instead.
Leo_Ames I'm not sure how we got on to the topic of the tendency for SDP40F's to derail at speed, but something clearly seemed to be at play that created issues on trackage that was less than ideal where 4 axles and A1A E's were running fine. They may of been unfairly criticized and we never got any definite answers, but clearly, they weren't suited to some of the conditions they were tasked to serve on. When the F40PH proved itself and EMD's trade-in allotment combined with the cost to overhaul the SD's while converting them to HEP (Remember how their preinstalled HEP wiring, done to Amtrak's specifications, would've been needed to redone at great expense?) made it a wash, not hard to understand why the more flexible F40PH that didn't have a poor reputation and which was more forgiving to troublesome track conditions, got the nod instead.
You never have a 2nd chance to make a 1st impression.
For passenger rail use which is better? 4 or 6 axle?
zkr123 For passenger rail use which is better? 4 or 6 axle?
To make speed you need HP. The amount of HP in a diesel electric is limited by the HP of the diesel. In Theory, you can go faster distributing the power of the diesel into 4 traction motors than you can by distributing it into 6.
ie. 3000 HP / 4 traction motors = 750 HP per traction motor3000 HP /6 traction motors = 500 HP per traction motor.
The gearing of the traction motors will determine the actual top speed. In theory the higher HP rating will attain top speed faster.
Four axle trucks also have less impact on the track than six axle trucks, to a significant degree. NJT's U34CHs were nicknamed "curve straighteners" because of this.
But the Blount thee-axle trucks with unpowered center axle were reasonbly kind to the track and gave a very smooth ride. (E-units)
daveklepperBut the Blount thee-axle trucks with unpowered center axle were reasonbly kind to the track and gave a very smooth ride. (E-units)
I think you mean Blomberg, not Blunt.
I'd be interested to see a discussion of the relative 'track kindness' and stability of the "Blomberg" A-1-A truck vs. the long-equalizer pedestal trucks on many other contemporary passenger units (notably PAs).
(I have always wondered how a three-axle Flexicoil truck with typical '60s C-truck bolster arrangements was expected to be stable at high speed...)
For a good ride, you want soft secondaries and stiff primary suspension. Also, you want good, lateral suspension.
Another big difference as speed is the length of the locomotive and the distance between bolster centers. Longer is better.
Comparing the trucks on an E8 with those on a PA:
Both are equalized. The PA has drop equalizers, the E8 straight bars. No real difference.
The E8 has outside swing hangers, the PA, inside. Swing hangers are a good lateral suspension arrangement. Slight advantage E8.
Both used stiff coil springs for the primary, and soft leaf springs for the secondary springs. A good arrangement since the leaf springs tend to be self-damping.
I'd bet an E8 rode a bit better at speed than a PA, but mostly because of the longer length.
Steam locomotive driving wheels were universally without lateral or swing motion?
Steam was famous for rough riding, but I heard that some top-line late-era steam (AT&SF 4-8-4's?) rode well. Maybe not as well as an E-8 that Model Railroader's Jim Hediger described as a "Cadillac" when he graciously answered my questions at the Madison (Mad-City) Model Railroad Show, but smoothly enough in high-speed passenger service. He characterized PAs as rough-riding from his prior experience in the railroad industry.
Paul MilenkovicSteam locomotive driving wheels were universally without lateral or swing motion?
They had a the pilot truck to try to keep things calm laterally, so the drivers didn't have to deal with much. Not a great arrangement, but tollerable, apparently.
Paul MilenkovicMaybe not as well as an E-8
My recollection from reading SDP40F reports 30+ years ago... I was surprised at the small difference in lateral forces at speed on 2 degree curves between the SDP40F, an E8 and a Flexicoiled SD40. They came out in the order you'd expect, but there wasn't much of a gap. None were close to "dangerous".
Paul Milenkovic Steam locomotive driving wheels were universally without lateral or swing motion? As I recall, some drivers towards the center had no flanges, which allowed lateral movement. I may be absolutely misremembering, but it seems to me that some driver boxes allowed for lateral movement, also. Steam was famous for rough riding, but I heard that some top-line late-era steam (AT&SF 4-8-4's?) rode well. Maybe not as well as an E-8 that Model Railroader's Jim Hediger described as a "Cadillac" when he graciously answered my questions at the Madison (Mad-City) Model Railroad Show, but smoothly enough in high-speed passenger service. He characterized PAs as rough-riding from his prior experience in the railroad industry.
Steam locomotive driving wheels were universally without lateral or swing motion? As I recall, some drivers towards the center had no flanges, which allowed lateral movement. I may be absolutely misremembering, but it seems to me that some driver boxes allowed for lateral movement, also.
Johnny
Deggesty Paul Milenkovic Steam locomotive driving wheels were universally without lateral or swing motion? As I recall, some drivers towards the center had no flanges, which allowed lateral movement. I may be absolutely misremembering, but it seems to me that some driver boxes allowed for lateral movement, also. Steam was famous for rough riding, but I heard that some top-line late-era steam (AT&SF 4-8-4's?) rode well. Maybe not as well as an E-8 that Model Railroader's Jim Hediger described as a "Cadillac" when he graciously answered my questions at the Madison (Mad-City) Model Railroad Show, but smoothly enough in high-speed passenger service. He characterized PAs as rough-riding from his prior experience in the railroad industry.
From 1842 to 1866 Baldwin built the "flexible-beam truck" locomotives which allowed the front axle to move sideways remaining parallel to the other axles. As far as I know, this was the only steam locomotive design that had lateral motion in its drivers. The lower half of this illustration shows the position of the left wheels on a section of curved track. Note that the third set of drivers are blind--no flange. Illustration is from John H. White, Jr's "A History Of the American Locomotive --Its Development:1830-1880."
https://www.flickr.com/photos/paulofcov/16971055161/in/album-72157626021256880/lightbox/
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
"My recollection from reading SDP40F reports 30+ years ago... I was surprised at the small difference in lateral forces at speed on 2 degree curves between the SDP40F, an E8 and a Flexicoiled SD40. They came out in the order you'd expect, but there wasn't much of a gap. None were close to "dangerous"."
One difference between the HTC and the Flexicoil was the split in vertical displacement between the primary and secondary suspension.
The Flexicoil had relatively hard primary springs over the axleboxes and relatively soft flexicoils between the frame and bolster.
The HTC had almost no flexibility vertically between the truck frame and bolster but was intended to be soft laterally to allow the truck to match track conditions. But the primary springs had to be softer to compensate for this change.
If you think about an SDP40F in a sharp curve with most of the lateral travel of the secondary rubber pads already taken up, and then there is a small extra loading from water surge in the above frame tank, that might take the lateral loading above that seen in test conditions, possibly with a full tank.
The same thing could happen to an E-8 or an SD40 if it hit an irregularity and the secondary lateral travel happened to be nearly used up.
I was nearly thrown out of a vestibule with the doors open when a passenger truck hit its lateral stops in a sharp curve during high speed trials. Luckily there were plenty of handrails to grab.
M636C
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