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With regard to axle loadings…

  • A typical EMD SD40-2 diesel weighs about 420,000 pounds, carried on six axles. That’s 70,000 pounds per axle.
  • A 286,000 pound freight car (very common) on four axles yields 71,500 pounds per axle.
  • A 315,000 pound freight car on four axles (not common, but legal) yields 78,500 pounds per axle.
  • NKP 765 averages about 64,000 pounds per driving axle.
  • N&W 611 averages about 72,000 pounds per driving axle.
  • UP “Big Boy” 4014 averages 67,500 pounds per driving axle.

Steam locomotives were no harder on the rails than modern diesels. They actually presented lighter axle loads than most modern freight cars.

@Rich Melvin posted:

With regard to axle loadings........

Steam locomotives were no harder on the rails than modern diesels. They actually presented lighter axle loads than most modern freight cars.

With due respect,  this seems like a significant over simplification.  Steam locomotives also have the reciprocating mass of the drive rods and connecting rods that is simply not part of diesel electric traction. I remember reading during the Ace 3000 research trials with the 614, the local track crews found the 614 put a higher pounding load on the rails than their equipment was even calibrated to measure.

Wasn't one of the many selling points of diesels over steam that diesels were much less punishing on the right of way?

I understand this isn't specific to OP's question about double headed steam power.  But if I am mistaken on this please explain it to me.   

@jhz563 posted:

With due respect,  this seems like a significant over simplification.  Steam locomotives also have the reciprocating mass of the drive rods and connecting rods that is simply not part of diesel electric traction.

Yes, it is a bit over-simplified because we’re communicating with regular folks here not railway/locomotive design engineers. A properly balanced steam locomotive did not “pound the rails” like so many seem to believe. There was some dynamic augment to contend with, but overall they did not “pound” the track.

Remember, in the steam era there was no such thing as welded rail, and most main lines were laid with 100 to 110 pound rail. Today, main lines are at least 132 pound rail, with 141 and 155 pound rail being very common. That is much heavier rail than what was used in the steam era.

I remember reading during the Ace 3000 research trials with the 614, the local track crews found the 614 put a higher pounding load on the rails than their equipment was even calibrated to measure.

I did a lot of work with those guys on the 614 ACE tests. This is the first I’ve ever heard this. Not sure that I believe it.

Wasn't one of the many selling points of diesels over steam that diesels were much less punishing on the right of way?

No.

@jhz563 posted:

With due respect,  this seems like a significant over simplification.  Steam locomotives also have the reciprocating mass of the drive rods and connecting rods that is simply not part of diesel electric traction. I remember reading during the Ace 3000 research trials with the 614, the local track crews found the 614 put a higher pounding load on the rails than their equipment was even calibrated to measure.

Absolutely untrue! The people doing the data collection on the instrumented track section were very surprised to find that the 614 was actually "easier on the track" than the diesel that operated over the same section on an hourly basis.

Wasn't one of the many selling points of diesels over steam that diesels were much less punishing on the right of way?

Not really! The major "selling feature" of the EMC/EMD FT units were it was capable of "Doing twice the work at half the cost.", primarily by eliminating all the steam locomotive maintenance overhead, such as boiler washes, coaling facilities, watering facilities, and support employees such as Boiler Makers and Water Service personnel.

I understand this isn't specific to OP's question about double headed steam power.  But if I am mistaken on this please explain it to me.

Hopefully, I just did.

@Rich Melvin posted:

Thanks Rich.  The weight of the rail and jointed vs. welded is a serious difference I hadn't considered.  I think the 614 trial data was mentioned in the ultimate steam page write up on the Ace project or maybe in the way back of the Red Devil.  It's been years since I read that, but the same source had a pretty good write up on damage to 614 after going through a crossover at a high rate of speed. It seemed credible when I read it at the time.

In my short tourist rr career I got to run mu'd diesels a couple times, but certainly didn't have a chance to mate our Porter with another steamer.  I did get check out that giant Bessemer locomotive when it was still down in McKees Rocks though, what a monster!

@jhz563 posted:

…the same source had a pretty good write up on damage to 614 after going through a crossover at a high rate of speed. It seemed credible when I read it at the time.

I find this very interesting. We ran the 765 on various Class 1 railroads back in the day, and the variations in track work standards was remarkable. On both Conrail and Norfolk Southern, going through a crossover at speed was a non-event. The crossover move was smooth and almost unnoticeable.

Crossovers on CSX, and especially on the former C&O rails, was a totally different experience! They were rough as a cob! The lateral forces were also much higher, as if the initial spiral curve was not eased enough. It would not surprise me that the 614 was damaged in a high-speed crossover move on the ex-C&O. When pulling the New River Trains on the old C&O, we learned to take the crossovers at a lesser speed that what was officially allowed. If it was a 30 mph crossover, we ran it at 20 to 25 mph. We didn’t spill the drinks back in First Class at that speed.

Last edited by Rich Melvin

LOL! The side-to-side forces didn’t cause the boiler leaks. The 614 was one huge boiler leak for that entire month. That’s why they carried two auxiliary water tanks with them on those runs.

The firebox of a steam locomotive should be as dry as a bone. I looked into the 614’s firebox once just after she had been turned in Hinton on one of those runs. It looked like a tropical rain forest.

Very educational, all above....and l gained even more respect for steam, toward which l was already  strongly biased. Since the C&O, and its steam power, is my favorite eastern road, and l rode on one of those New River Gorge specials, l wonder why C&O track, still a major freight artery?,  is rougher than others?   Amtrak ran? over it, as l was at the station at White Sulphur Springs when an Amtrak train stopped, so that is not the reason others are smoother.

@Rich Melvin posted:

LOL! The side-to-side forces didn’t cause the boiler leaks. The 614 was one huge boiler leak for that entire month. That’s why they carried two auxiliary water tanks with them on those runs.

The firebox of a steam locomotive should be as dry as a bone. I looked into the 614’s firebox once just after she had been turned in Hinton on one of those runs. It looked like a tropical rain forest.

Yikes!

I certainly wasn't there, and am doing my best to remember something I read around 15 or 20 years ago!  I remember reading about tons of leaks, and the booster engine getting trashed,  but didn't realize they were dragging 2 water cars.

Too bad nothing concrete ever came out of the Ace plans.

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