20/20 Did anyone do the math?

1619 views
34 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Monday, March 16, 2020 8:43 AM

Yes, they did. They kept developing the Y class right up until the end. Long after other RRs had given up on the compound articulated.

.

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Sunday, March 15, 2020 9:35 PM

Thanks Big Jim, now I know.  Whether it was a common occurance or not is immaterial to me, but knowing the capability was there when needed is good enough. 

N&W built some good stuff, didn't they?

  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Sunday, March 15, 2020 8:48 PM

Flintlock76
so, just how fast  could those Y6b's go? 


As I have quoted many times before from an engineer that ran them, "67 mph was about as fast as they would go, but, you really didn't want to run them over about 63 mph as after that they got pretty shakey".

And, this from someone who rode behind one..."after finishing spraying to Hagerstown, MD on the Shenandoah Division, our entire spray outfit was attached to the rear of a night train to Roanoke.  In those days, Class Y locos were known to run 55 - 60 mph on the upper end of the Valley, and ours that night was no exception.  The unsnubbed trucks on our car took the place of a motel vibrating bed that night."

.

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Sunday, March 15, 2020 5:57 PM

For what it's worth...

My MTH Y6b will go so fast it'll fly off the train table and out the window if I let it!

Not the same thing, but just sayin'. 

Good little engines, those MTH O gauge products!

  • Member since
    September 2003
  • 13,418 posts
Posted by Overmod on Sunday, March 15, 2020 4:57 PM

The nominal 'absolute record' speed documented for a Y6 is a severe outlier, being pushed downhill into a sag by the train, with the engine one day out of the shop for a major. 

Th horsepower curves drawn for these locomotives show a radical falling-off of horsepower above 35 or so mph -- that does not indicate their 'top speed', only that the likelihood of them running fast on the level, let alone upgrade, with the train resistance that would have been assigned to get them to operate in the 'usual' speed range on that stretch of track, becomes increasingly implausible.  The great theoretical issue is the loss of effective balanced cylinder hp in the low-pressure engine at higher cyclic rpm with the valve gear set where it 'has to be', the effect being further magnified by effective loss of effective compression 'cushioning' of inertial mass 'as overbalanced' in the hinged engine.  Some of these effects could be overcome with judicious use of the 'booster valve' and I have argued that better proportional control of IP steam modulation and valve timing/duration could indeed allow one of these 2-8-8-2 chassis to work time-freight speed compound.

There s at least anecdotal evidence that N&W engineers tried to work these things fast in the frequent observation that -- net of all the great and justly-vaunted N&W maintenance, the things often sounded like accidents in a boiler factory running at any kind of speed on the road.  N&W proponents have attempted over the years to 'explain this away' by claiming that even though there was high mechanical noise, the excellent Virginia construction was showing no evidence of damage.  This is dubious from first principles alone.   However it's also no proof that good design and good maintenance weren't in fact in play.

I've said before that there are two things I'd like to be turned loose to play with: one is a Y6 chassis to be fitted with better balance and compliance and full IP modulation; the other being an A with the full Cincinnati service lightweight rods and Glaze-style balancing.  I personally have no doubt of the ability of the Y6 design to reach high speed if properly balanced and 'reheated' -- the limit being the inertial augment derived from the relatively heavy LP piston mass at given stroke expressing on the stability of the hinged forward engine.

  • Member since
    July 2016
  • 896 posts
Posted by Backshop on Sunday, March 15, 2020 1:50 PM

Just a couple of thoughts...

1. I'm a subscriber and I also found the latest issue extremely boring.  With 20 articles, they were too short to be anything but superficial.

2. A 92 car consist in Big Boy years was a lot lighter than the same number of cars in the 1970s.  In the 50's, there weren't any autoracks, high cube boxcars, Big John covered hoppers, etc.  It was mainly 40ft boxcars and smaller hoppers.

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Sunday, March 15, 2020 1:11 PM

OK Big Jim, you were there and I wasn't , so, just how fast  could those Y6b's go?  

I've had some old-timers here tell me from first-hand experience Class A's would run away from chasers driving on Route 460, and we know the Class J's could fly when given the chance, so how about the Y6b's  

  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Sunday, March 15, 2020 11:57 AM

Flintlock76
Granted, on the N&W a Y6b typically didn't go faster than 35mph.  The exception was during WW2 when they were pushed up to 50.  Wartime traffic had to move. 


Another myth!
You have been reading too many old wives tales from the people that paid no attention to what was happening on the N&W and haven't been listening to the right soundtracks! Where the curves eased and track speed limits permited, the engineers would let 'em stretch their legs...all the way until they were removed from service!

.

  • Member since
    December 2017
  • From: I've been everywhere, man
  • 2,787 posts
Posted by SD70Dude on Sunday, March 15, 2020 11:02 AM

mvlandsw

I remember reading a long time ago about throttle restrictions with high horsepower consists on the UP. With 30,000 hp the throttle was not to be advanced to the 8th position until train speed was up to 30 mph where the tractive effort is reduced.

This makes sense.  But the Engineer would still have to be very careful when starting the train with all those units online. 

Greetings from Alberta

-an Articulate Malcontent

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Saturday, March 14, 2020 12:19 PM

mvlandsw-- Thank You! Rather wonder how widespread this practice became during the 'Unlimited Horsepower' years. 

Can you imagine 6 DD35's at high speed. Holeee mackerel. 

Then again the UP always had the big stuff, Big Boys, Turbines, Big Blows, plenty of wide open running and some stiff grades. 

 

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Saturday, March 14, 2020 11:07 AM

Gee, how fast did UP want to go?  I've read a Big Boy was good for up to 70mph, at least on level ground with a typical consist.  A Challenger as well.

Granted, on the N&W a Y6b typically didn't go faster than 35mph.  The exception was during WW2 when they were pushed up to 50.  Wartime traffic had to move. 

  • Member since
    December 2001
  • 729 posts
Posted by mvlandsw on Saturday, March 14, 2020 12:51 AM

I remember reading a long time ago about throttle restrictions with high horsepower consists on the UP. With 30,000 hp the throttle was not to be advanced to the 8th position until train speed was up to 30 mph where the tractive effort is reduced.

A Big Boy could handle 92 cars but not nearly as fast as a 30,000 hp diesel consist. The reason the UP got into high HP diesels and turbines was to run fast trains over their long distances.

Mark Vinski

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Friday, March 13, 2020 11:39 AM

The photo caption says it all "UP nickname Unlimited Power"..."formidable consist"..."infatuation with giant double engined Diesels".

As stated previously I'm not generally very taken by Diesels but this lashup gets a nod. 

Even if you replicated it on a model railroad, in my case N scale, it would cause quite a rumble and stir! 

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Friday, March 13, 2020 10:52 AM

Maybe some those DD's are dirtier than others?  Maybe they've gotten a load of cheap fuel?  Wink

"Dirty Dick's Discount Diesel?" 

  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Friday, March 13, 2020 9:55 AM

That would be twelve exhaust stacks. I don't see that many plumes.

.

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Friday, March 13, 2020 9:52 AM

For those of you that denied themselves or think we are talking about helpers: 

  • Member since
    April 2018
  • 1,500 posts
Posted by Jones1945 on Friday, March 13, 2020 2:23 AM

Flintlock76

Six DD35's on a 92 car freight?  Jeez, a "Big Boy" didn't need any help with a 92 car freight!  An N&W Y6b wouldn't have needed any help either! 

You call that progress?  Wink

If the PRR Q2 was tested by the Union Pacific, the "8000hp" PRR Q2 wouldn't need any helper as well! Even though the starting T.E of Q2 was lower than the "Big Boy" (115,816 lbf with booster Vs. 135,375 lbf). The experimental PRR Q1 could easily handle a 100-car freight on level track and reach 40mph at 40% cutoff...  

  • Member since
    December 2017
  • From: I've been everywhere, man
  • 2,787 posts
Posted by SD70Dude on Thursday, March 12, 2020 2:53 PM

CN's current operating rules allow 24 powered DC axles in a consist, which may be increased to 30 on certain subdivisions with a supervisor's authorization.  With an AC unit it is 18 axles. 

Dynamic braking is restricted to 18 DC axles/consist, 12 if you have an AC unit. 

The rules on other railroads may vary.  As an example, before the Mount MacDonald Tunnel was built in the 1980s Canadian Pacific used to run 6-unit SD40 helper sets in the middle of loaded trains on Rogers Pass.  36 powered axles in that consist, but since they were pushing as much or more than they were pulling drawbar strain does not seem to have been nearly as much of a problem.

https://www.youtube.com/watch?v=kBPVTEx9Syw

The Utah Railway did the same:

https://www.youtube.com/watch?v=2Za57_HF5H8

Greetings from Alberta

-an Articulate Malcontent

  • Member since
    May 2012
  • 4,221 posts
Posted by rcdrye on Thursday, March 12, 2020 1:58 PM

CGW's "standard", at least on the line out of Chicago, was 9000 HP with 6 F-units (A-B-B-B-B-A), or four GP30s, or three SD40s.  CGW bought additional F7B's just to fill out their lashups.

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Thursday, March 12, 2020 1:50 PM

Well as previously stated they are all ejecting a very forceful straight up plume of exhaust. That would mean every engine is working. If that means they are engaged with the traction motors I don't know. 

The Chicago Great Western would run huge lashups of F units but maybe not 30,000 h. p. worth.

  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Thursday, March 12, 2020 1:26 PM

Balt,
There have bee rules in place for a very long time about how many axles may be on line in power and dynamic brake. Suffice it to say that it is not going to take long for that 30,000 HP to bust a knuckle or worse jerk a drawhead out of the end of a car.
To you railfans, all of that power makes for a good story. But, in the real world, it is most likely a lot less power on line than some of you want to "mythisize" about.

.

  • Member since
    May 2003
  • From: US
  • 19,318 posts
Posted by BaltACD on Thursday, March 12, 2020 11:22 AM

CSSHEGEWISCH
Keep in mind that it's quite possible that this was a power move and some of that power may have been offline and idling rather than sending electricity to the traction motors.

30,000 HP would work wonders with the lead drawbar.

I guess I led a sheltered railroad career - I never heard anything about limiting head end locomotive power until the AC locomotives began to appear on the property.

Of course until the sustained pulling power of the AC units showed up it was never considered that trains could be built that would exceed the capacity of high strength knuckles.

What was a BIG train 40 years ago would not be worthy of operating these days - hold it for tonnage until a 'proper train' can be accumulated.

  • Member since
    March 2016
  • From: Burbank IL (near Clearing)
  • 12,093 posts
Posted by CSSHEGEWISCH on Thursday, March 12, 2020 10:29 AM

Keep in mind that it's quite possible that this was a power move and some of that power may have been offline and idling rather than sending electricity to the traction motors.

30,000 HP would work wonders with the lead drawbar.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Thursday, March 12, 2020 10:03 AM

I'm sure the UP had a reason to put 30,000 h.p. on that train, even if it was just as a trial. 

  • Member since
    January 2019
  • From: Henrico, VA
  • 5,277 posts
Posted by Flintlock76 on Thursday, March 12, 2020 9:49 AM

Six DD35's on a 92 car freight?  Jeez, a "Big Boy" didn't need any help with a 92 car freight!  An N&W Y6b wouldn't have needed any help either! 

You call that progress?  Wink

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Thursday, March 12, 2020 9:38 AM

It's a 92 car freight. There are very distinctive individual plumes, shooting straight up, coming from every one of them. March 18, 1975.

I would say the train is just getting under way, or labouring on grade. 

  • Member since
    April 2001
  • From: Roanoke, VA
  • 1,840 posts
Posted by BigJim on Thursday, March 12, 2020 8:56 AM

Miningman
The A-B-B-B-B-A 30,000 h.p. UP DD35's running for Cajon was a real eye popper.

I doubt that all of those units were on line! Instant "scrapiron"!

.

  • Member since
    September 2013
  • 6,199 posts
Posted by Miningman on Thursday, March 12, 2020 12:55 AM

Well that's too bad... I'm sure the News Agent fellow was amused as is Classic Trains with you're comment.

At least you get to use their Forum for nothing so it doesn't cost you to dole out a put down. 

The A-B-B-B-B-A 30,000 h.p. UP DD35's running for Cajon was a real eye popper. A serious ground shaking moment I'm sure and the sound something perhaps a dedicated steam lover like myself could tip his hat to, begrudgingly mumbling something about "not bad". Only my dog here to confirm that though.

  • Member since
    January 2002
  • 4,087 posts
Posted by M636C on Thursday, March 12, 2020 12:17 AM

On the more general subject of the 20th anniversary issue, I skimmed through it and left it on the shelf at the newsagent.

By chance I had the 15th anniversary issue with Preston Cook's article on F units out, and I reread that issue. That was really something. Not quite as detailed as we got from X2200 South in Don Dover's time, but definitely a reference on the subject.

Peter

SUBSCRIBER & MEMBER LOGIN

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

FREE NEWSLETTER SIGNUP

Get the Classic Trains twice-monthly newsletter