Eastern Railroad Discussion > CSX, Draw-Bar Pull ??

On the Old SP and now UPRR, we had a tonnage rating for head end road engines on different grades, listed in the division timetables, in other words, “Draw-bar Pull.” On a 2.3% grade from Ilmon to Tehachapi, it was 3,700 tons, any more than that, you must have helper units in-trained. Even the track between Palmdale and Hiland (Cajon Summit) it’s a ruling 1.2% and they had a draw-bar pull of 10,000 tons. Now, with the new equipment, I’m sure the tonnages have been raised. My question is, does the CSX have any such rule on their railroad? I’m asking because, a good friend, who is an engineer out of Manchester,Georgia told me; first of this week, CSX was running a south bound train from Atlanta to Birmingham over the Lineville Subdivision. It was 9000 feet and 14,0000 tons, with four units on the point. They broke in-two in a siding called Standing Rock. Strange thing, the locomotives did not go into emergence and to make it worse, they were having major ET problems. The crew was pulled out of service, charged with “running a train while in emergence.” I have no idea how you run a train that’s in emergence. If you have 90# brake-pipe pressure, no PC alarm and bad order ET, how do you know you’re in emergency? Sounds a little crazy, BUT IMO, even more crazy is running a 14,000 ton train with no remote/DPU helper.



Edited 5 time(s). Last edit at 12/01/16 12:51 by HardYellow.

HardYellow Wrote:
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> On the Old SP and now UPRR, we had a tonnage
> rating for road engines on different grades,
> listed in the division timetables, in other words,
> “Draw-bar Pull.” On a 2.3% grade from Ilmon to
> Tehachapi, it was 3,700 tons, any more than that,
> you must have helper units in-trained. Even the
> track between Palmdale and Hiland (Cajon Summit)
> it’s a ruling 1.2% and they had a draw-bar pull
> of 10,000 tons. Now, with the new equipment, I’m
> sure the tonnages have been raised. My question
> is, does the CSX have any such rule on their
> railroad? I’m asking because, a good friend, who
> is an engineer out of Manchester,Georgia told me;
> fist of this week, CSX was running a south bound
> train from Atlanta to Birmingham over the
> Lineville Subdivision. It was 9000 feet and
> 14,0000 tons, with four units on the point. They
> broke in-two in a siding called Standing Rock.
> Strange thing, the locomotives did not go into
> emergence and to make it worse, they were having
> major ET problems. The crew was pulled out of
> service, charged with “running a train while in
> emergence.” I have no idea how you run a train
> that’s in emergence. If you have 90# brake-pipe
> pressure, no PC alarm and bad order ET, how do you
> know you’re in emergency. Sounds a little crazy,
> BUT IMO, even more crazy is running a 14,000 ton
> train with no remote/DPU helper.

​You can run a lot more than 14,000 tons with no DPU/helper, depending on grade.  Keep in mind that your average 110-car coal train weighs about 16,000 tons.  200+ car coal trains routlinely run to Newport News with only 2 ACs on the head and that's it.

​But anyways CSX has a couple of different limits on tonnage/head-end power.  Firstly, every locomotive class has a set "tonnage rating" over any given subdivision... that is, the amount of tonnage it's rated to pull over that territory.  Obviously the more challenging the grade, the lower the tonnage rating will be for any given locomotive.  So while a single ES44AH might have a tonnage rating of like 22,000 tons from Clifton Forge to Gladstone, that same ES44AH could be rated for 7500 tons from Cumberland to Brunswick (not exact numbers mind you).  Also I -believe- that if you have a single unit instead of 2 or more, the tonnage rating of any given unit is 10% lower.  So anyways, you add up the tonnage rating of your motors over the territory you'll be operating on and then compare it to the weight of your train... you get the idea.  This isn't really the crew's responsiblity it's something Yardmasters and the like handle when making up trains or pickups.  Sometimes trains may have to actually set cars out at intermediate yards en-route because the next crew both A) has a pickup to make and B) will be going over a much more challenging subdivision and the power's not good for the tonnage if you include the pickup.  This happens a lot at Acca Yard on things like the Q416 because the legs from uhh... D.C. to Brunswick and Brunswick to Cumberland are much more challenging than the territory from Rocky Mount to Richmond.  So they have to set cars out strictly so that they'll still be under tonnage after they make their pickup.

​The other thing to worry about is what's called Powered Axles.  A locomotive's Powered Axle (and Dynamic Axle) rating isn't actually determined by the number of real axles on the locomotive.  So say an SD40-2 is rated for 6 powered axles, an ES40DC is 7 powered axles, an ES44AC or CW44AH is 9 powered axles.  Dynamic Axles are similar.  I believe an SD70ACe is 10 dynamic axles, a CW60 is 11 dynamic axles, an ES44AH is uhhh... 9 dynamic axles I think.  Some of those numbers might be off a little.  Anyways, there's a limit on head-end Powered Axles and Dynamic Axles.  Up until a couple of months ago, the limit was 24 Powered Axles and... I can't remember the Dynamic number.  It's less.  However, a new bulletin came out recently changin the limit to 27 Powered Axles.  Which was pretty nice because it made it so you could run a nice, even 3 thunderbolts on the head as opposed to before where you could only run 2 thunderbolts and then a DC of some kind thrown in for good measure. There's also a Powered Axle limit for pushers, I want to say it's 12.  However sometimes you'll see exceptions.  Like in Richmond they came out with a bulletin making an exception so pushers could run 18 powered axles back when they were bound and determined that every train out of Fulton going to the A-Line would be a double barrel.



Edited 3 time(s). Last edit at 11/30/16 14:36 by Totallamer.

You're talking about locomotive ratings...I think. I'm talking about draw bar pull. The the draw bars and knuckles on the freight cars don't care what type of locomotive is pulling on them.



Edited 1 time(s). Last edit at 11/30/16 16:04 by HardYellow.

HardYellow Wrote:
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> You're talking about locomotive ratings...I think.
> I'm talking about draw bar pull. The the draw bar
> and knuckles don't care what type of locomotive is
> pulling on them.

​That's what the Powered Axle limits are about.

No, I still think we're talking about two different things. Here's a chart from a early 1980's Southern Pacific Los Angeles timetable

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HardYellow Wrote:
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> No, I still think we're talking about two
> different things. Here's a chart from a early
> 1980's Southern Pacific Los Angeles timetable

​That looks exactly like a tonnage rating chart except it doesn't specify by locomotive type.



Edited 1 time(s). Last edit at 11/30/16 16:13 by Totallamer.

Totallamer Wrote:
-------------------------------------------------------
> HardYellow Wrote:
> --------------------------------------------------
> -----
> > No, I still think we're talking about two
> > different things. Here's a chart from a early
> > 1980's Southern Pacific Los Angeles timetable
>
> ​That looks exactly like a tonnage rating chart
> except it doesn't specify by locomotive type.

Why would the locomotive matter? I'm talking about freight cars. I don't think CSX pays any attention to this as western railroads do.

HardYellow Wrote:
-------------------------------------------------------
> Totallamer Wrote:
> --------------------------------------------------
> -----
> > HardYellow Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > No, I still think we're talking about two
> > > different things. Here's a chart from a early
> > > 1980's Southern Pacific Los Angeles timetable
> >
> > ​That looks exactly like a tonnage rating
> chart
> > except it doesn't specify by locomotive type.
>
> Why would the locomotive matter? I'm talking about
> freight cars. I don't think CSX pays any attention
> to this as western railroads do.
​
​Because the locomotive determines how much tonnage that's capable of being pulled.

Totallamer Wrote:
-------------------------------------------------------
> HardYellow Wrote:
> --------------------------------------------------
> -----
> > Totallamer Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > HardYellow Wrote:
> > >
> >
> --------------------------------------------------
>
> >
> > > -----
> > > > No, I still think we're talking about two
> > > > different things. Here's a chart from a
> early
> > > > 1980's Southern Pacific Los Angeles
> timetable
> > >
> > > ​That looks exactly like a tonnage rating
> > chart
> > > except it doesn't specify by locomotive type.
> >
> > Why would the locomotive matter? I'm talking
> about
> > freight cars. I don't think CSX pays any
> attention
> > to this as western railroads do.
> ​
> ​Because the locomotive determines how much
> tonnage that's capable of being pulled.

Drawbar rating is about the strain on the knuckle, due to the gradent of the track. That's why helper units are cut in or on the rear of trains. 

The real question is coupler limits - not nessesarly drawbar pull which I believe is closer to the term(s) being used.

Generally speaking F couplers are around 9000 tons with E's much higher.

So, as a general rule of thumb for each "E" equipped car you can subtract that weight out for those F equipped cars.

Now, that's not taking into account other forces and run outs that would overcome the rating of the knuckle.

Of course adding in helpers/DP's as noted will allow more tonnage.

HardYellow Wrote:
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> Totallamer Wrote:
> --------------------------------------------------
> -----
> > HardYellow Wrote:
> >
> --------------------------------------------------
>
> > -----
> > > Totallamer Wrote:
> > >
> >
> --------------------------------------------------
>
> >
> > > -----
> > > > HardYellow Wrote:
> > > >
> > >
> >
> --------------------------------------------------
>
> >
> > >
> > > > -----
> > > > > No, I still think we're talking about two
> > > > > different things. Here's a chart from a
> > early
> > > > > 1980's Southern Pacific Los Angeles
> > timetable
> > > >
> > > > ​That looks exactly like a tonnage rating
> > > chart
> > > > except it doesn't specify by locomotive
> type.
> > >
> > > Why would the locomotive matter? I'm talking
> > about
> > > freight cars. I don't think CSX pays any
> > attention
> > > to this as western railroads do.
> > ​
> > ​Because the locomotive determines how much
> > tonnage that's capable of being pulled.
>
> Drawbar rating is about the strain on the knuckle,
> due to the gradent of the track. That's why helper
> units are cut in or on the rear of trains. 

​And the strain on the knuckle is based on the tractive effort the locomotives are putting out due to a combination of weight and grade.  Knuckles don't break from shear weight on the drawbar/tractive effort alone.  It's shock from slack action due to wheel slippage and that kind of thing.

​Anyways here's a couple of excerpts from the Air Brake & Train Handling rule book.  Keep in mind this hasn't been updated in awhile and doesn't include probably a fair number of bulletins that have modified it over time, like the one increasing the head-end Powered Axle limit from 24 to 27.  It also doesn't include the chart with Powered Axle ratings for all different locomotive types that Engineers usually keep with them.

 



Edited 1 time(s). Last edit at 11/30/16 16:38 by Totallamer.

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Since the SP ran a lot of cut in helpers the chart relates to tonnage behind the helpers as well as tonnage
behind the head end though you start looking for that magic coupler set that's basically a neutral point.
The chart had good intent but it barely applied to things like the beets which were carried in cars built by
Balboa during his exploration of Panama! The SP chart also reflected simpler times as the "hpt" was easy
to figure, you wanted 2 horse you just multiplied the maximum tonnage (which the SP usually drug around
plus 10%)  X 2 and that gave you the power assignment (at least in theory).

Out

> ​That [SP table] looks exactly like a tonnage rating chart
> except it doesn't specify by locomotive type.

The SP table says the road engine wasn't allowed to
handle more than 3700 tons up Tehachapi, even if
the road engine was ten SD45s.

In the 1970s SP set such limits on all? their
steep hills. Other RRs didn't, or at least they
didn't put it in the timetable. One exception:
BN said an 11000-ton train could go up
1.5% Crawford Hill with no rear helper,
and that was before they replaced
the two 10-deg horseshoes with 8-deg.

http://www.fobnr.org/timetables/phase2/Denver/si/DENVER-11-102879.pdf

(top left of page 29 of the PDF)



Edited 3 time(s). Last edit at 11/30/16 17:13 by timz.

Totallamer Wrote:
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> ​And the strain on the knuckle is based on the
> tractive effort the locomotives are putting out
> due to a combination of weight and grade. 
> Knuckles don't break from shear weight on the
> drawbar/tractive effort alone. 

They sure do.

> It's shock from
> slack action due to wheel slippage and that kind
> of thing.

...as well as power greater than the couplers are capable of handling. Too much power for the couplers and you can tear the train apart with gradually increasing power. The knuckles are like a fuse. They'll go berfore andy of the big iron will.

TAW

TAW Wrote:
-------------------------------------------------------
> Totallamer Wrote:
> --------------------------------------------------
> -----
>
> > ​And the strain on the knuckle is based on
> the
> > tractive effort the locomotives are putting out
> > due to a combination of weight and grade. 
> > Knuckles don't break from shear weight on the
> > drawbar/tractive effort alone. 
>
> They sure do.
>
> > It's shock from
> > slack action due to wheel slippage and that
> kind
> > of thing.
>
> ...as well as power greater than the couplers are
> capable of handling. Too much power for the
> couplers and you can tear the train apart with
> gradually increasing power. The knuckles are like
> a fuse. They'll go berfore andy of the big iron
> will.
>
> TAW
​
​The Mechanical Department guys say otherwise.

"Knuckles don't break from shear weight on the drawbar/tractive effort alone.  It's shock from slack action due to wheel slippage and that kind of thing. "


Yes and no... you can actually pull the drawbar out with too much trailing tonnage. I've done it going east on the Tehachapis. My cut in six unit helper lost two of his units. I totally sucked out a draw bar three cars behind my road power. There was zero slack.



Edited 1 time(s). Last edit at 11/30/16 17:01 by HardYellow.

I'm looking at the original post of this thread. The fellow states the "train was in emergency" but no PC trip or brake pipe to zero on the headend. also mentions that the train was having EOT problems. The other curious thing is that the train was leaving a siding and I'm wondering if it had been stopped in the siding and somebody closed an angle cock, the tailend leaked down and setup and that caused the knuckle to break. The head end never went into emergency and still figured they had continuity on the trainline until the knuckle broke. Any opinions???   Doug

Totallamer Wrote:

> ​
> ​The Mechanical Department guys say otherwise.

Really? What is their position in the Mechanical Department? That's why helpers are cut in or on the rear.

TAW

On flat track, the load on the locomotive drawbars is that of the rolling resistance of the train, which related to the friction caused by the train's weight on the axle bearings. When going up or down a grade, no matter how slight, a portion of the train's weight becomes directly added to this load because garvity is no longer acting at right angles to the train.

What the RRs do is calculate how much of the train's weight becomes addidtive for a paricular grade (using trgonometry) and translates this into a table of weights which are expressed in various ways, because most operating employees would rather not indulge in calculations which invlove the conic sections (tangents and cosines).

Edited to add:

>IMO, even more crazy is running a 14,000 ton train with no remote/DPU helper.

Heaviest train I ever had was 15,000 tons and "four big stoves" of the 1970s era with a fully occupied "shoving platform" on the rear end.



Edited 1 time(s). Last edit at 11/30/16 17:57 by EtoinShrdlu.

SP practice was to control train speed (on trains with helpers) from the head end, the helpers in Run 8
and the head end balanced out the speed. It kept the train bunched and with the helpers cut in losing a
unit in the helper set wouldn't as severe as would be if they were at the end of the train. Santa Fe
up Cajon shoved from the rear, different philosophy, shorter hill.

Out