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Is slack still necessary?

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Posted by BigJim on Friday, June 20, 2008 3:03 PM

with a few SD90's in your consist

A few!!! As in "I've got a GE in the lead and a few SD90's in the consist"? How many units are you trying to run? Those knuckles will only take so much.

will rip her in half easy.

I guess you could if you didn't take your time.
Hard for me to believe though, because I had one of those storied SD90AC and a GE Dash-9AC and they wouldn't pull a greasy string out of a cat's pitoot! As a matter of fact, the Lance Armstrong wannabe's passed me going uphill with 2000 tons less than the units were rated for!

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Posted by UPRR engineer on Friday, June 20, 2008 12:04 PM
 BigJim wrote:

 

If you're running all GE locomotives, and are going to 'release' from a service application, that will work.  If you're running EMD's, you will get scrap metal somewhere.

BS!!!

Go back to dispatching trucks.

 

No he's kinda right, if you have a heavy train stopped on a grade, with a few SD90's in your consist.... will rip her in half easy.

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Posted by BigJim on Friday, June 20, 2008 10:53 AM

If the train stalls on a hill, taking slack will do no good.  The tonnage is too much, no matter what you do.  If you stall, the only way to move up the hill is to double (triple, whatever) the hill.

Depends on why you stalled in the first place. It's not always about tonnage. Weather and rail conditions will contribute more to stalling than anything.

Some D/A MofW clown decided it would be a good idea to send a HiRail truck out to grease the rails. Didn't take long for that idea to shoot itself in the foot! Trains stalled everywhere, not to mention losing control going downhill!!! So much for Safety First!

If you're running all GE locomotives, and are going to 'release' from a service application, that will work.  If you're running EMD's, you will get scrap metal somewhere.

BS!!!

Go back to dispatching trucks.

.

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Posted by Ted Marshall on Friday, June 20, 2008 12:12 AM
 mackb4 wrote:

 Sometimes when a train "stalls out" it's simply due to the traction motors getting to hot from excessive amperage for too long of a time.

 

This is also the reason for most traction motor failures during starting when tractive effort is at its highest. Overloading for too long of a duration.

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Posted by mackb4 on Tuesday, June 10, 2008 9:25 PM

 Sometimes when a train "stalls out" it's simply due to the traction motors getting to hot from excessive amperage for too long of a time.

 I have had to set the automatic brake brake,drop the generator field switch down,center the reverser and cool the traction motors down witht the cooling fan for the traction motors.This sometimes will get you going again.

 Now starting on a grade without slack is accomplished with placing the throttle in about the 2nd or 3rd notch,releasing the independent brake (engine) then releasing the automatic (train) brake,and start pulling remembering your amperage rating.

 We do this on "draped" trains coming west out of Bluefied,WVa.

 And by the way.I've had GE's slip up on hills quicker than I have EMD's.GE's load much slower than an EMD.

 Now I've had a second unit drop out (stall or die) while doing this before in Bluefield coming west,and 'hang on sally",grap some big air quick ,because you go backwards real fast if you don't catch it Shock [:O]

 Then check the problem out and try again.

 At least in Bluefield you got the option to get a pusher Cool [8D]

Collin ,operator of the " Eastern Kentucky & Ohio R.R."

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Posted by Modelcar on Tuesday, June 10, 2008 8:07 PM

....Zardoz:

Thanks for your reply.  It sure does make sense if a train stalls on a grade, there would seem to be little chance to restart it {with the same power}, using any kind of trick.  The power didn't get any stronger than right at the point of stall.

Quentin

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Posted by Railway Man on Tuesday, June 10, 2008 4:45 PM
 zardoz wrote:

Engineers are wrong as often as anyone else.  Each of us has our areas of relative expertise.  That's why a good dispatcher will consult with an engineer if he has any questions about how to plan a meet or overtake; and a good engineer will consult with the dispatcher if there is any question as to how trains are to be blocked, prioritized, etc. 

FYI: I left railroading years ago, and am now a truck dispatcher.  I frequently ask my drivers about what would be the best way to do certain runs.  The drivers are the ones actually at the customer location; they see what is going on; they are familiar with the territory; they know what their truck can do and cannot do; that's why I ask their advice. Sometimes they will ask me why I am routing them a certain way, and I always take the time to explain why (customer priority, late shipments, etc).

Tongue-in-cheek almost never comes across in the written word, my apologies if I misled you.

I was fortunate in my dispatching days to have some hot runners and savvy conductors who helped make my job easier.  Having read hundreds of your posts, your skills and dedication to the industry can't be questioned.  I wish you were still working in railroading.

RWM

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Posted by zardoz on Tuesday, June 10, 2008 3:06 PM

 NP Red wrote:
This is a little off the subject but awhile back I read a post in which an engineer was saying that he would have the AC locomotive in notch 6 or 7 before releasing the train brakes. This was a heavy coal drag, I think.  I would love to hear some of the tricks that you engineers have used to get a train moving. I bet there are things the management doesn't aprove of, too.

If you're running all GE locomotives, and are going to 'release' from a service application, that will work.  If you're running EMD's, you will get scrap metal somewhere.

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Posted by zardoz on Tuesday, June 10, 2008 3:00 PM
 Railway Man wrote:

OK, you're the throttle man, I'm a dispatcher. Dead [xx(] I should know better than to ever argue with an engineer. 

So, if you absolutely need to take slack to get it started, how far are you going to get with that train?  Will you be able to start it again on a hill?

RWM

Engineers are wrong as often as anyone else.  Each of us has our areas of relative expertise.  That's why a good dispatcher will consult with an engineer if he has any questions about how to plan a meet or overtake; and a good engineer will consult with the dispatcher if there is any question as to how trains are to be blocked, prioritized, etc. 

FYI: I left railroading years ago, and am now a truck dispatcher.  I frequently ask my drivers about what would be the best way to do certain runs.  The drivers are the ones actually at the customer location; they see what is going on; they are familiar with the territory; they know what their truck can do and cannot do; that's why I ask their advice. Sometimes they will ask me why I am routing them a certain way, and I always take the time to explain why (customer priority, late shipments, etc).

Regarding your question, no.  Once you stall, all the slack fiddling will do nothing except create scrap metal.  The only way to proceed after a stall is to double the hill.

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Posted by zardoz on Tuesday, June 10, 2008 2:42 PM
 Railway Man wrote:

Jeff and Zardoz:

The question I think is this:  Is taking slack a regular practice necessary to start a train, as it was in steam days?  Or an exceptional and unusual practice?  I think the other posters are asking if it's still a regular practice that if not employed will result in trains not starting.

My humble apologies if I overstated the case that it never occurs -- as we know in railroading there is always, somewhere, an exception to every rule.

RWM

As far as I know, taking slack is not that necessary that often anymore, except for isolated locations that due to grade and/or curvature that will always require special operations. With the high-adhesion locomotives and all roller bearing cars, trains roll much easier these days.

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Posted by zardoz on Tuesday, June 10, 2008 2:38 PM
 Modelcar wrote:

....How does one "hold a train" on the hill under stalled conditions, and prepare it to take out the slack without it backing down the hill out of control.....?  Does the engineer set the brakes on the following consist and push back against the applied brakes to undo the slack.....?  Than what...?

If the train stalls on a hill, taking slack will do no good.  The tonnage is too much, no matter what you do.  If you stall, the only way to move up the hill is to double (triple, whatever) the hill.

However, there are locations where we would do a setout on a hill.  Sometimes the tonnage dropped off is not sufficient to permit the train to get moving again if it is a solid train (slack all stretched).  Same thing would apply if a pickup is done on a hill. 

One does a brake set sufficient to hold the train, then gently back into the train (while the train brakes are still set) bunching the slack.  Keep going until you bump into the wall (too many cars to shove).  Then release the brakes while at the same time begin working the throttle as ambitiously as you dare, getting going as fast as you can (while not going so fast that you pull something apart).  Hopefully the momentum of the cars already moving will be sufficient to get the rest of them moving.

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Posted by mackb4 on Tuesday, June 10, 2008 2:12 PM

   Sorry if I've over read some of the posts on this subject,but here's mine.

 First are we talking about the slack between the knuckes,or the slack caused by the  the cushioned drawheads ?

 There's roughly 1 car length of slack,or traveling distance in a 100 car coal train.

 Now take a 100 car cushioned drawhead boxcar and it will be more.

 But slack is necasarry for these reasons I see as working as Engineer .

 If there wasn't slack in coal trains,the tonnage would be both hard to pull and stop because there would not be an opposite resistance.

 In a time freight type car the slack prevents hard coupling and rough handling when stopping and starting a train,sorta stops those "Iotola of slackola " Engineers  Big Smile [:D]

 But I'm sure theres those people with different opinions,but there's mine .

Collin ,operator of the " Eastern Kentucky & Ohio R.R."

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Posted by NP Red on Tuesday, June 10, 2008 2:10 PM
This is a little off the subject but awhile back I read a post in which an engineer was saying that he would have the AC locomotive in notch 6 or 7 before releasing the train brakes. This was a heavy coal drag, I think.  I would love to hear some of the tricks that you engineers have used to get a train moving. I bet there are things the management doesn't aprove of, too.
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Posted by Modelcar on Tuesday, June 10, 2008 11:47 AM

....Maybe someone will come along Chad and give us an explaination of how they really can do that.....

Quentin

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Posted by Railway Man on Tuesday, June 10, 2008 11:31 AM

Jeff and Zardoz:

The question I think is this:  Is taking slack a regular practice necessary to start a train, as it was in steam days?  Or an exceptional and unusual practice?  I think the other posters are asking if it's still a regular practice that if not employed will result in trains not starting.

My humble apologies if I overstated the case that it never occurs -- as we know in railroading there is always, somewhere, an exception to every rule.

RWM

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Posted by chad thomas on Tuesday, June 10, 2008 11:04 AM
 Modelcar wrote:

....How does one "hold a train" on the hill under stalled conditions, and prepare it to take out the slack without it backing down the hill out of control.....?  Does the engineer set the brakes on the following consist and push back against the applied brakes to undo the slack.....?  Than what...?

I was wondering the same thing Q.

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Posted by Modelcar on Tuesday, June 10, 2008 10:52 AM

....How does one "hold a train" on the hill under stalled conditions, and prepare it to take out the slack without it backing down the hill out of control.....?  Does the engineer set the brakes on the following consist and push back against the applied brakes to undo the slack.....?  Than what...?

Quentin

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Posted by jeffhergert on Tuesday, June 10, 2008 9:22 AM
 Railway Man wrote:
 zardoz wrote:

 Railway Man wrote:
.  If two SD40-2s can't start the train without "taking slack," they're not likely to move it more than a few carlengths, either......It's virtually meaningless for diesel-electrics and straight-electrics........

Say WHAT?!?!?!? 

I'm sorry, sir, but I must respectfully disagree.  Utilizing the properties of slack can be very helpful in certain operational situations. 

OK, you're the throttle man, I'm a dispatcher. Dead [xx(] I should know better than to ever argue with an engineer. 

So, if you absolutely need to take slack to get it started, how far are you going to get with that train?  Will you be able to start it again on a hill?

RWM

When I was firing, my instructing engineer once started our train (2 engines, 125 cars, around 17800 tons) on a hill using slack.  We had gone about 2/3 of the way up Mt. Vernon hill in eastern Iowa when the second engine shut down for some reason.  We notified the dispatcher, who started to figure out who could shove us over the hill.  This particular day one of the main tracks was out of service for maintenance work and we were stalled in the single track.  

We were able to get the second engine running again. My instructing engineer took over and decided to try to get moving again.  He took slack and started the train, one car at a time.  We didn't set any speed records, but made it over the hill.  Had we stopped about a mile further on, we would've been on the worst part of the grade and probably not have been able to start at all.  We didn't need the shove, which was good because IIRC, we were the last eastbound for a while, and they were going to start going west thru the single track after we cleared.

Could he have started the train without slack?  Maybe, but the tractive effort would've been so high that most likely a coupler or draw bar would've given first. 

Jeff

      

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Posted by tree68 on Tuesday, June 10, 2008 8:45 AM

I can't speak for Z, but I'd opine that the laws of momentum figure in here - it's harder to get something moving than to keep it moving.  One would have to hope that you can keep the train up to a speed that will carry it over the rough spots.

As for starting it on a hill - I'd guess no.  Not if it wouldn't start on the "flats". 

This might be a case where the crew and dispatcher might have to work together to get the train over the road without hanging it up somewhere it can't be restarted.

LarryWhistling
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Posted by Railway Man on Tuesday, June 10, 2008 7:22 AM
 zardoz wrote:

 Railway Man wrote:
.  If two SD40-2s can't start the train without "taking slack," they're not likely to move it more than a few carlengths, either......It's virtually meaningless for diesel-electrics and straight-electrics........

Say WHAT?!?!?!? 

I'm sorry, sir, but I must respectfully disagree.  Utilizing the properties of slack can be very helpful in certain operational situations. 

OK, you're the throttle man, I'm a dispatcher. Dead [xx(] I should know better than to ever argue with an engineer. 

So, if you absolutely need to take slack to get it started, how far are you going to get with that train?  Will you be able to start it again on a hill?

RWM

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Posted by zardoz on Tuesday, June 10, 2008 6:46 AM

 Railway Man wrote:
.  If two SD40-2s can't start the train without "taking slack," they're not likely to move it more than a few carlengths, either......It's virtually meaningless for diesel-electrics and straight-electrics........

Say WHAT?!?!?!? 

I'm sorry, sir, but I must respectfully disagree.  Utilizing the properties of slack can be very helpful in certain operational situations. 

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Posted by Railway Man on Tuesday, June 10, 2008 12:14 AM

 Ted Marshall wrote:
As a railfan I really enjoy watching and hearing slack action, especially when it's a really long, heavy train with minimal power. Ex.: 150 car, 15,000 ton rock train powered by two SD40-2s. I can't imagine what it would be like to start that train if there weren't any slack in the couplers.

Imagine it without any banging of slack runout.  If two SD40-2s can't start the train without "taking slack," they're not likely to move it more than a few carlengths, either.  Taking slack was a steam-engine technique required by the very low starting tractive effort of the steam engine.  It's virtually meaningless for diesel-electrics and straight-electrics which exert their highest tractive effort at starting.

Slack is still necessary to pull pins.  Otherwise it has no great value.  The larger issue is that maintenance of draft gear is a significant expense, which is why we've gone to fixed drawbar or articulated cars such as five-well double-stacks, spine TOFC cars, and permanent drawbar ore jennies as much as possible.  Slack isn't that large of an issue in lading damage with proper train handling, and eliminating it is not high on the priority list.

RWM

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Posted by Ted Marshall on Monday, June 9, 2008 11:27 PM
As a railfan I really enjoy watching and hearing slack action, especially when it's a really long, heavy train with minimal power. Ex.: 150 car, 15,000 ton rock train powered by two SD40-2s. I can't imagine what it would be like to start that train if there weren't any slack in the couplers.
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Posted by Modelcar on Monday, June 9, 2008 9:47 PM

....After watching the live web cam available now on here viewing from the Netherlands.....I notice their trains consist {generally} include about 35 to 45 or so cars.  And they really fly by the web cam at speed.  I suppose a train that length would have much less slack to deal with.

Quentin

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Posted by Anonymous on Monday, June 9, 2008 9:41 PM
Today's automatic coupler is built into the culture.    When you begin to change anything about the cars, they must still be compatible with the cars than have not yet been changed. 
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Posted by TH&B on Monday, June 9, 2008 9:11 PM

NO. Slack is not necessary technologicaly, it is built into railroad culture.

 With distributed power and unit trains and further modifications it shouldn't exist.   Look around to see what the rest of the world has of couplings.   Not all systems have slack.  Not all trains need to be so heavy.      Some comodities could be shipped by rail if it wasn't for the crash bang service provided.  

 

Railroad history has arrived with slack built into it.

 

 

Need my car use so much gas?  No, not unless l felt like changing.                 

 

 

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Posted by Anonymous on Monday, June 9, 2008 7:25 PM
I think slack might be called a necessary evil.  I don't believe that slack was provided for the purpose of starting a train one car at a time, however, it was put to that use.  As has been mentioned, couplers require a bit of slack to allow the knuckle lock to slide into position.  The coupler parts are cast without machining, so they have a considerable dimensional tolerance.  To allow for that tolerance, and for the fact that they are not lubricated, the parts must fit rather loosely.  The accumulation of that looseness adds up to the coupler slack.  Link and pin couplers had much more slack generally because there were a lot of manufacturers making the parts, which were not exactly and not always interchangeable.  So they had more looseness to accommodate the greater variation of parts. 
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Posted by NP Red on Monday, June 9, 2008 11:04 AM

Here is an interesting link that may apply in part. It appears that the  "Association of American Railroads Cushioning and Draft Systems Committee" has very smart people to figure these thins out. (maybe) I quess I didn't realize just how many different types of coulpers there were in this world.

  http://www.railwayage.com/mar01/drawbars.html

 

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Posted by NP Red on Monday, June 9, 2008 10:32 AM

To follow up, I understand that there will always be some slop in the knuckles, but isn't the majority of slack built in the drawbar  or what ever you call it? It seems to me that a 75% reduction of slack would eliminate lots of the bad stuff and not hurt the good stuff that it provides. Am I being silly here?

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