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!

MUing

2307 views
31 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January, 2003
  • From: Ridgeville,South Carolina
  • 1,118 posts
MUing
Posted by willy6 on Sunday, October 01, 2017 2:48 PM

In the real world, if you got 2 SD70's, a SD40, a GP38 and a SD9 and the railroad has to MU them, would there be a certain order they would line these locomotives up to MU all of them?

trains
  • Member since
    April, 2001
  • From: Roanoke, VA
  • 1,502 posts
Posted by BigJim on Sunday, October 01, 2017 3:02 PM

No.
It's as simple as that.

.

  • Member since
    September, 2003
  • From: Omaha, NE
  • 8,933 posts
Posted by dehusman on Sunday, October 01, 2017 3:38 PM

No, except that the SD70 would probably be a leader if it was turned properly.  It probably has air conditioning, is the newest unit, probably has the best ride quality and seats, it might have a more crash resistant cab and have the latest technology (cameras, diagnostics, PTC, etc).

Dave H. Painted side goes up.

  • Member since
    September, 2014
  • From: 10,578’ (3,224 m)
  • 684 posts
Posted by jjdamnit on Sunday, October 01, 2017 3:58 PM

Hello all,

A caveat would be if any of these locos had been converted to a "B" unit. Not an uncommon practice with older motive power.

Then the "B" unit could not be used as a lead unit.

All being equal...then it would be how the units were arranged on the tracks.

If the locos are from different roads then the home road unit(s) would lead.

Given the "generations" and power of the different locomotive you listed this arrangement probably wouldn't be MUed...

  • SD70- -4,000 hp
  • SD40- -3,000 hp
  • GP38- -2,000 hp
  • SD9- -1,750 hp

The power of all the units would have to be "matched" to the lowest- -1,750 hp unit; thus resulting in a total output of 8,750 hp not the 14,750 hp mathematically possible.

A better solution would be to MU four SD70's or five SD40's to get the max hp. 

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

  • Member since
    September, 2003
  • From: Omaha, NE
  • 8,933 posts
Posted by dehusman on Sunday, October 01, 2017 4:27 PM

The power of all the units would have to be "matched" to the lowest- -1,750 hp unit; thus resulting in a total output of 8,750 hp not the 14,750 hp mathematically possible.

On the prototype railroads I worked on the horsepower was additive, so it would have had 14750 hp, there were other measures that derated the smaller engines, but they were all still rated for the sum of the ratings (total powered axles = TPA, dynamic brake axles = DBA).  The only place the lowest common denominator would have been used was the maximum amperage rating for how many amps for how long, where the SD9 would be the weak sister.

Dave H. Painted side goes up.

  • Member since
    November, 2006
  • From: Northeast
  • 608 posts
Posted by GraniteRailroader on Sunday, October 01, 2017 4:36 PM

jjdamnit

If the locos are from different roads then the home road unit(s) would lead.

The power of all the units would have to be "matched" to the lowest- -1,750 hp unit; thus resulting in a total output of 8,750 hp not the 14,750

The bean counters don't care what leads, home or foreign, as long as the unit us properly equipped as a leader for that territory. It's not uncommon to see foreign power as a leader.

The HP rating of the locomotives doesn't limit what gets MUed necessarily. With such a mix of power you'd be dealing with different wheel slip systems, amperage ratings, a potential mix of A.C. vs D.C. traction motors - which isn't a big deal but when choosing the leader it can matter. 

I've had GP38s MU'D to GP40s with a couple six axles in the mix. Just like when we ran a GP9 and a GP40 together because it had enough power to haul what we needed. 

(Previous) 1:1 Scale railroader - N Scale Modeler

  • Member since
    October, 2001
  • From: OH
  • 15,887 posts
Posted by BRAKIE on Sunday, October 01, 2017 7:08 PM

dehusman

No, except that the SD70 would probably be a leader if it was turned properly.  It probably has air conditioning, is the newest unit, probably has the best ride quality and seats, it might have a more crash resistant cab and have the latest technology (cameras, diagnostics, PTC, etc).

 

It would be hard for a old railroader to pass up the ride of a SD9..They didn't call those engines Cadillacs for nothing.

The only SD unit that come close to the ride of the SD9 is the SD40/40-2.

Larry

SSRy

Conductor

  • Member since
    February, 2008
  • 5,785 posts
Posted by maxman on Sunday, October 01, 2017 7:47 PM

I thought that there was a requirement that if dynamic braking was to be used, then a dynamic brake equipped unit had to be in the lead.

  • Member since
    September, 2003
  • From: California
  • 3,971 posts
Posted by DSchmitt on Sunday, October 01, 2017 10:43 PM

BigJim

No.
It's as simple as that.

 

Actually not that simple.  For instance some railroads have policys or rules that certain locomotive types will not be in the lead when MU'd with other types. .

This was often due to problems discovered in operation. Although theoretically the order should not make a difference. 

 

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

I don't have a leg to stand on.

  • Member since
    April, 2001
  • From: Roanoke, VA
  • 1,502 posts
Posted by BigJim on Monday, October 02, 2017 8:53 PM

DSchmitt
For instance some railroads have policys or rules that certain locomotive types will not be in the lead when MU'd with other types.


Not around here there weren't.
That said, and contrary to other roads SD9's, I never had an NW/NS SD9 that would MU with anything. I always had to have the darn things on the rear of the consist because of that. 

.

  • Member since
    March, 2003
  • From: Central Iowa
  • 3,912 posts
Posted by jeffhergert on Tuesday, October 03, 2017 11:45 AM

BigJim

 

 
DSchmitt
For instance some railroads have policys or rules that certain locomotive types will not be in the lead when MU'd with other types.

 


Not around here there weren't.
That said, and contrary to other roads SD9's, I never had an NW/NS SD9 that would MU with anything. I always had to have the darn things on the rear of the consist because of that. 

 

 

Maybe years ago when there was different locomotive brake equipment in service, some types couldn't lead/trail other types.  Today, just about all locomotive brake systems (at least on every class one and lease unit I've seen) are compatible so that's no longer an issue.  Here's a link to a RI Air Brake and Train Handling Rule book from 1974.  The first page shows their restrictions.  There's a chart of how to arrange the MU hoses between the different types in use then.

  http://www.rits.org/www/histories/Brakes74/PAGE1.HTM 

Jeff

  • Member since
    April, 2012
  • From: Huron, SD
  • 534 posts
Posted by Bayfield Transfer Railway on Tuesday, October 03, 2017 7:19 PM

jeffhergert

 Here's a link to a RI Air Brake and Train Handling Rule book from 1974.  The first page shows their restrictions.  There's a chart of how to arrange the MU hoses between the different types in use then.

  http://www.rits.org/www/histories/Brakes74/PAGE1.HTM 

Jeff

 

 

Loverly!  And of course there's always the "6BLC" which could (supposedly) mate with all 3 other styles and had FIVE hoses on each side of the coupler.

 

Disclaimer:  This post may contain humor, sarcasm, and/or flatulence.

Michael Mornard

Bringing the North Woods to South Dakota!

  • Member since
    September, 2003
  • From: California
  • 3,971 posts
Posted by DSchmitt on Tuesday, October 03, 2017 7:54 PM

From my faulty memory. 

The Western Pacific required GE's to be trailing units when MU'd with EMD's.

The Southern Pacific, after a major wreck, required  units from another railroad, that ofter were used on their trains, to be trailing. I believe they were the same EMD model as the SP units they ran with, but were not identical.  The SP determined there was a problem with control of the train when they were in the lead.  

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

I don't have a leg to stand on.

  • Member since
    October, 2001
  • From: OH
  • 15,887 posts
Posted by BRAKIE on Tuesday, October 03, 2017 10:26 PM

Guys,For what it may be worth I recall seeing PRR SD7/9 running solo on locals or being used as a yard engine. I don't recollect seeing them MU'd with other locomotives or each other in the Columbus area.

I checked Fallen Flags and every photo of a PRR SD7/9 was solo..

Larry

SSRy

Conductor

  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Thursday, October 05, 2017 4:16 PM

Check Chessie system/B&O SD7s and SD9s.  Mu'ed with GP40-2s and SD40 (among others).

That having been said, they did use them in yard service as well.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    November, 2015
  • 920 posts
Posted by ATSFGuy on Friday, October 06, 2017 5:13 PM

Can two Santa Fe SD75M's handle a 27/30 car spine train? No double stacks, just trinity 57' foot spine cars with 53' trailers on them.

  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Friday, October 06, 2017 6:00 PM

ATSFGuy

Can two Santa Fe SD75M's handle a 27/30 car spine train? No double stacks, just trinity 57' foot spine cars with 53' trailers on them.

 

Need more info.  Are these single spines, 3 unit, or 5 unit sets. (5x30 is a lot more trailers).   Where is this hypothetical train (locomotives are rated differently over different divisions).  Is the rail wet or dry?

Are all trailer spots full?  Is each trailer loaded to maximum legal road capacity?  

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    September, 2003
  • From: Omaha, NE
  • 8,933 posts
Posted by dehusman on Friday, October 06, 2017 6:52 PM

Short answer is yes since two C44AC's can handle a 100 car loaded coal train.  Caveat is what schedule do you want to run and what grades are you operating over.

30 cars x 5 platforms per car x 40 tons per platform and loaded trailer = 6000 tons.  8600 hp/6000 tons = 1.4 hp/tt.  That's light for an expedited schedule (assuming you want to stay on schedule) and very light if there are any grades to go over.

Dave H. Painted side goes up.

  • Member since
    April, 2002
  • 31 posts
Posted by bobyar2001 on Friday, October 06, 2017 8:50 PM

Our CPR paperwork used to say "the required horsepower for this train is 12,000HP" followed by "the available horsepower for this train is 9000HP".  That never kept them from telling us to pick up 20 loaded cement cars enroute and overloading the train even more.  Eventually, someone finally saw how foolish that was, but instead of decreasing tonnage, they simply dropped the "available" and "required" horsepower from the paperwork.

  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Friday, October 06, 2017 9:09 PM

dehusman
30 cars x 5 platforms per car x 40 tons per platform and loaded trailer = 6000 tons

 

Isnt the weight of the platform a factor?  (about an extra 67000 lbs per platform) so arent we really talking about a 11,025 ton train, not a 6000ton train. 

(67000x30x5)/2000=5025tons+6000tons

so .7hp per ton?

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Friday, October 06, 2017 9:23 PM

dehusman
Short answer is yes since two C44AC's can handle a 100 car loaded coal train.

At what speed? 

I havent seen a coal drag running at 60mph.  Intermodal however.  I would say likely no if the railroad doesnt want to loose its trailer/container traffic to the road.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    July, 2010
  • 9 posts
Posted by ed375 on Sunday, October 08, 2017 11:55 PM

About 18 years ago a local grain elevator was using a SD-9 in Burlington Northern (6009) colors for switching. The elevator sits at the end of what was the track from Mattoon, Illinois to Evansville, Indiana. The I.C. (now C.N.), still, delivers the grain cars about half to two thirds of the way to the elevator, with a re-purposed caboose as head end control platform (Push out, Pull return). The elevator sits a guestimated 4 - 6 rail miles from the I.C. main line here in Mattoon.

  • Member since
    September, 2003
  • From: Omaha, NE
  • 8,933 posts
Posted by dehusman on Monday, October 09, 2017 5:06 PM

BMMECNYC
Isnt the weight of the platform a factor? (about an extra 67000 lbs per platform) so arent we really talking about a 11,025 ton train, not a 6000ton train. (67000x30x5)/2000=5025tons+6000tons so .7hp per ton?

Nobody specified a weight, nobody said the trailers were loaded, nobody said all the platforms were loaded, nobody said all the trailers were loaded to full weight capacity.  Without somebody saying what the weight of the trailers were and what eh weight of each platform was, any answer is valid.  I picked a generic number that assumed there would be some empty trailers, some trailers not loaded to full weight capacity (a trailer of styrofoam cups or light bulbs won't weigh 40 tons) and a spine car that was less than 33 tons per platform.

Pick a number you like and do the math.  For the number I picked, the math is correct.

Dave H. Painted side goes up.

  • Member since
    September, 2003
  • From: Omaha, NE
  • 8,933 posts
Posted by dehusman on Monday, October 09, 2017 5:14 PM

BMMECNYC
 

At what speed? 

I havent seen a coal drag running at 60mph.  Intermodal however.  I would say likely no if the railroad doesnt want to loose its trailer/container traffic to the road.

Nobody specified a speed, so pick one.  The question was will it "handle" it.  Yes those two engines will move the train.  Route and schedule weren't specified.  If the route was Houston to New Orleans then yes, those engines could hit 60 and maintain a higher priority schedule.  If the route is Los Angeles to Denver, then no they probably couldn't maintain a higher priority schedule.  If you want a real specific answer then it has to be real specific question.

Dave H. Painted side goes up.

  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Monday, October 09, 2017 6:36 PM

dehusman
Nobody specified a speed, so pick one.

You dont have to....Intermodals have to compete with highway traffic.  Speed is max authorized for the track in question for the train type (assuming clear signal).  

dehusman
If you want a real specific answer then it has to be real specific question.

Which was the point of my original reply, insufficient data to provide an accurate answer.

A better answer to the question would be...maybe.

Flat terrain, probably not a problem, any mountains or long grades, probably want to add another unit. 

 

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    September, 2016
  • 7 posts
Posted by Dave Phelps on Thursday, October 12, 2017 2:35 PM
The ammeter in the lead unit would show the amps just for tht unit. Since the SD9 would have the lowest continuous speed rating, keeping the train speed above the minimum continuous speed for the other units would protect the SD9. Dave Phelps
  • Member since
    November, 2015
  • 920 posts
Posted by ATSFGuy on Saturday, October 14, 2017 8:23 PM

Regarding my post about the 27/30 spine cars and 2 SD75M's it will run on the surfline, which is flat, no serious grades to worry about there. All trailers are loaded accordingly and there are only a few blank spaces.

So is my consist okay for this route?

  • Member since
    November, 2013
  • From: Ledyard, CT
  • 1,853 posts
Posted by BMMECNYC on Saturday, November 04, 2017 8:24 AM

ATSFGuy
So is my consist okay for this route?

Probably.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
  • Member since
    January, 2017
  • From: Southern Florida Gulf Coast
  • 991 posts
Posted by SeeYou190 on Saturday, November 04, 2017 9:01 AM

dehusman
picked a generic number that assumed there would be some empty trailers, some trailers not loaded to full weight capacity (a trailer of styrofoam cups or light bulbs won't weigh 40 tons)

.

Loaded trailers should never weigh 40 tons.

.

Maximum gross vehicle weight for a non-permitted tractor-trailer is 80,000 pounds, so a trailer loaded to 40 tons would be over weight as soon as you attach the tractor.

.

A trailer that heavy would require three axles, probably three load axles on the tractor, permits, and possibly pilots/escorts.

.

What is that capacity of a spine car? I do not recall seeing three axle trailer ever loaded onto one?

.

Another question about spine cars... Are the platforms long enough to deal with the variable king pin to lead axle distances possible in modern sliding tandem trailer carriages? It would be a terrible pain for the loaders as well as the delivery drivers picking up the trailers to need to adjust the sliding tandems every time the trailers are loaded or delivered.

.

Sorry to take the MU thread so far Off Topic, but my curiosity got the best of me.

.

-Kevin

.

Happily modeling the STRATTON & GILLETTE RAILROAD located in a world of plausible nonsense set in August, 1954.

  • Member since
    November, 2006
  • From: Northeast
  • 608 posts
Posted by GraniteRailroader on Saturday, November 04, 2017 5:27 PM

Loaded trailers should never Another question about spine cars... Are the platforms long enough to deal with the variable king pin to lead axle distances possible in modern sliding tandem trailer carriages? It would be a terrible pain for the loaders as well as the delivery drivers picking up the trailers to need to adjust the sliding tandems every time the trailers are loaded or delivered.

Not sure about the platform, but its relatively easy and quick to adjust the position of the tandem rears, and drivers quite often get stuck having to do so when positioning already for docks, tight spaces, etc. It's a 30 second deal for a competent driver.

 

(Previous) 1:1 Scale railroader - N Scale Modeler

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!
Popular on ModelRailroader.com
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!
ADVERTISEMENT
ADVERTISEMENT

Search the Community

ADVERTISEMENT
Find us on Facebook