Interesting power lashup

[ajmiller]

Today I saw NS 11G run up the hill at Altoona PA with 7 units lead by an SD40-2. The other units were a GP38-2, a pair of GP15-1's, a pair of high nose GP40's one of which was smoking heavily and a slug (it was number 912, listed as an RP-E4 on the roster I have). A pair of SD40-2's were also shoving on the back.
George Neat posted a nice picture of 11G on Railpictures.net at http://www.railpictures.net/viewphoto.php?id=78315

One question I have is this: is there a reason to use slugs on road trains? I haven't seen slugs often except at the hump yard in Allentown. The slug on 11G was the second to last unit, and was between a GP15-1 and a GP40. The train appeared to be running as fast as any other freight I've seen on that part of the line.

NS 11G was a very long mixed freight. Some other pictures of 11G on Railpictures.net also show a slug in the power lashup. I don't know anything else about this particular train. There must be some reason why they use them on this particular train.

[Anonymous]

Slugs are sometimes used on road trains to save on fuel costs. They use the extra power from the mother unit to power the slug, therefore It's one less engine eatingi up fuel.CSX uses them also, I've seen two csx slugs this summer one on a mow train(hauling mow equipment to another worksite) and one on a local a few days ago. CSX slugs are ussually harder to spot because they look stock from the outside. Mark Hemphill can probably shed somemore light for you
Andrew

[mvlandsw]

Slugs can produce more tractive effort at low speeds by using excess power from the mother unit. This is useful on hills where the speed is too low for the mother to operate at its full horsepower. On CSX many of the slugs seen on road trains are being transferred from a shop to the location of their use. They are frequently used on locals that need more tractive effort but not more speed. Local crews that turn back to their original terminal like them because they have a cab facing in both directions.

[csxengineer98]

what kind of slug are we talking about.... a yard slug or a road slug...
csx engineer

[ajmiller]

I didn't know there was such a thing as a road slug. This one had no cabs on it. It looked just like slugs I've seen a yard. The slug is listed as a RP-E4. After searching around on google, I found that the E means it was rebuilt from an EMD, and 4 means 4 axles, and if there was a Y in the designation, then that means it's a yard/hump slug. I guess since there's no Y, this must be a road slug.

I don't live near any CSX lines, so until today, I didn't know that CSX had slugs that looked like powered engines. That's very interesting. Can slugs draw power from multiple engines? Do they limit the maximum speed a train can run?

[Anonymous]

There's a big difference between yard and road slugs, I do believe that yard slugs pretty much become usless at anything over 15 MPH, whereas road slugs really are just locomotives without cabs.

[Overmod]

There's no real point in a slug drawing power from more than one 'mother' in a given consist, as you'd then have to deal with much more extensive wiring and control issues (such as how you avoid load seesawing from one motored unit to another) that just aren't there for a single attachment -- not to mention that the only economy advantage of a slug is when road speed is too low to utilize all the kW of generated power effectively in the locomotive's traction motors -- most locomotives run out of either engine shp or hit maximum motor rpm before the high-speed capacity of the additional traction motors becomes significant, and one generator will usually do nicely for four extra motors at usual speeds. (Imho)

Yard slugs can be much more heavily ballasted than road slugs, as things like bridge loadings are not of concern, but max TE and min wheelslip at hump or flat-switch speeds (probably no more than a few mph depending on railroad) is. A proper road slug has to match the dynamic suspension characteristics of the units it runs with -- in addition to the speed characteristics of the traction motors, etc. -- in order to be fully useful. In addition, many of the road slugs retain a control cab -- facing "out" from the paired consist -- which gets around most of the problems involved with running long-hood-forward in many situations.

Technically, there's no 'maximum speed' a road slug could reach that's different from the original locomotive it was converted from -- or from the slug mother it's attached to. There is no reason why the 'chassis' needs to be different when the engine is removed, long hood cut down, etc.

On the other hand, a slug CAN limit the top speed of a train in a different sense -- there will be an upper limit to attainable speed dependent on the peak hp/kW produced by the engine, and even if the slug is completely cut out at that point, it still represents additional train resistance without contributing additional prime-mover power. But I think the former sense is what you meant.

[ajmiller]

QUOTE: Originally posted by Overmod

Technically, there's no 'maximum speed' a road slug could reach that's different from the original locomotive it was converted from -- or from the slug mother it's attached to. There is no reason why the 'chassis' needs to be different when the engine is removed, long hood cut down, etc.

On the other hand, a slug CAN limit the top speed of a train in a different sense -- there will be an upper limit to attainable speed dependent on the peak hp/kW produced by the engine, and even if the slug is completely cut out at that point, it still represents additional train resistance without contributing additional prime-mover power. But I think the former sense is what you meant.

These are kinds of things I was thinking about. I had read on some other sites that two engines could have the same TE, but different HP, and that they could both haul the same load on the same grade, but the one with higher HP could go faster. It makes sense to me that the traction motors on a slug could be every bit as good as those on powered units, but since it doesn't contribute any HP it might limit the speed.

This particular train appeared to go up the grade from Altoona to Cresson about as fast as any other I've seen. This is probably a bad comparison, since most long freights probably don't run anywhere near their top speed going up hill.

[Nora]

QUOTE: Originally posted by ajmiller

Today I saw NS 11G run up the hill at Altoona PA with 7 units lead by an SD40-2. The other units were a GP38-2, a pair of GP15-1's, a pair of high nose GP40's one of which was smoking heavily and a slug (it was number 912, listed as an RP-E4 on the roster I have). A pair of SD40-2's were also shoving on the back.
George Neat posted a nice picture of 11G on Railpictures.net at http://www.railpictures.net/viewphoto.php?id=78315

I saw most of this bunch sitting in Conway yard this morning or last night or sometime...the weekend is all blurring together. Hehehe. I live just north of Conway and occasionally I see trains go by here with slugs too. But I have no idea why either...

[Junctionfan]

I keep seeing Union Pacific engines usually SD70Ms on NS 328 (St.Thomas, Ontario to Buffalo). That train also sees CSX, BNSF and even KCS power on it.

[csxengineer98]

a road slug is uses..well in road service...and its nothing but a loco carbody with all the guts takein out..now a yard slug is the low carbody and no cab... the pic you showed..im betting becouse it happens on csx too...is that the slug in the pic is in its way too or from a repair location...or on its way from a repair location to the yard where it will go into service agin.... odds are that that slug is dead in toe...
keep in mind that just becouse its in a "lashup" that the unit might not be online...
csx engineer

[railman]

Hey, speaking of odd lashups, coming through Elk River a couple days ago, here comes EMD 's finest. Yep, coming down the line is a couple of BNSF SD70's...followed by an ancient high hood SD-9...followed by a MRL SD40.... Where's the camera when you need it?

[fuzzybroken]

Yeah, I caught an interesting lashup here in Milwaukee a few days ago... AC4400CW-SD9043MAC-AC4400CW-MP15AC-SD60, eastbound. It stopped on Wash 4 while another train slowed to a stop headed westbound, and a few minutes later a one-unit wonder (AC4400CW) came between 'em westbound. Got a picture of the three-way meet on my website home page.

-Mark
http://www.geocities.com/fuzzybroken

[miniwyo]

Does UP use slugs??

[dharmon]

QUOTE: Originally posted by miniwyo

Does UP use slugs??

Yes, but I think they refer to them as middle management [;)]

[miniwyo]

iddle management, as in like distributed power in the middle of the train??

[miniwyo]

OH WAIT !!! nevermind i got it middle managemnt in the company. Im reatrded sometimes, seriously.

[ericsp]

Southern Pacific's road slugs looked like yard slugs. They called them Tractive Effort Booster Units (TEBU).

UP does use slugs. Scroll down to the bottom of the linked page. http://www.uprr.com/aboutup/locorost2003.shtml

[wcfan4ever]

Why did a lot of slugs disappear? I know BN had a ton of them and they all were sold off. What was wrong with them and what was there high points?

[Anonymous]

Never have seen an RP-E4D, the only slugs that run on the ex-Conrail lines are assigned for hump duty (sometimes these will be sent on the main for a 92 day inspection, I've seen the Allentown hump sets being transfered to and from Enola).

[Anonymous]

In forty some years of railroading, there are certain word usages and terms used by railfans that railroaders could always identify.

One of these is "lashup". If I ever heard a railroader use the term, I can't remember it. Railroaders refer to these as "consists".

I think "lashup" became popular in the early years of EXTRA 2200 SOUTH, and Dave Ingles of TRAINS loves the term. Fans must have picked up the term to appear "hip". It's sorta like the media like to refer to pistols as handguns, but even rifles and assault weapons fit the term. But you never hear media references to pistols, any more, and it's a shame.

But that's the way we Old Timers are . . .

[bnsfkline]

greeeeaaaat, now we have two andrew millers on the forum...Jim is confused

[TH&B]

Slug units come in all kinds of shapes and sizes. Someone here said that slugs only have one mother but slugs can have 2 mothers for one slug. I think the SBD lines had GE versions now gone and BCR seems to use them still. They look like yard slugs (low cut, no cab) but are road slugs. Other times you will see 2 slugs for one mother like on NS (all 6 axle units). I saw a CPR slug by surprise when a GP9 had no prime mover. CN has over 100 slugs in use today. Various operating conditions can make the slug a better solution sometimes other than not.

BCR has lines where 6axle power is restricted yet they run heavy trains with grades, here 4 axle road slugs can save fuel.

[ajmiller]

I thought this thread was dead and buried.

Jim,
I'm not confused. I know who I am.

[ajmiller]

Who's the other one?

[dwil89]

I would say that its a strong likelihood that the slug on that NS Train was dead in tow....heading between Enola and Conway perhaps....I have witnessed SW-1500 switchers, MP15's and SD38's many times on trains through there. These engines are almost always off-line and/or shutdown in these situations. Just a power move between Classification Yards. Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown

[dwil89]

CSX uses slugs...they also have converted locomotives to slugs without cutting the top half of the carbody. I have witnessed on a couple of recent occasions, a CSX GP30 slug coupled to a GP40. CSX has a line that branches off the Sandpatch Grade at Rockwood, Pa that runs north to Johnstown where CSX has a small yard. The GP30 slug has all roof fans removed, except for the dynamic brakes, and has radiator grilles plated over. Cab is intact, so crew can operate from the slug in one direction, and the GP40 in the other direction when returning south. Dave Williams http://groups.yahoo.com/group/nsaltoonajohnstown

[Anonymous]

Ajmiller-I'm the other Andrew Miller. Sorry for the late replay. Just happened back on it
Andrew Miller