Eastern Railroad Discussion > CSX road slug questions.

I have seen some of the CSX road slugs in train consists, what are they used for ? Starting traction ? Breaking ? Fuel tenders ?
I have recorded the road numbers, but not until I looked them up in my roster guide did I know what they were.

Any answers will be very helpful, thank you.

Play safe.
Dan.

Non Powered slugs are set up to pull current generated by the powered engine and apply it over the traction motors of the non powered unit. This increased tractive effort is most effective at low speeds, i.e. switching or starting heavy cuts from a stop, but drops off significantly as speed is increased. CSXT's road slugs are configured with a controlling cab and are frequently paired up long term with their powered mates. Many sets are equipped for fuel transfer to the powered unit as well. The fuel acts as ballast for the non powered unit. Slugs will frequently be ballasted with concrete if, by design, not intended as a fuel tender. The connections required for the current and fuel transfer make seperation of the two units, for whatever reason, problematic in the field, hence long term pairings. I am fairly certain that most CSXT road slug pairs are equipped with dynamics, but my exposure to them is limited.

Hi Dan,
The Road Slugs on CSX are basically used for traction and braking. Most if not all of them still retain their dynamic brakes. When these were built, they also were set up to be fuel tenders for the "mother", but since then this idea has been rethought and most if not all of the slugs have had their fuel tanks capped and fuel transfer hoses removed. The new repaints even have a steel plate welded over the area of the fuel filler just to make sure their message is understood... Don't fuel the slugs.

The mother slug sets work well in low speed or local type operations as the slugs seem to cut out about the time their mother makes "transition" @ about 25 m.p.h. Then it's just the GP40-2 doing all the work.

Andy

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Often the slugs are operated as the lead unit. Crews like them because they are quiet(no diesel noise).

One thing that kinda sucks about them though, is the heaters don't always work so well in the winter. Spent many a winter night freezing my butt off as a conductor because the heaters wanted to blow out luke warm air.

Nice to see a GP30 in YN3 paint!!!

These sets are also rated as having the power of 2 GP38-2's.

KV1guy Wrote:
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> These sets are also rated as having the power of 2 GP38-2's.

Even the few pairs that have GP38-2 mothers?

I have no idea. CSX said they have the power of 2 GP38-2's...but that was before the 38 combo's started showing up.

The horsepower equivilants work like this:
Slug + GP38-2=1 GP40-2(3,000hp) with 8 traction motors instead of 4.
Slug+GP40-2=2 GP38-2's (4,000hp) with 8 traction motors equalling 8.

SO, if you have slow short heavy cuts, the slug/38 consist is good. otherwise, the slug/40 consist works best.

Personally, the slugs get a B- from this engineer. great idea for the company on jobs that need to travel both directions for longer distances, but with fewer cars than what 2 normal units would need.
They are far too cold in winter, yes they are quiet, but the horns are DEAFENING...and I'm not exaggerating here. Imagine someone blasting a K5 in your bedroom to wake you up...it's that loud. But then, CSX is too cheap to move the horns, instead paying out millions in hearing loss claims to the crews, while all the other class ones have moved the horns back mid-unit years ago...but I digress.
The slugs do indeed "drop out" at transition (25-27mph) and at that point, the ampmeter in the slug will read what the trailing unit is loading. My worst experience in this situation was a pair of slug sets (so, that's 1 slug, 2 GP40's and 1 slug) on a loaded ballast train. The train would get up to around 30, the slugs would drop out, and the speed would drop all the way to 20mph or so, where the slugs would kick in, and we would speed back up. that was LONG trip from the PI Docks to Ridgeway...and we made 90 miles in 12hrs (of course, being the slowpokes, we were stuck in the sidings for other trains)

Anyhow--a great idea, a mostly good application, and a fair-to-midland crew comfort...

~~Nothing's perfect...

I thank you for the answers to my questions. If the idea of a slug is to add fuel to the consist, it seems reasonable, but the technology behind it seems extreme. The idea of dynamic braking seems the most likely. The cab control/breaking idea seems good, if the "heaters" worked ( a problem with the early F units ), and A/C was added to the cab roofs. This could be an answer to the noise problems in some of the locomotives on the road now. As a side, I have ridden in some units, a GP15-1, and an SW1500. The noise/vibration was not what I expected.
Thank you.
Play safe.

Dan.
PS. The people who complain about the noise of the trains should ride in one of the cabs, better yet, the stock/share holders !!! ???

A.B
Play safe.

PPS. What does "LOL" mean ?

DAN.

danzoyd872 Wrote:
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> I thank you for the answers to my questions. If
> the idea of a slug is to add fuel to the consist,
> it seems reasonable, but the technology behind it
> seems extreme. The idea of dynamic braking seems
> the most likely. The cab control/breaking idea
> seems good, if the "heaters" worked ( a problem
> with the early F units ), and A/C was added to the
> cab roofs. This could be an answer to the noise
> problems in some of the locomotives on the road
> now. As a side, I have ridden in some units, a
> GP15-1, and an SW1500. The noise/vibration was not
> what I expected.

My impression is that the primary purpose of slugs is to add tractive effort in low-speed applications -- such as locals, mine runs, and heavy transfer service -- without the expense of operating and maintaining a second, full-function locomotive. I was unaware that a GP40-2 plus slug actually has a higher horsepower rating than the GP40-2 alone, which if true obviously reinforces the benefit.


>
> PPS. What does "LOL" mean ?
"Laughing out loud"

DRLOCO Wrote:
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> The horsepower equivilants work like this:
> Slug + GP38-2=1 GP40-2(3,000hp) with 8 traction
> motors instead of 4.
> Slug+GP40-2=2 GP38-2's (4,000hp) with 8 traction
> motors equalling 8.

Whoa. It don't quite work that way.

Locomotives have two characteristics that are important when pulling trains: Tractive effort and rated horsepower. In simple terms, tractive effort varies by the number of axles, and horsepower by the output of the diesel engine. Tractive effort is important in that it tells you how heavy a train you can start and pull up a grade. Horsepower tells you how quickly you can move the train.

Looking at a GP-40 and comparing it to a GP-38, you get the following:

                  GP-38   GP-40
Tractive effort  52,000  52,000
Horsepower        2,000   3,000*

* There is a twist to the GP-40 HP, which I'll get into in a minute.

You can see that the tractive effort is identical, but that the GP-40 has more horsepower. That means both locomotives will pull the same weight of train, but the GP-40 will do it more quickly.

With a GP-38, you only have 2000 hp, as that is the maximum the engine can produce. When a slug is attached to a GP-38, the slug simply spreads that horsepower out over 8 axles instead of 4. With twice the number of axles, the result is twice the pulling power at less than about 10 mph. Above 10 mph, the locomotive becomes horsepower limited, and the combination would be no better than a single locomotive without the slug. There is no more horsepower, since the engine, which generates all the horsepower, produces the same output with or without the slug.

The unit/slug combination also provides the same braking effort as two locomotives, which can be an advantage over a single locomotive in switching service.

A GP-40 is a bit different. It only puts out 3,000 HP at speeds above about 18 mph. Below that speed, the engine is derated, such at at 12 mph it only produces 2,000 hp. This is done so that when a GP-40 is coupled to a locomotive like a GP-38, and operated on a heavy pull at 12 mph, with the horsepower matching the GP-38, the wheels won't slip excessively. It is called power matching.

By attaching a slug to a GP-40, the derating can be avoided. Thus a slug + GP-40 can operate at full 3,000 hp right through its operating speed range. It will pull a cut of cars 50% faster than the same cut pulled by a GP-38. However, since it has the same number of axles, it will be limited to the same weight of train when pulling it up a steep grade.

Thus, adding the information for the units + slugs to the above table yields:

                  GP-38   GP-40  GP-38+slug  GP-40+slug
Tractive effort  52,000  52,000    104,000     104,000
Horsepower        2,000   3,000      2,000       3,000

The idea of a slug is that it costs less than a full locomotive to maintain. If there is a need for tractive effort, but not horsepower, such as in yard switching applications, or slow speed industrial operations, then a slug can be useful.

In road service, slugs have questionable value, other than to gain a bit of horsepower out of the GP-40s between 12 and 18 mph. Above those speeds, the slug is essentially dead weight, costing maintenance and fuel to haul around.

.
> But then, CSX is too cheap to move the horns,
> instead paying out millions in hearing loss claims
> to the crews, while all the other class ones have
> moved the horns back mid-unit years ago...but I
> digress.
>

Im not sure but I think they may have started this already. Im not sure when this was done but SD40-2 8145 has the horn replaced back to the rear conductor side of the dynamic brake blister.

They really do the job as intended, esp. in slow speed situations. On a few occasions, I have forgotten to put the slug on-line until I realized that the SD-38 I was running was pulling terribly for the cut I had in tow. Adding the slug helped quite nicely. Out on the road and on branchlines, they prevent you from having to run long hood forward for half of the trip.