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All about locomotive rebuilders, small locomotive works, and experimental works

Moderator: Komachi

  by TerryC
How would you make a locomotive into a road slug? Could the fuel tank be used for extra fuel and what is the horsepower limit? What would need to be done to make a cowled freight locomotive into a road slug that hauls cargo like a boxcar or a Amtrak Cabbage*?

Keep asking, keep learning
* http://www.railpictures.net/viewphoto.php?id=1149

  by ACLfan
A "slug" is a locomotive unit without its engine. Usually, the engine (otherwise called a "prime mover") is removed and replaced with something of equivalent weight, such as concrete or steel, since weight is very important for tractive effort.

The traction motors are left intact, and the new slug unit must be coupled to a "mother" or control unit. The slug's traction motors operate in tandem with the "mother" unit's to produce the equivalent of two individual units. CSX added cab control features in its 2200 - 2300 series road slug units, so that they could actually be the lead unit, and control the "regular" powered units that each road slug unit was coupled to! The lack of engine noise and relatively cooler temperatures in the slug's cab were the primary reasons for this feature.

The slug's fuel tank could be used for extra fuel storage for the "mother" unit (and other units), provided that a fuel line siphon and pumping system was connected. Remember, the slug unit has absolutely no use for diesel fuel, as it no longer has an engine.

Don't confuse slug units with remote control units, as they are two very different critters! Remote control units are otherwise regular diesel locomotives, but have remote control technology that enable them to be controlled/operated without direct line connections.

Regarding the cowl units being redesigned for freight storage purposes, some form of weight replacement would be needed following the removal of the engine, as tractive effort is the remaining tangible value of the unit after the engine is removed. A lighter unit would have less effective traction. I doubt that the trade-off (extra freight storage space vs. loss of tractive effort) would be thought of as equal value. Additionally, there is the problem of having to disconnect the slug unit and leave it parked somewhere while it is being loaded/unloaded, since it is not going anywhere by itself!

As a history lesson, Baldwin and GM-EMD built combination passenger diesel units with baggage/freight storage compartments. They definitely were not a raving success! Only several demonstrater units were built and sold. No additional sales afterward. That was back when the Railway Express Agency was a big mover of merchandise freight (before FedEx and UPS!), and heavily relied on the railroads to move its less-than-carload freight business.

With today's FedEx, UPS, and everybody else in the freight pickup and delivery business, I can't imagine who would use the space created in a cowl (or any other unit) for freight shipping business.

On the other hand, it is a really cool concept for a model railroad operation!


  by fglk
Road Slugs in general cut in at about 5-15m.p.h. and out if the train gos over 30m.ph. this might vary from road to road thow I read this in a Conrail rule book.

The SOO Line had a Few Road Slugs that also served as Fuel tenders the hoods were choped and filled with concrete. The tracktion moters remained. I do beleve that these are still in use??

BC Rail also had some remote control M420 Mid Train Helper Road Slugs that had fuel tanks and traction moters as well these are no longer in service.

The Lehigh Valley Alco FB2's althow Cabless had cab controls, engions, and traction moters on them so that they could be moved about the yard.

  by RdHseRat
The Soo Line NEVER had any road slugs. The units that you are referring to were fuel tenders. They did not have traction motors. The were equipped with fuel transfer pumps at both ends of the fuel tank. We used air plane quick disconnect couplings and hoses between units. There were several shut-off valves to control the starting and stopping of the fuel transfer. The were a mechanical abomination!!!

Now with regards to actual slugs. It is not necessary to remove the engine and generator from the slug unit. If they are removed, then an equivalent weight must be added. It is extremely important the cow and the slug weigh the same. (wheel slip control.) One very important thing is the power for the traction motor blowers. The fuel tank on the slug can be used to complement the fuel tank on the cow. It is not a difficult modification

  by ACLfan
The Soo Line did have at least one combination fuel tender/yard slug (Soo Line #2118) that was converted from a SW1200 yard switcher. It was mated to Soo Line MP15 #1535.

Soo Line was considering converting one or more road units to combination fuel tenders/road slugs. However, I'm not sure that such a conversion was ever accomplished.


  by RdHseRat

You are correct that the 2118 was a slug. The big difference between it and the 4000 series fuel tenders were the amount of fuel capacity.

The only fuel on the 2118 was the original 600 gallon tank. None of the equipment inside the hood was removed. It was built primarily as a slug for the hump at Pigs Eye. It was also used as a test bed to work the "bugs" out of the fuel transfer system. We were very concerned about limiting a potential fuel spill.

The 4000's were a totally different ball game. With these abominations, everything above the main frame was removed and scrapped. We then had fabricated 4 fuel tanks complete with baffles to prevent sloshing, both laterally and longitudinal. Located on both ends of this tank were fuel pumps used to transfer the fuel. In addition, in this compartment were the controls used to monitor the transfer of fuel. The fuel was actually pumped out of the original under the frame fuel tank. This fuel tank was kept to lower the center of gravity for the tender.

The idea of using them as slugs was considered very early on in the process, but was dropped as being impractical very early on in the game. There were several reasons: 1. even with a full load of fuel they were much lighter than any other unit. 2. the fuel transfer would have caused a widely varying weight on the drivers. Both of these problems would have wreak havoc with any attempt to control wheel slip.

The reason that we used locomotive frames and EMD 4-whl trucks were to eliminate the problems that were happening with the BN fuel tenders. The BN was experiencing some cracks in the tank cars used as tenders. The FRA was upset because an independent brake application would not apply the brakes on the tenders when they were in the locomotive consist

  by fglk
Some line out there had combo Fuel Tender/Road Slugs could not rember who had them thought SOO Had them no need to get all bent out of shape about it.

  by RdHseRat

No one is bent out of shape. I was just trying to provide you with accurate information about road tenders on the Soo.

  by fglk
I'm sorry just been a bad day no hard feelings.

  by wess
BC Rail also had some remote control M420 Mid Train Helper Road Slugs that had fuel tanks and traction moters as well these are no longer in service.

If i remember hearing right, these M-420B,s were just cabless B units set up for remote mid train helper service. They never were shorn of their motors but were used as is til they were retired

  by sandpvrr
Hello All,
Just a word of caution - I've run into this talking about some Canadian roads up here in the Northeast - when a unit is dedicated for yard service on a Canadian road, they call it a 'Yard Slug' - it is a fully functional locomotive.
Down here in the US - a slug is a unit that is powered by a 'mother' unit, the slug has no means of powering itself, as has been mentioned above.
Hope this helps!
cya, Joey

  by fglk
Vary intresting Sandpvrr did not know that one.

  by trainmaster_1
sandpvrr wrote:Just a word of caution - I've run into this talking about some Canadian roads up here in the Northeast - when a unit is dedicated for yard service on a Canadian road, they call it a 'Yard Slug' - it is a fully functional locomotive.
Are you sure about that Joey ? I live next to the CPR and there is a yard a mile or two west to where I'm at they have yard units designated for yard service. And they don't call it a "Yard Slug", they call it a "Mother/daughter" pair, usually the GP9u is the mother and the older SW8's, SW9's and SW1200's are slugs "daughters" with just weights and tracton motors.

  by fglk
I've heard of Yard Goat being refered to a loco that is or has been retired to yard operations. Maybe the term Yard Slug has a duel meaning pending on what line we live along??

  by missthealcos
I've never heard that, CP doesn't generally use the term slug, they do use "mother/daughter" They also have control cabs, locomotives with only the cab equipment still in use, to avoid turning, and a few "control cab/daugters" =road slugs.

CN has alot of slugs, all for yard/hump use, some built new, some built from GP9's, a few left built from S3's

The BC Rail M420/M420B "slug" issue was tossed around in the mid nineties, but was never done.

I've never heard anyone anywhere refer to a fully functional locomotive as a slug.