As the question says… The caption for this pic raised the question…
http://www.railpictures.net/viewphoto.php?id=84718
When did they start to be used please?
TIA [8D]
Hmm…I belive early 90s. Road slugs lack the “prime mover” (the technical term for the locomotive’s diesel engine), but retain the cab, controls, and traction motors/dynamic brakes of a locomotive. They are geared for road service.
Yard slugs, in addition to not having a “prime mover”, have no cab and are gearing for low speed/high traction switching service.
All slugs draw their power from their “mother”.
Nick
An RV driving down the highway at 10 -15 under the speed limit. Oh, you mean
trains? [:D] That is a ballasted platform rebuilt from an old locomotive equipped
with traction motors but no prime mover which gets its electrical energy from
a normal locomotive coupled to it. These are used where high tractive force
is needed but not necessarily high horsepower-like drags or transfers.
Generally low-speed heavy haulage service. Not all road slugs have cabs.
Some do have dynamic brakes (N&W ex GP9 slugs, for example). Road slugs
have road-type trucks. Yard slugs frequently do not.
The slug concept dates at least from the 1960s. Northern Pacific Railway
rebuilt 3 old Baldwin yard switchers as yard slugs and assigned them
to the Pasco, Washington hump yard with SW1200s as mothers. Can’t
say about road slugs.
On shortlines, almost all slugs are “home made” by the railroads. Some of the poor railroads will pour the engine compartment full of concrete after the prime mover dies as the locomotive is not worth fixing and they have no money for another. They then power them with one still running ( and run it close to 100%) and the slug doubles the starting tractive effort but the top speed of the set is severly limited. So they can still pull big trains, but only about 30 mph LOL. Of course their track is poor so 30mph is about it anyway. Most slugs look just like real locomotives other than no smoke comes out. LOL You will almost never see a slug out on the BNSF or CSX mains BTW. The slugs we tend to model are the ones that have had the body modified by the roads, they remove the cab and lower the hood, it only takes a few foot of concrete to equal the weight of a prime mover. I have heard this is done most of the time not to make the slug look better or different, but to use the cab and hoods on a wrecked unit that is mechanically sound. Fred
The Southern Pacific was testing some before 1980. They were called “mates” and were on loan from an eastern railroad where the were already in use.
Slugs in yard service date back to the 1950’s. NYC converted several of their tri-powers to slugs for use with modified switchers as hump pushers.
C&NW may have been the first road to use road slugs in the early 1970’s. They cut down two ex-CGW RS2’s and various F3B/F7B’s to road slugs for use between two GP35’s or C425’s on the Huron line (now DM&E). The trains were heavy and speeds were low because of poor track so the road slugs proved useful.
SCL bought 4-motor MATE’s from GE, a rare example of a factory-built slug, at about the same time. They worked with modified U36B’s on phosphate trains in Florida.
TRAINS had an article in the mid-1970’s or so which explained slugs quite thoroughly.
I know for a fact that the Kansas City Southern (KCS) has been using yard and road slugs since at least the early 80’s. The first one I checked out was an old F7.It had a big block of concrete where the diesel engine had been. All the electrics had been rerouted so that it was fed from another locomotive. I don’t remember the exact # of the unit, but it was in the 4050 series and was run as a slug for quite a few years before finally being scrapped.
[soapbox]
CSX’s Road slugs are geared for 65 MPH, they are widely used in local and helper service.
Nick
Yup, CSX road slugs are indeed used for full-speed road service, and the crews actually like using them to lead a consist because it’s nice and quiet.
Southern Railway built quite a few yard slugs in the late 40’s, early 50’s,and all the way into the 70’s, and used them between 2 yard switchers. Southern even used “brake units” prior to that, which were simply cut down tenders, ballasted with concrete, and brakes set up to operate with the “mother” unit’s independent brake. Kept from having to air up the whole train in a yard, and very handy when hump yards were just beginning to be used. Of course, these were scrapped when slugs came along, as slugs were just the logical “next step” from the brake units.
I’d have to get out my book to see exactly when the yard slugs came along, but that’s what my memory tells me at the moment.
Brad
SP had 14 road slugs called TEBU’s (Traction Effect Booster Unit). They were made from cut down U25B’s, and drew their power from a pair of GP40 mother units. This spreads the power from each GP40 over 2 additional axles, giving better traction at low speed. They then cut out at higher speeds, probably around 35-40 MPH. Here are a couple of pictures:
http://espee.railfan.net/nonindex/tebu_photos/1603a_sp-tebu-brian_paul_ehni.jpg
http://espee.railfan.net/nonindex/tebu_photos/1607_sp-tebu-rob_sarberenyi.jpg
The TEBU’s retained their fuel tanks, so they acted as fuel tenders. They also kept their dynamic brakes.
As I recall, SP used them for taconite trains in Texas, and lumber trains in Oregon. Both involve heavy drag freights, and can need a lot of traction to get started.
Milw used some 3 unit F-7 sets as power for log trains running into Tacoma. The A units were normal and the Bs had all the roof goodies removed w/ smoth sheet metal applied over the resulting holes. The fuel tanks were also removed and I believe the side port holes were plated over. The east truck on the B drew current from the east A unit and the west truck on the B (they were ABA sets) drew current from the west A unit. They would sometimes run two sets MUed for a total of 24 traction motors and 4 diesel engine/generator sets.
CSX is still running the GP30/GP35 slugs? I haven’t seen any of those in awhile.
Here are some CSX slugs:
http://www.rr-fallenflags.org/csx/csx1015asm.jpg
http://www.rr-fallenflags.org/csx/csx1016d.jpg
http://www.rr-fallenflags.org/csx/csx1038as.jpg
These (except for the last one, that’s a former GP7 or GP9) were made from retired 6-motor Alcos. They’re used in yard service, sometimes with an SD38.
…and now for some road slugs.
http://www.rr-fallenflags.org/csx/csx2202adm.jpg (former GP40?)
http://www.rr-fallenflags.org/csx/csx2259ahh.jpg (former GP30)
CSXT 2202 is a former GP35.
Nick
In 1914 the Butte Anaconda & Pacific took delivery of two “tractor truck” units with a third recieved in 1915. They consisted of a power truck ballasted to 40 tons with mechanical equipment necessary to MU with their GE 80 ton freight motors. Although mated to electric locos (diesels didn’t exists) they are a precursor of the diesel loco/ slug combo.