Railroad Forums 

  • Motive power question

  • Discussion of present-day CM&Q operations, as well as discussion of predecessors Montreal, Maine & Atlantic Railway (MMA) and Bangor & Aroostook Railroad (BAR).
Discussion of present-day CM&Q operations, as well as discussion of predecessors Montreal, Maine & Atlantic Railway (MMA) and Bangor & Aroostook Railroad (BAR).

Moderator: MEC407

 #29457  by Cowford
 
Given that MMA has been and will always be looking for economical alternatives in the motive power front... why have they not (or have they) considered slugs?
 #29649  by sandpvrr
 
Hello Cowford, and all,
First - I must mention a personal, strong, anti-slug feeling. That having been said, they do have their uses, mainly yard duties, in my opinion.
MM&A has no hump yards, a major haunt for slugs. MM&A has in my humble opinion, very good power utilization. Many of the so called 'yard jobs' Millinocket Mill switchers, for example, run with power that during the previous day brought in a road job.
Slug/mother combos (particularly home made ones) are usually built for yard service, and are completely useless out on the road. This effectively ties a loco (the mother) down to permanent service. Should the mother unit die, the slug is useless. Now you're out the power from two locos for yard switching.
Road slugs, like Saint Lawrence and Atlantic's, have proven very troublesome, at least down there, I hear that CSXs do very well. Why, I don't know, but just from a electrical stand point, I can take a guess.
Virtually all the issues with locomotives on the MM&A last year were electrical, mostly traction motors. With a slug, you have two sets of traction motors, plus additional management electronics, running off of a generator that provides more power than a standard unit generator would, but not much more. What you're doing is pushing the generator harder, by doubling the load, and adding more electrical problems to deal with. Electrical problems in any system are much harder to troubleshoot than mechanical problems. Adding a slug to a unit not only doubles the load on the generator of the mother, it triples the electrical potential problems. You now have three systems on one generator - Mother electrical systems, systems to transport the power from the mother to the slug, and slug electrical systems. A problem in any of the three, can throw the other two off, which makes the real problem even harder to find.
Judging by what I've heard on one occasion when a slug died on the SLR (via scanner) the first troubleshooting that was done was to shut the slug off, and isolate it from the mother. Good strategy, it eliminated two of the potential trouble spots, transmission and slug electrics. Turned out to be a problem in the mother, and because of the way the slug and mother were wired together, one traction motor had to be cut out on the mother, which shut down one on the slug as well.
The slug was fine, but because the mother had a problem, the whole situation was made worse.
Comments anyone?
cya, Joey

 #29672  by MEC407
 
For what it's worth, those slug&mother sets on the SLR were rebuilt by GE, with GE electrical/electronic systems. ;)
 #29934  by Realityrail
 
MM&A could use slugs with the B39-8 units as mothers, BUT:
1) The B39-8 units have excitation and wheel slip controls that are solid state
2) These were some of the first controls of their types, and they used preprogramed electrical circuits, or "burned Chips"
3) To use these units as slug mothers would require a reprograming of these components-burning of new chips-as well as the associated program changes
4) GE is the only company with the details associated with these chips and the programing
5) The costs to do such programing and burn the chips would be high, the lead time long and the end product? Not worth the bother.

Can the C30-7 units be used as slug mothers? Sure, but when or what do you gain on the road jobs with slugs? Nada, zip, nothing, not a thing.

SLR has had their slug problems-but SLR is a tiny player compared to MM&A.

 #30016  by sandpvrr
 
Hello All,
Another thought that just popped into my head - slugs were traditionally made from units that the railroad owned and had slipped into disrepair. I recall seeing a picture of a RS-11 made into a slug paired with an EMD mother. Railroads have been traditionally very good at recycling.
With the current trend of leasing power, could we be seeing the end of the slug on regional railroads?
RealityRail brought up a good point - road slugs seem like a contradiction in terms almost, but why does CSX have a bunch of them? Does CSX see something in the slug that the rest of us don't?
Just some thoughts...
cya, Joey

 #30265  by Cowford
 
I am a "CSXer" but not a power guru... we use them pretty extensively in the Bone Valley and as supplemental power on switching/yard jobs. I understand they lose their benefits at road speeds... I'm not sure what the speed "wall" is. I know BM tried a road slug at one time mated with two GP-40s... apparently the benefits were not significant enough for a repeat. I didn't know SLR had such units. Nowadays, I couldn't tell a GE from an EMD. (Sometimes the vocation dampens the avocation!)
 #30323  by sandpvrr
 
Hello All,
Just to clarify a couple of things, to prevent confusion.
The SLR slugs (there are a total of four mothers and four slugs) were made from EMD locos, and use pretty much stock EMD carbodies.
Two of the mothers were owned by SLR previous to their conversion, and were GP-40Xs. The other two are new to the SLR, and I think were straight up GP-40s. The slugs came from converted GP-38s, and are new to the SLR.
Although EMD based, the slug conversion was done in Mexico to GE specifications, and includes a computerized locomotive management system, as opposed to a switch and relay type of operation. This management system is apparently supposed to improve efficiency.
Another interesting feature of the SLR slugs is that they also serve as fuel tenders for the mothers, all have fully functional fuel tanks, and can feed the mothers should they run out.
I have been been told, but can't confirm, that above 10 MPH, the slugs are cut out and are apparently dead weight.
Hope this helps!
cya, Joey