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?
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