This rail fan and a retiree (not from railroad industry) wants comparison... if any, of standard diesel-electric locomotives, vs gen sets, vs slugs. How and where are they used ? First forum use, Thanks
pnc
From various spots around the interweb
Genset:GenSet technology (short for "Generator Set" or sets of engines turning a generator) replaces the large diesel engine and generator found in almost all existing freight locomotives with two or three much smaller diesel engines and generators. These smaller engines are similar to large off-road diesel engines and are EPA Tier III off-road / Tier II railroad compliant. Advanced computer technology allows for precise control of the engines, starting and stopping only as their power is needed.While the outward appearance of the GenSet is similar to existing, older-technology locomotives, fuel consumption and exhaust emissions are significantly reduced by using smaller engines only when needed.Environmental benefits of GenSets include:
Road Slug:
A railroad slug is an accessory to a diesel-electric locomotive. It has trucks with traction motors but is unable to move about under its own power, as it does not contain a prime mover to produce electricity. Instead, it is connected to a locomotive, called the mother, which provides current to operate the traction motors.
There is a good photo of one here http://en.wikipedia.org/wiki/Slug_(railroad)
Answering in automotive terms:
The 'standard' diesel locomotive is like a highway tractor (eighteen wheeler power.) It has a large, powerful prime mover that runs continuously, even when the loco is standing still or not even connected to a train. It is the best combination of speed, power and endurance, but its reliance on a single engine (large and difficult to change out) reduces reliability and adds to downtime when repairs are necessary.
A gen set is a single locomotive frame with several small diesel engines, each driving a generator. When standing or moving only itself, only one engine is running. The others start up and pick up their share of the load as horsepower needs increase. While that makes it more complex, it allows use of highway truck engine technology rather than marine/power plant engine technology. The gen-sets are mounted on pallets designed for quick exchange if one fails or is due for maintenance. Since there are several, a single engine failure doesn't kill the entire unit - it can still limp in at reduced speed.
A slug is rather like an extra set of drive axles that can be added to a highway tractor as part of the adaptation for hauling a heavy load. It doesn't increase the engine horsepower, but it does increase the starting and running tractive effort. The slug is a unit without an engine. It draws power from a unit which does have an engine. The speed of the whole is limited by the horsepower available and the load to be moved, and is most useful for starting and low-speed, high power applications.
Another concept is the Hybrid. Based on the concept that industrial switchers only need to develop full power for brief periods, while standing still most of the time, the Hybrid is like a hybrid car. A small diesel genset (as little as 185HP - same as a pickup truck) only runs to charge a BIG bank of batteries. The batteries can deliver up to 2000 HP at the wheels for a rather short time, then will recharge over ten or twelve minutes for each minute of full draw. Once the batteries are fully charged, the diesel shuts down automatically. In practice, the hybrids have had issues - even though the technology is the same as that of WWII diesel-electric submarines...
Just a rough-cut overview. Hope it helps.
Chuck
Most of the problems with hybrids seem to be with the batteries and the re-charging system. It also appears that they are more suited to use as industrial plant switchers than as yard switchers.
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