explain slug duties to me

[Anonymous]

i saw the BNSF 6218 & BNSF3970 working together reciently at barstow ca yard. both humping card and the putting together trains. does a slug just provide electrical power cause it sits so low to the ground?[:)]

[Eriediamond]

A slug is a unit that contains only weight and traction motors and is used with a switch engine. It prvides extra traction and gets it's power from the engine it is coupled to. They are used primarily in yards to make up trains and hump duties, but can also be used on local freights. Since they don't have any power of their own, they provide extra traction only and not extra horsepower. Now, having said this, I'm not a diesel expert and may stand corrected by someone with more diesel knowledge. Ken

[Anonymous]

Ken's spot-on. A slug is effectively a set of powered trucks and a frame - it draws power from the loco it's coupled to. The reason behind this is that the loco can produce more power than it can put on the rails at low speed (hence wheelspin at starting) - the slug spreads the available power over more axles and enables it to be used more effectively.

[csxengineer98]

basicly its extra traction of 2 locomotives but only useing fuel of 1 unit... they are used mostly where slower speeds but higher tractive effort is needed...such as in a yard... now csx has a fleet of road sugs...they are a mother unit (the one with the engin) and a slug (the unit that has a cab..but no guts)...they use them alot on locals and in flat switching yards.....
csx engineer

[Anonymous]

he, are u really an engineer, for CSX?

[csxengineer98]

yes..i am a real engineer for csx
csx engineer

[Anonymous]

what about calf units that are sometimes coupled up to diesel switchers? what about them?

[BR60103]

Calf units are the B units of switchers. They have engine and electric motors, but no cab. (There are controls, but no comfort). Again, yard duties, possibly inter yard duties.

[Anonymous]

ok, thanks

[CSSHEGEWISCH]

BRC used their cow-calf sets as hump pushers, pulldown engines and on transfers, although they were replaced as hump pushers by BRC's heavily ballasted GP38-2's (490-495). BRC 526 was an SW1200 that was converted to a slug plugged into an SW1500 for various yard duties. BRC's six-motor slugs are plugged into derated SD40's for hump pushers.

UP originally used its TR5 cow-calf sets, which were equipped with dynamic brakes, as helpers over Cajon Pass.

[Anonymous]

And the BNSF 6218 is radio remote control equipped. The BNSF also has some old switcher frames with no traction motors or engine (called a prime mover) and the cab blocked off. The do have a small diesel gen set for electrical power for the radio remote control equipment. They can be coupled to any other type of locomotive to be used in remote control yard operation by a single trainman. It's kinda like a slug but sorta in reverse.

[BaltACD]

The CSX Road Mother-Slugs, which are all 4 axles, GP38 & GP40's for the mother and a variety of models for the slugs from GP30's to GP40's.

The power generation characteristics of diesel electric locomotives has more current available at low speeds than as single locomotives traction motors can safely consume (short time ratings etc.) Adding the traction motors for the slug, to the draw for the locomotive and you have the ability to consume all the current that the locomotives generator can produce without getting the power consumption of the traction motors into the overheating zone of short time ratings. On CSX sets, once speed gets up to 25 MPH, only the mother has power going to its traction motors as all the current generated at ths speed can safely be consumed by the locomotive. With near tonnage trains (which is about all CSX operates) a mother-slug engine consist has a practical top speed of 25/30 MPH, as the single engine does not posess enough horsepower to go any faster. For tonnage rating purposes the mother and slug are both rated for the same amount of drag tonnage.