I have what may seem to be a silly question, but I am a newer conductor and my engineers don’t know the answer, but how do slugs work are they using the power from the leader or do they have thier own engine that turns the traction motors just no cab and controls
Thanks
Slugs draw their power for traction from their mother unit. There will be some extra cables between the slug and slug mother for this connection.
…Isn’t part of the idea to create “slugs”, is to take advantage of more tractive effort available so more of the power of the prime mover can be utilized.
If your engineers don’t know the answer, their qualification procedures are seriously lacking in their mechanical component. Engineers had better know which units have prime movers and which ones have a lump of concrete in the ‘engine room’.
Is it appropriate for me to point out that not all slugs are cabless? CSX has quite a fleet of slugs with cabs and controls. They ought to be a nice, clean, quiet place from which to control a consist.
I think I’ll add an appropriate [;)] here.
Slugs are only effective at low speeds, and where the extra tractive effort to start a train is required.
At low speeds, the locomotive usually can produce more power than the adhesion force can apply, thereby causing the wheels to slip. With the power of the prime movers distributed to more traction motors, the tractive effort goes way up. It’s kinda sorta why a six-axle locomotive is better at starting a train than a four-alxe: more traction motors to utilize the power.
Slugs are great for yard work, or for very heavy slow-moving trains. After a certain speed (which I do not have exact figures, and which varies depending on the usual factors: tonnage, horsepower, speed, etc., but I would give a semi-educated guess of around the old series/paralell transition point [20-25mph]), the slug becomes extra tonnage to haul around.
…Zardoz…That is exactly the discription I had in mind. Local yard work, starting, moving large cuts of loads, etc…with the one prime mover distributing the effort along the many traction motors which are carrying weight of the {loaded}, engineless unit, hence more T E.
I have only seen them in our hump yard I haven’t ever seen any on the road I got off the road and I’m working the yard extra board since the road was so slow most of the engineers in the yard are old heads and probably forgot but I still think its strange that they didn’t know or either didn’t want to tell me
I seem to vaguely recall that slugs were used on mainline freights by some road. Was is SCL or ACL?
I think I am going to use this opportunity to say something nice about CSX, because I don’t think I have ever done that before . . .
CSX’ slugs are pretty cool. You get to see–what is left of them at least–GP-30s due to CSX. Better yet, they are not just in yard service. I regularly see them on a regular local that serves a branch line in south east Indiana near Cincinnati. Also, you can see them on the high iron on CSX’ Chicago-Evansville, ex CE&I line.
I was once told that they automatically shut off at 25 mph.
Gabe
SCL had MATEs built in the early 1970s for their Florida phosphate trains. They were built on U36B frames, and worked with them.
THe C&NW rebuilt several locomotives into road slugs as well.
…A Slug set…see use on the S&C over in Pennsylvania a CSX branch running from Rockwood to Johnstown. At least I’ve seen them in recent years doing so and Brian of Somerset has photographed them on that branch. Branch would be 40 - 45 miles in length. I know of one grade reported to be at about 3% for a short distance. It’s an old coal hauler. But the Slug and Mother engine aren’t being used for that, believe it was just misc hauling, etc…
An engineer once told me that a slug helps alot up to about 8 or 9 mph, after that he could hardly feel the slug pulling. But l guess this also has to do with gearing.
l thought BCRail used road slugs with one slug shared between 2 units,… way up north.
[color=blue]At low track speeds, diesel-electric engines are able to generate more electrical power than a single engines traction motors can use, thus there is ‘surplus’ electrical power available to power the traction motors on the slug.
Electric motors develop their maximum torque at their lowest operating speeds, as the operating speeds increase the torque diminishes. All DC diesel electrics have a ‘short time’ rating plate applied to the operating console…this is the amount of time the traction motors can handle the specified level of amperage without overheating the traction motor wiring to damaging levels. If the short time ratings are exceeded the traction motors will sustain heat damage to their wiring (burnt up). Slugs make use of this excess power up to the point of the short time ratings point. All DC diesel-electrics have a specified ‘minimum continuous speed’ this is the speed where full electrical power can be sent to the traction motors without getting into the short time ratings. Once minimum continuous speed has been achieved the electrical power available to the slug begins to sap electical power that is available to the locomotive powered unit.[/color]