Was it a local? UP's local around here runs with two GP's on either end of the train, facing opposite directions. The arrangement is for better visibility going up or down the line. I've seen it haul one boxcar before on a trip.
Locomotives use water rather than antifreeze in their cooling systems. Depending on temperature, it might be necessary to leave an engine running to prevent it from freezing up. New road engines have a system to monitor various parameters, including coolant temperature, and self start themselves should conditions warrant; but those systems are far from universal.
A local freight or a road switch may be hauling one car at that particular time but train length can vary during the run or from day to day. If the locomotives are facing in opposite directions, it may make the return run easier on the crew.
Let me add a bit because the wiser heads in locomotive operations haven't mentioned them.
If the locomotives are connected in MU, it may be simpler just to operate the two together under power (and use a smaller throttle opening, etc. to reduce peak power). There was a famous observation from Perlman's time on the Western Pacific that a consist of two EMDs working hard in Run 8 burned more fuel, for the same train resistance, than a consist of three similar EMDs sharing the load. Similar economics may apply to a train that may go from one or two cars to a train needing a good portion of the available HP during the day. What you can't see is the load that consist may be pulling even a few minutes later...
There are ways of idling 'unneeded' diesel engines in a consist -- we had a recent discussion of one, the Harmon Select-A-Power. A chief problem with these systems, in general, is that they can be very good at reducing power, but not quite so good at bringing it back up on demand. And you need the proper equipment to be installed.
One of the operating 'modes' for road slugs is transfer operations, where lots of TMs are needed to start the train, but one diesel engine can generate enough power to keep the train moving. CSX (on ex-L&N trackage) has been using these fairly extensively here for interyard moves. Crews should like riding in a quiet, air-conditioned cab far from noise, soot, and oily smells...
one would have more than enough power?
They were GE locos and everyone knows how slow they are to load up.
My personal favorite answer would be...If I have two good working units, I WILL have two dynamic brakes operating for SAFETY!!! As "Odd Ball" so wisely stated..."We like to be able to get out of trouble faster than we get into it!"
You never know when the only unit you have on line is going to fail. And, Mr. Murphy will see to it that it does fail and at the most inopportune time.
Be SAFE out there!
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To answer the thread title - a dead locomotive will have a drag coefficient very slightly more than a rail car of equivalent weight - locomotives weigh in between 130 tons and 215 tons. The additional drag comes from wheels rotating the traction motors as there is no way to disengage the gearing between the wheels and traction motors.
Local freights do a myriad of functions and to see one at a point in it's trip is not necessarily indicative of the work function it performs through out the entirety of it's trip. On my territory there is one local, depending upon the day of the week, can be handling a 9000 foot 14000 train on the outward portion of it's trip and less than a handful of cars on it's return trip.
Seeing a train, any train - anywhere, is like looking at a single frame of a full length movie that depicts the entirety of the railroad business.
Never too old to have a happy childhood!
Here in independence mo i have seen the local delivering cars using a GP38 and a slug mother. Technically speaking the slug mother is dead weight but not a drag on the train. It is quiet and much more comfortable than the unit with an engine in it.
rbandrHere in independence MO i have seen the local delivering cars using a GP38 and a slug mother. Technically speaking the slug mother is dead weight but not a drag on the train. It is quiet and much more comfortable than the unit with an engine in it.
Actually, the GP38 would BE the 'slug mother' -- the clever term for the unit that feeds the slug. (In the old days, when slugs were essentially just cut-down and weighted chassis, the 'mother' also provided discipline and control, but perhaps eerily mirroring some modern family life, a road slug can do perfectly effective control of its mother...)
The unpowered thing is the actual 'slug' -- we call it a 'road slug' to distinguish it from the original kind of (usually cabless) slug which added ballasted traction-motor capacity for humping and yard transfers. GE had an 'enhanced' form of slug they called a MATE (discussed in at least one early-'70s issue of Trains) which acted like a full locomotive (with transition, etc. allowing full-speed "MU" operation in mother-equipped consists. In the original concept, the MATE had no control cab, and acted much like an MUed B-unit with no diesel motor. Despite this, some form of the term "mate" has become popular to apply to road slugs that do continuous linked operation at all speeds, although I'm still old-fashioned and associate the term 'MATE' with its original maker/proponent -- much as I do with 'Cokes' or 'Kleenex' or 'Frigidaire'...
BNSF does run some control slugs, but they are quite distinctively different from 'normal' locomotives, unlike (say) some of the CSX units. Google TEBC-6 and tell me if that looks like what you saw.
See this old thread for more detail about the various 'flavors' of slug and MATE.
Overmod If the locomotives are connected in MU, it may be simpler just to operate the two together under power (and use a smaller throttle opening, etc. to reduce peak power). There was a famous observation from Perlman's time on the Western Pacific that a consist of two EMDs working hard in Run 8 burned more fuel, for the same train resistance, than a consist of three similar EMDs sharing the load. Similar economics may apply to a train that may go from one or two cars to a train needing a good portion of the available HP during the day. What you can't see is the load that consist may be pulling even a few minutes later...
They would rather have us using fewer engines working harder, than spreading the load over the entire consist. It used to be we could put another engine on line if we couldn't maintain speed within 10 mph of the train's authorized speed, but changed it to only being able to bring more engines on line if we we're in danger of stalling on a hill.
Jeff
I'm intrigued. In all my years of running, I've always heard the old saw that a diesel locomotive was most efficient when operating wide open on a train which utilized all that the units had to offer. I wonder if this is the case with more modern power, as opposed to the units being used in Mr. Perlman's time? At the present time, on the Baltimore division, we are instructed in intermodal service to run with only two units on line. We normally have three in consist, so in effect, we drag around 216 tons of dead iron. Of course, if a unit goes belly up enroute, it is handy to have a spare. But considering how rare such an event is, and the fact that a single unit can generally limp you into the next terminal, I wonder how much fuel we waste for "just in case". The Albany and Florence divisions hold to a no-less-than two HP per ton on intermodal trains policy. We frequently see that math stretched pretty good! Actually, with track work, following slow freights (and that pesky P301 VRE which averages 35mph,max) I sometimes think I could get the job done with an SW1!
Overmod One of the operating 'modes' for road slugs is transfer operations, where lots of TMs are needed to start the train, but one diesel engine can generate enough power to keep the train moving. CSX (on ex-L&N trackage) has been using these fairly extensively here for interyard moves. Crews should like riding in a quiet, air-conditioned cab far from noise, soot, and oily smells...
I was a conductor for CSX out of Wildwood, FL during 2001-2002. We used a road slug on one of the locals. It might have been quiet but it was not air conditioned, which really sucks during the Florida summers. Those type of jobs always had the oldest power. Don't even want to think about having to use the toilet as they were rarely cleaned.
I have a suspicion that the 'standards' have changed for these things, perhaps over the years. I don't recall seeing any road slug in Memphis service (seen since around 2010; don't remember exact times) that didn't have an air conditioner sitting up top. May have been evolution in the 'road slug' program as CSX and other roads discovered the advantages these things provided in running economy, particularly after 2007, and increased amenities (and perhaps maintenance quality) accordingly.
Brings up a peripheral issue: What specific methods can engine crews use to get maintenance staff to keep the toilets clean? Grievance procedure? Formal complaints and a request for discipline? Talks between unions, if the 'cleaners' are organized? (Maybe I'm exaggerating the procedures that are applicable in reality -- but what IS actually possible (perhaps different on a railroad-by-railroad basis) to get this fundamental working condition attended to?
You write it up on the work report. If it's really disgusting, you refuse the engine, maybe switch it to a trailing possition. If your in a terminal with shop personel, you can request that they come to attend to the offensive cauldren with magic chemicals. Occasionally, there are non-believers amongst the officialdum. They must be offered an audiance with the throne. This will generally convert even the most hardcore septic-sceptics. We are also never to take an engine with a strong chemical or bleach smell in the cab. I think somewhere on the system, someone was overcome by vapors. On the older power, you could open a valve beneath the hopper and dump the blue punch on worthy wayside trespassers. At high speed, spread over a long distance, the "evidence" is enviornmentally disposed of. Then just dump a bag of ice from the icebox in the hopper and you should be good to go! The best alternative is to use the running board nature potty for all but the most pressing demands, and try to make the other end of the road for big jobs.
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