I watched a loaded unit train of grain grinding along the flat prairie. Unusual for our area, the train had a single locomotive on the point and two on rear. The DS units on the tail didn’t seem to be working very hard. Is there any appreciable difference in train handing with 1/2 set-up verses 2/1?
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CN's operating rules do not allow a remote consist to have more powered axles than the lead consist so I can't comment much on this, other than to say that the train may have been moving slowly due to some type of speed restriction, not lack of power.
On short trains or empty unit trains with remotes you tend to get a bit of a run-in of slack when the remote pushes the tail end over a hill.
Greetings from Alberta
-an Articulate Malcontent
See this thread from 2015 (also by Murphy Siding):
Push me / Pull you - http://cs.trains.com/trn/f/111/p/250896/2799921.aspx
For another form of motiver power (also from that thread):
https://en.wikipedia.org/wiki/List_of_Doctor_Dolittle_characters#The_Pushmi-Pullyu
and
https://runllalpacarun.files.wordpress.com/2011/01/pushmepullyou1.jpg
- PDN.
Just so I'm clear.
Is my understanding correct that the DPUs can be controlled totally independently? The lead lash-up could be in notch 5, while the pushers are in 3? Say there are 3 engines up front and 2 pushing. In my above example, the lead units are all in 5, while both of the pushers are in 3, correct? IE, any lash-up (whether or not there are DPUs) is always run as a single operating entity, right?
Finally, if there are two DP lash-ups (mid and end), then the engineer has three separate controls?
Lithonia Operator Just so I'm clear. Is my understanding correct that the DPUs can be controlled totally independently? The lead lash-up could be in notch 5, while the pushers are in 3? Say there are 3 engines up front and 2 pushing. In my above example, the lead units are all in 5, while both of the pushers are in 3, correct? IE, any lash-up (whether or not there are DPUs) is always run as a single operating entity, right? Finally, if there are two DP lash-ups (mid and end), then the engineer has three separate controls?
The DPU can be controlled separately from the leading locomotive. I believe it's usually referred to by "the fence." Fence up = separate, fence down = tied together.
One could be in dynamics while the other is under power, if the profile calls for it.
Can't speak to having multiple DPUs - kinda curious myself.
Just saw an intermodal at Deshler (CSX) with one loco in the lead and a two unit mid-train DPU...
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With one in the front and two in the back, the crew will feel more slack action because the head end can't pull away from the train going through sags, etc. The thing to do would be run the DP set in lower throttle notch settings than the head end.
You can have the lead consist in dynamics with the DPs in power, but not the other way around. The only way the DPs could be in dynamics while the lead is in power would be to a communication loss. During comm loss, the DPs maintain there last command. In power for 90 mins, in dynamics until comm is restored. The air brake can be used to signal the DPs to idle down during comm loss.
With multiple DP consists, say A (lead) B (midtrain) and C (rear end) you can run them all "in sync" or the "fence" down. You can have A and B in sync with C independent, fence up netween B and C, looks like this A B/C. You can also have B and C together but independent of A, fence up netween A and B, looks like this A/B C.
I'm not sure of the combinations of 4 or 5 DP consists off hand. The combinations will only allow lead and one independent combination. Each consist can't be operated completely on their own.
I just had a train with mid and rear DP consists. (It was 2x1x1, 18000 tons, 14800 feet.) It ran better than I thought, but I was concerned through part of the run where there are three sags close together. Because the consists can't be ran completely independent.
Also, depending on the train, not all engines in a DP consist may be on line. We used to have a manifest that usually had 4 or 5 engines in an A-B consist. The Mid train (B) set and all the cars behind it would be set out at an intermediate crew change yard. Of those mid train engiines, only one or two would be on line.
Jeff
Jeff, I'm still a bit foggy on this.
If a single engine consist is MUed together, can the engineer run any engines in that consist at a different throttle notch than the lead unit? I have always assumed not, but I don't actually know. (I don't know why one would want to do this, btw.)
Also, say you have a 3-unit consist pulling a train, and there's a road foreman or electrician or somebody riding in the cab of the second unit, for the purpose of checking out a problem. Could one of those people take that engine out of MU mode, and run it manually, in a different notch than the lead unit? And if that's possible, could the lead engineer still control the 3rd unit in sync with the 1st. (Can the MU-ness bypass an engine that's being run independently?)
I'm just bumping my post above up. Can someone answer those questions for me. Thanks.
Lithonia Operator Jeff, I'm still a bit foggy on this. If a single engine consist is MUed together, can the engineer run any engines in that consist at a different throttle notch than the lead unit? I have always assumed not, but I don't actually know. (I don't know why one would want to do this, btw.) Also, say you have a 3-unit consist pulling a train, and there's a road foreman or electrician or somebody riding in the cab of the second unit, for the purpose of checking out a problem. Could one of those people take that engine out of MU mode, and run it manually, in a different notch than the lead unit? And if that's possible, could the lead engineer still control the 3rd unit in sync with the 1st. (Can the MU-ness bypass an engine that's being run independently?)
The trainline MU system is all or nothing. All units connected together will be in the same throttle notch.
A certain fuel conservation system may be able to do this (Jeff, please elaborate).
It is possible to disconnect a jumper cable and have a second Engineer run the unit(s) at the rear of the consist in a different throttle notch while all the air brakes are still being controlled from the original lead unit. But you cannot do this with a middle unit and still have the trailing unit be "in sync" with the original lead unit.
SD70DudeA certain fuel conservation system may be able to do this (Jeff, please elaborate).
http://s7d2.scene7.com/is/content/Caterpillar/C10669469
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
SD70Dude Lithonia Operator Jeff, I'm still a bit foggy on this. If a single engine consist is MUed together, can the engineer run any engines in that consist at a different throttle notch than the lead unit? I have always assumed not, but I don't actually know. (I don't know why one would want to do this, btw.) Also, say you have a 3-unit consist pulling a train, and there's a road foreman or electrician or somebody riding in the cab of the second unit, for the purpose of checking out a problem. Could one of those people take that engine out of MU mode, and run it manually, in a different notch than the lead unit? And if that's possible, could the lead engineer still control the 3rd unit in sync with the 1st. (Can the MU-ness bypass an engine that's being run independently?) The trainline MU system is all or nothing. All units connected together will be in the same throttle notch. A certain fuel conservation system may be able to do this (Jeff, please elaborate). It is possible to disconnect a jumper cable and have a second Engineer run the unit(s) at the rear of the consist in a different throttle notch while all the air brakes are still being controlled from the original lead unit. But you cannot do this with a middle unit and still have the trailing unit be "in sync" with the original lead unit.
Thanks, Dude.
zugmann SD70Dude A certain fuel conservation system may be able to do this (Jeff, please elaborate). http://s7d2.scene7.com/is/content/Caterpillar/C10669469
SD70Dude A certain fuel conservation system may be able to do this (Jeff, please elaborate).
Ah, Smart Consist. A good idea that they screwed up.
They did 'refine' it, but it still isn't really smart. Unless all you care about is saving fuel (money), but despite their 'findings' I don't think it ever really did.
You used to have to initiate the system and were able to turn it on/off. I haven't seen it on any of our EMDs for quite a while. Some say it's still there, lurking as an automated system within the computer.
When you throttled out, SC would decide how to run the consist to meet the desired power level. When initiating the system you log in what types of engines are in the consist. (It had a more detailed EMD list, including GP7's, but had GE models, too.) Say you had three engines on line. If you went to throttle notch 5, instead of all three going to notch 5, SC might determine that it was better to have the lead go to notch 1 or idle, the second engine to notch 7 and the third to notch 3, or something like that. It didn't seem like the newer, more fuel efficient engines necesarily were run higher than the older, less effecient engines. I don't know how they arrived at their programming, but it did seem like it liked to run GE engines in higher notches. Almost like it wanted to show GE's using more fuel.
They did update it so it wouldn't drop the load on the lead engine. Even then it really didn't work as far as train handling goes. No one, engineers or field level management liked it.
Before my time, I remember reading about a system where engineers could manually reduce trailing engine(s) once you got up to speed and didn't need the extra horses. I think that wasn't too popular or didn't work out and eventually went away. If SC would have done that, it might have been better.
jeffhergertThey did update it so it wouldn't drop the load on the lead engine. Even then it really didn't work as far as train handling goes. No one, engineers or field level management liked it. Before my time, I remember reading about a system where engineers could manually reduce trailing engine(s) once you got up to speed and didn't need the extra horses. I think that wasn't too popular or didn't work out and eventually went away. If SC would have done that, it might have been better.
Doesn't GE have something similar? I don't run the new crap much at all. Granted we have some old engines that like to save fuel and shut themselves down when they feel like it, but you know... PS something or other.
Conrail had select-a-power. I think that allowed you to drop engines on teh fly.
If GE does, it might be within their 'Trip Optimizer" energy management system. When engaged it can access, at least on the lead engine, half-throttle/dynamic brake notches. The engineer only has notch 1, 2, 3, etc. T-O has notch .5, 1, 1.5, 2, 2.5, etc.
[quote user="zugmann"
http://s7d2.scene7.com/is/content/Caterpillar/C10669469[/quote]
I suspect he was thinking of Harmon Select-A-Power, which let you selectively idle individual units in a consist that is suitably equipped. To my knowledge this didn't let you adjust the individual power via run/rack setting or limit peak notch on selected units ... it just let you take them on and off the line with a convenient cab selector. I suspect Don Oltmann will have some interesting recollections...
The Amtrak P42s had a special switch that would limit power on the lead unit to 7th notch, but this isn't 'just' for fuel saving. It might seem piddling except that the mighty 7FDLs in the power on the City of New Orleans northbound would routinely set off car alarms in the riverfront parking garages as they throttled up coming off the bluff; I can easily imagine what it is like in the cab in full Run 8...
The switch that limited power to the 7th notch was useful for slippery rail conditions. The lead unit would condition the rail and drop sand with its power reduced while the trailing units, operating on improved rail conditions, could be kept at full power.
Mark Vinski
For trains with only power on front. Instead of running the 27 point connection run the trailing unit(s) thru the DPU system. That way engineer can have fine control. A thought NS for a while had many of their locos set for a power reduction at run 8. Is that still the case ?
Why would you DP it?? Litterally no engineer wants to run DP unless it's absolutely required. In certain situations I'll idle the DP and just run conventional if I'm not in the hills. It's just a bunch of extra work to deal with.
as for consist control EMD has Smart consist where You have to tell it what type of engines you have on your head end consist, and GE has smart HPT. I really haven't messed with either too much yet, because my class 1 hasn't forced it on us YET.
GE trip optimizer has consist control now, it can control each engine in the consist independently. You can watch it run and it will put a little box on the screen that says TRIP OP POWER and itll start messing with the trailing engines going to idle and stuff like that. you can definitely feel it when it happens, and when you take manual control of the train from T.O. it still will control your trailing motors, until you start notching up hard and then it'll slowly give them back to you.
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