Reading the latest issue of Classic Trains and it got me wondering. If a diesel train has a number of helper locos hooked together, does the lead engineer have a single control for all the helpers, or does he have a separate control for each?
I’m pretty sure of the answer, but not certain…
Not quite sure what you are asking about. Are you asking about Distributed power sets where there are multiple sets of iengine in the train and one engineer is controlling all of them or are you asking about multiple engines in one consist, all coupled together in one group?
DP engines are all controlled by one engineer and he only has one control stand, but he can control individual DP sets in the train.
Engines all in one consist are all handled together, but he can manually set some engine up to be off line (running but not pulling).
As with our models, I’m wondering if the engineer has problems matching individual loco speeds when in a consist…
Short answer, “No”. Model engines are directly geared to the motor. Real engines are diesel electric.
May be a bit off topic, but the CN runs a short haul manifest, train A415, from Stevens Point, WI., to Green Bay. WI., and back, with a loco and engineer on each end.
No other crew, just the 2 engineers.
Mike.
The Bessemer & Lake Erie ran them like that for a while, too. Albion, Pa. to Conneaut, Ohio ore docks.
Cut the power off each end and move over one or two yard tracks and tie on to another hundred-car cut. Usually loads south, empties north but they did haul coal north, too, but I don’t know how often that happened.
A crew could make two round-trips a day like this.
bessemer 089 by Todd Dillon, on Flickr
I rode along one night and noted that the lead engineer hardly touched the throttle at all. Up to run-8 once the train got rolling and the throttle stayed there until we got close to the curves and down-grade near the docks.
I imagine it was the same at the rear.
Regards, Ed
i’m curious
presumably a “consist” is 2 or more engines that are coupled together and distributed power means there can be multiple consists in a train separated by rolling stock.
presumably all engines in a consist have a physical electrical connection between them. are distributed (?) consists controlled from by the engineer using radio? if so, do the engines automatically shut-down if the radio link is lost?
i can understand that any engine is turned off (no longer providing traction). but if there is a single control stand, are all consist/engines in the same “notch”? and does this result in equal traction by each engine or do they simply provide whatever traction (i.e. power) that notch results in for that engine considering engine size (HP), age and any other performance deviations
i think the OP was asking if prototypical engines ever “slip” like some consisted models do because they are not properly speed matched?
is this an example? what caused this?
Correct, sorta. A consist could be one engine. Distributed power is separate groups of engines (I think there can be up to 6 or 7) controlled by one engineer.
Yes and yes.
There is only a penalty if contact is lost for a certain length of time. Momentary loss of contact happens all the time. Cuts, overpasses, buildings in cities, power lines, and other things can cause loss of a signal.
Normally, unless the engineer changes something, yes.
No.
Yes, just like every engine in every consist controlled by any method.
DP first. A DP consist in power mode will maintain the throttle position of the last command it received for 90 minutes during extended communication (comm) loss. After that it will cut out it’s brake valve and go to idle. It will remain that way until comm is restored.
If an engineer wishes to cut the power to the DP earlier, making a automatic brake application will signal the DP(s) to isle down.
A DP consist in dynamic braking will remain in dynamic brakes indefinitely until comm is restored. This is because there may be times when, like on a long down grade section, you might not want to lose dynamics.
If you need to get out of dynos, ther is away once stopped. An emergency application when stopped will signal the DP(s) to go to idle and cut out the automatic brake.
About all being in the same notch on a “hard wired” consist. There are some energy managment systems that the onboard computer may run different engines within the consist in different throttle notches. The engineer places the throttle in a certain notch. The computer may decide that trailing engines will be run in the “optimal” n
An elementary video about DPU by a locomotive engineer:
https://m.youtube.com/watch?v=MuVRAg3HS-4&feature=youtu.be
And a tutorial from the train-simulator community about setting up DPU and then starting a heavy train on a grade – note the helpful things in the comments…
Mark Cole, who helped write the ATSF manual for Locotrol II in the mid-'80s just before the aborted SLSF merger, noted that in the revision from the original to II, the Harris engineers incorporated “too many safety items which caused the trains to go into emergency whenever something wasn’t exactly what the equipment required”. I suspect much of the way later versions handle ‘indefinite LoS’ was “informed” by such experience.
There can be issues with the loss of signal. I still remember the original uncensored video of the Panhandle wreck, where the head-end radio was destroyed on impact and the DP kept pushing the train into the developing dust cloud…
thanks
fly-by-wire was developed during the space shuttle era as a means to control an aircraft electrically via computer or even remotely (!!). initial systems only gave the computer 20% control which was presumably enough to relieve the pilots of the need to make frequent adjustments reducing fatique.
another feature prevented pilots from exceeding limits. this was modified since the pilot is the best person to make that decision when his life is on the line. such intelligence often takes time to sort out.
while watching the videos i wondered how brakes were controlled and if brakes could be applied from the trailing unit, at least at first, presumably from obvious reasons?
and similarly if brakes could be released from the head unit? can brakes for any consist be independenly controlled, and for units in the middle of the train, can front and rear brake connections be independently controlled?
and with regard to power, why can’t the computer independently control power on various units to at least maintain a desired speed, if not acc/deceleration, or even coupler force?
Generally the brake application is applied from each of the remotely controlled engines at the same time in order to minimize the transmission time through the train line. The brakes need to be applied to the whole train ASAP to maximize the braking effort and reduce train line forces. If you apply brakes on the rear end first, then the chances of breaking the train in two is increased.
Why? That’ts what regular brakes do. The goal, once again is to release the brakes ASAP across the whole train.
The train line runs the length of the train. Any changes in pressure will be propogated throughout the the whole train line eventually. If you set or release the brakes on just part of the train you will end up with brake in twos or runaways.
RE: the sparky video of excessive wheelslip, that was probably caused by a defective wheelslip sensor or control module on that particular unit.
Here’s a TSB report on a runaway that happened as a result of poor train handling, but a key link in the chain was an emergency brake application that happened as a result of the safety features built into the Locotrol II system:
https://www.bst-tsb.gc.ca/eng/rapports-reports/rail/1996/r96c0086/r96c0086.html
I could be wrong here, and Mobilman44 should speak up and say so if I am.
But I took his question to simply mean MU’d diesels, not modern DP, and him wanting to understand how one engineer controls 2 or more locomotives without them fighting each other like our models sometimes do.
This question, if I am right, suggests that the OP does not fully understand how a diesel electric locomotive works, let alone how how three or four of them respond to one set of commands.
Maybe he needs to understand how the traction motors are connected to the wheels and the fact that a real locomotive will roll when pushed, while our models will not.
And how the traction motors are controlled electrically and how the diesel engine and the traction motors respond to the commands from the engineer.
Maybe he needs to first understand how the four or six traction motors are separately geared to their individual axles and how they work together to move the locomotive.
Then it will make more sense to him how one set of commands can control multiple locomotives with minimal “conflict” as all these separately powered axles apply power to move the train, differently from our models with one motor applying power thru worm gears that will not free wheel.
Again, I could be wrong, but I think the OP is asking a more simple question than most of you have been trying to answer.
And now the irony in this, I am DC modeler, and nearly every train on my layout is powered by more than one powered locomotive. And while many are relatively “matched sets”, I also run double or trippled headed steam of mixed brands and wheel arrangements.
Example, a Spectrum 2-6-6-2 and a Proto 2-8-8-2 on the head end of a coal drag of 40-45 hoppers. They run fine together, no modifications, nothing done to “speed match” them.
Generally, if you really need two or more locos, and the starting voltage and gearing is close, they will run fine together.
Cool. The CN uses 2 B&LE tunnel motors as helpers on Byron Hill, which is just south of Fond du lac, WI.
Mike.
Railroaders who operate 1:1 equipment but do not model would probably not understand his joke about matching locomotive speeds. Granted, you’d be unlikely to run into such a person on a forum like this.
I’ve seen that line a few times over the years in various places online, and I’ve even heard it in person out at the museum (along with “what kinda transmission’s in that thing”).
this is interesting.
i can understand that it may be ideal that brakes be applied to all cars simultaneously, but my understanding is this is impossile with current air brakes.
that brakes are applied to cars starting with the cars closest to the source that the brakes are released from. if there is a single consist at the front of the train, brakes get applied to the front of the train first resulting in “coupler slack (?)” being lost toward the rear of the train and the train “bunching up (?)” (i don’t know wat the proper terms are for these behaviors).
if there are engines at each end of the train, this means from each end and that braking occurs last to cars in the middle of the train. if there are engines in the middle of the train, it further “equalizes” the application of the brakes resulting in brakes being more evenly “applied to the whole train ASAP”.
as an (electrical) engineer i assume that being able to independently control power and braking at different parts of the train would improve control. i don’t assume a (locomotive) engineer would know what to do with this control, but assume a computer could. an engineer would tell the computer what he wanted to do and the computer would figure out how
i assume there are certain situtations where this would be most useful possibly going up/down a grade on a curve, cresting a hill or (??)
Geez Sheldon,
I do understand how a diesel loco works. I feel bad that my question exposed all that guessed at ignorance you dug up.
Others before you answered my question, and I guess I just marvel at how a consist of various different locos could pull/push together without fighting each other.
In the future, I’ll be a lot more selective of what questions I ask here. Ha, whoever said there was no such thing as a stupid question was obviously wrong.
Shame on me…
A modern EOT or end of train device will allow controlled or simultaneous brake pipe reductions from the rear, too. This type is in development but the current EOTs will allow an emergency application from the rear. No need for a locomotive to apply brakes from the rear.
Regards, Ed