Legit #trains #railroad #locomotive questions:
This morning I drove by a locomotive pushing the back of what I presume was a fairly long freight train and it was just dreadfully (read: extremely beautifully) noisy, like it was working at full effort.
1) Is this true, in terms of like the physics of railroads
2) do railroads observe any like difference in maintenance needs of locomotives that end up at the back of the train a lot or is there like a plan to avoid this?
@coryw Diesel Engines are designed to either pull/push. So if the engine was having issues, it needed to go into the shop, not because it was pushing.
It didn't sound like issues per se, it sounded like it was going at full bore. I presumed that there was some kind of physics involved in why the one engine at the back sounds like it's working a lot harder than the five up front, which is also to say that this is a consistent phenomenon and I've noticed it in a few different scenarios.
I guess my question was, if an engine ends up at the back a lot and consequently runs at max all the time, does that have a noticeable impact
@fuzzface
or: do the railroads intentionally manage where they're placed so you don't have one particular unit ending up at the back all the time as their way of managing that particular maintenance need, if it's even there.
But yeah, I realize that it's not strictly speaking a technical issue to run 'backward' or anything (this one was actually facing 'forward' anyway, I should have added that so that's my bad.)
@coryw I do not know enough to answer you properly. I do know that some railroads use helper engines at steep grades, and I believe they remain on site to assist the next through train.
@coryw Pushers sometimes ensure that the force on the train is uniform. There was a bad accident in Dunsmuir, CA many years ago where a train without a pusher derailed on a tight uphill curve. The pullers literally pulled the train off the track in the middle of the consist on the curve. Dumped a lot of fertilizer in the water, killed everything downstream. See Wikipedia for Southern Pacific RR - July 14, 1991
@coryw Finally, if you look at the travels of your average engine they appear to remain in one place for local work, or are nomads. Generally the patterns are only known internally at the RR. My apologies for not being able to give you a clearer answer.
No problem! It's interesting to think about at least.
I know that slack is a problem and I think most of the longest trains (again: bnsf transcon, I live near the ARizona divide, and then they go down to alburquerque and then back up to denver before crossing Kansas on the way to Chicago) have middle engines and some of the most heavy ones have back engines as well.
@fuzzface
There might be more helper engines somewhere, but also I think the line is busy enough the railroad just runs them through, at least from Barstow, CA to somewhere east of Denver.
If I had to guess, they just rearrange the engines randomly enough between jobs they don't differentiate, but it would be interesting to hear for sure.
I know BNSF specifically is particular enough to almost never run EMD on the transcon, for example.
notes:
- This was in the USA
- The locomotive was an SD70ACe.
- I notice this with dash9s and evolutions too
- also I think it's the first time I'd really heard an SD70
- I live along the BNSF transcon and so I almost never see anything but GEs so it was very exciting
- I don't remember if it was an ACe or an T4, but I presume the principle would be the same since it's probably Physics(TM) causing this phenomenon.