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The Mechanics Of Polar Express' Ice Drifting


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Ok I love the Polar Express. So after watching these: https://m.youtube.com/watch?v=l_3Nhbn1Mx8 https://m.youtube.com/watch?v=COdoHpU_a8U 999999999 times, and because I have quite some knowledge in locomotives I wanted to express my thoughts.

In the movie all the engineer seems to be doing is constantly pulling and and pushing the regulator,  throttle, and the brake (idk if it's the independent or train, probably independent though considering the way the train moves). The locomotive though appears to be doing much more. First of all, SOMEHOW, the wheels appear to be able to operate in one direction, while the other side goes in the opposite direction! (Again based on my observations) Besides this, if the ice doesn't break under the weight, and if the couplers don't snap (and if the bogeys co-operate) then this seems actually possible! Though I guess it's entirely possible that the 2-8-4 has some sort of custom made extra reverser lever, with a lock mechanism.

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Thoughts?

 

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2 hours ago, cubinator said:

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It's a magic train with a ghost on the roof. It wasn't not going to make it.

Well, I did read somewhere that some locomotives had a control that could vary thrust on each cylinder, different from the other, to help get around curves. 

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The video is a mashup, not chronological and some cuts are even mirrored, so all bets are off concerning the realism.

That being said, I haven't noticed the inconsistencies in the wheel turning direction. Care to point out the time stamp?

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Maybe the sheer weight of the train would help the wheels cut into the ice and make virtual "tracks" wherever it goes? They still have a very big problem and probably will not go to space today, except that it's a magical train with a ghost on the roof.

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Well if we used an articulated design such as a Union Pacific Big Boy we could have a set of hydraulics push the front detached section of drive wheels to either direction to help with steering but it would probably just start drifting and end up with something like this:

 

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20 hours ago, Shpaget said:

The video is a mashup, not chronological and some cuts are even mirrored, so all bets are off concerning the realism.

That being said, I haven't noticed the inconsistencies in the wheel turning direction. Care to point out the time stamp?

I've watched the actual Polar Express many times, it's just these videos sparked my interest that little bit more. You never actually see the other wheels in reverse, but considering the motions the train makes, its kinda implied. (Also the engineer is constantly throwing the reverser back and forth so...) The weird thing is, in the movie we almost always see the right side of the locomotive...(or left from viewing it from the front)

18 hours ago, cubinator said:

Maybe the sheer weight of the train would help the wheels cut into the ice and make virtual "tracks" wherever it goes? They still have a very big problem and probably will not go to space today, except that it's a magical train with a ghost on the roof.

You can see the wheel marks in videos and the movie, but they're not that deep... 

Actually, I already have a locomotive on the Mun. Yet to send some traincars though.

Edited by Spacetraindriver
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With all that stress, the couplers would snap and the Pullman cars would separate from the locomotive. Also, the tender would probably lose some coal because of all the sharp turns. I don't think an 802,500 pound locomotive would have made it through ice, let alone the FULLY loaded pullmans, which are heavy already. When you add passengers, it increses the weight by approximately one third. If you want the actual numbers, here you go: 79 TONS.

The entire movie is scientifficly inaccurate. For instance, when the train goes down  the.... I think it was the 90% grade, They would have probably died. Trains in the US usually have a 3% grade limit, unless they are logging trains, like shays. The pure G-force from the decent would probably make them black out, and with all that momentum, instead of leveling out on the track at the bottom, they would have smashed into it and the train would be history.

 

Those are my thoughts. Do you agree?

Edited by Lo Var Lachland
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  • 2 years later...

GUYS! I FIGURED IT OUT!

Most engines, 1225 included, had sanders to lay down sand for each side of the wheels, you could sand each side INDIVIDUALLY.

At first, the dude uses the inertia to turn around, but turns using inertia and sanding, therefore "drifting" the train.

Also, clearly, at the end, when they're going up the grade, he's out of sand, as evidenced by the extreme wheelslip

Edited by KerbalsAreKute
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On 1/28/2017 at 10:33 PM, Lo Var Lachland said:

Trains in the US usually have a 3% grade limit, unless they are logging trains, like shays.

The limit has more to do with adhesion than with G-force. Don't want to slip either way around.

4 hours ago, KerbalsAreKute said:

... you could sand each side INDIVIDUALLY.

Interesting to brought this up, wouldn't have thought of it otherwise.

 

 

Then again, it is a film, and a magical one at that (I mean, it just went through a neighborhood's road at the start, which is... quite the work to do).

Edited by YNM
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On 1/24/2017 at 1:58 PM, Spacetraindriver said:

Besides this, if the ice doesn't break under the weight

I'm pretty sure in the early days of the Trans Siberian tracks were laid across the ice on Lake Baikal in winter--either it shortened the journey around Baikal or the route around the lake had not been cleared yet.  I think I heard this in a Russian history class (or maybe when I was in living in Russia 20 years ago), but I cannot remember. A quick Google search is only turning up heaps of tourism pages, but I am almost 100% certain that was the case.

Edited by Klapaucius
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17 hours ago, Klapaucius said:

in the early days of the Trans Siberian tracks were laid across the ice on Lake Baikal in winter

Yes, but no steel wheels right on ice, it'd just break instantly. The sleepers and rails help to spread the weight.

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30 minutes ago, YNM said:

Yes, but no steel wheels right on ice, it'd just break instantly. The sleepers and rails help to spread the weight.

True, but I wonder if it is still possible even without the rails. Ice on Baikal gets to 6 feet thick, and of course, it is floating, so is well supported.  I wonder what the breaking point is?  Almost certainly, it would carve massive grooves, but would the ice hold?

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12 minutes ago, Klapaucius said:

I wonder what the breaking point is?  Almost certainly, it would carve massive grooves, but would the ice hold?

I think it'd be like ice skating, but massively overscaled. Not sure, never done one myself... I haven't even witnessed snow !

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  • 4 weeks later...
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