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Old December 27th, 2011, 05:38 PM   #941
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Quote:
Originally Posted by Ariel74 View Post
A thing of beauty. It't a pity that the current railway ministry, a puppet of the oil/airplane industries, will probably not allow it to have test runs on their best tracks....
which country did you mention?
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Old December 27th, 2011, 06:06 PM   #942
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Quote:
Originally Posted by elianzoom View Post
I think that there are technical and phisical limits to the speed on conventional rail tracks, the test limit could reach up to 500 km/h but the commercial daily use it could be at 350 km/h, surpassing these limits increase the cost of the energy to move the train to that level that makes no sense in terms of getting any proffit. Concorde was really fast but was also non sustainable way of move people, only few ones could pay the cost.
This all depends on technological level. It may not be profitable now but can be very profitable/desirable in 20 years.
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Old December 27th, 2011, 06:45 PM   #943
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It's interesting that they still do research in faster bullet trains while having trains designed for up to 420km/h (e.g. CRH380BL) and let them run with a 300km/h due to "safety" and -more important - economic issues.
Beside this it is said that they plan to order lots of lower-speed-trains (around 250km/h) for transport - a reasonable (economic) decision for people travelling.
The one way or another: With a 6-car-train having more traction power then a 16-car CRH380 it's no wonder to become fast. How fast tests will show. And how long maintenace of track will take after test ((inofficial) test of modified 12-car CRH380BL at 487km/h should have taken 3 days of maintenace). And what will happen to the train afterwards (somebody has seen any CIT400 recently?).
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Old December 27th, 2011, 06:57 PM   #944
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Quote:
Originally Posted by elianzoom View Post
I think that there are technical and phisical limits to the speed on conventional rail tracks, the test limit could reach up to 500 km/h but the commercial daily use it could be at 350 km/h, surpassing these limits increase the cost of the energy to move the train to that level that makes no sense in terms of getting any proffit. Concorde was really fast but was also non sustainable way of move people, only few ones could pay the cost.
Good observation. For the last 30-40 years we have had an speed that are consistent with economic in air and rail -travel.
On the other hand, if a country can be an exception, I don't doubt it will be China.
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Old December 27th, 2011, 11:25 PM   #945
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Old December 27th, 2011, 11:46 PM   #946
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Quote:
Originally Posted by elianzoom View Post
I think that there are technical and phisical limits to the speed on conventional rail tracks, the test limit could reach up to 500 km/h but the commercial daily use it could be at 350 km/h, surpassing these limits increase the cost of the energy to move the train to that level that makes no sense in terms of getting any proffit. Concorde was really fast but was also non sustainable way of move people, only few ones could pay the cost.
You are right about the economics of running extremely fast trains. That's why we probably will never see those record breaking trains be put into commercial service in China. They are, after all, built as record breakers. Similar to the V150, X-15, or Formula One, their purpose is to push the limit of technology and stimulate innovation. Eventually technologies developed through these record breaking efforts will trickle down to our everyday life, and that's why while those machines are not practical, they are essential.
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Old December 28th, 2011, 02:42 AM   #947
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Does anyone know why Chinese trains don't have the bogie setup that French TGV's have, where two train cars are connected on a shared bogie?
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Old December 28th, 2011, 02:58 AM   #948
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Quote:
Originally Posted by Silly_Walks View Post
Does anyone know why Chinese trains don't have the bogie setup that French TGV's have, where two train cars are connected on a shared bogie?
They're called Jacobs bogies. They tend to increase axle loads which isn't quite favourable at high speed.
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Old December 28th, 2011, 03:28 AM   #949
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They're called Jacobs bogies. They tend to increase axle loads which isn't quite favourable at high speed.
I believe it is a little more complicated.
The trade off for jacobs boogies requires the cars to be much shorter then conventional boogie cars so a trainset will require more cars to provide the same amount of seats in which will require more material equating to more cost and weight in total.
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Old December 28th, 2011, 03:50 AM   #950
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Quote:
Originally Posted by Silly_Walks View Post
Does anyone know why Chinese trains don't have the bogie setup that French TGV's have, where two train cars are connected on a shared bogie?
I think question should be asked other way around because, I believe, TGV is the only high speed train set which uses this bogie type.

And, yes although it is more complicated, the main reason is axle load. Think an 8 car set, if it uses traditional bogies, it will have 16 of them but if it uses jacobs bogies it will only have 9 of them. This will increase axle load and since you have larger distances between bogies, cars need to be build more rigid which will increase weight.
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Old December 28th, 2011, 05:41 AM   #951
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Quote:
Originally Posted by foxmulder

This all depends on technological level. It may not be profitable now but can be very profitable/desirable in 20 years.
No air drag in 20 years?
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Old December 28th, 2011, 05:46 AM   #952
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Quote:
Originally Posted by SamuraiBlue

I believe it is a little more complicated.
The trade off for jacobs boogies requires the cars to be much shorter then conventional boogie cars so a trainset will require more cars to provide the same amount of seats in which will require more material equating to more cost and weight in total.
But on the other hand it's way safer and increases travel comfort. By nowadys technologies, too much weight is actually not a real argument anymore. The French made it decades ago.
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Old December 28th, 2011, 06:32 AM   #953
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Quote:
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But on the other hand it's way safer and increases travel comfort. By nowadys technologies, too much weight is actually not a real argument anymore. The French made it decades ago.
I do not know where you got that notion since weight(mass) and energy consumption is directly linked which even Alstom recognizes.

Last edited by SamuraiBlue; December 28th, 2011 at 09:26 AM.
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Old December 28th, 2011, 07:18 AM   #954
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I could be wrong but is passenger comfort really an advantage of Jacobs Boogies? My two trips between Paris and Marseilles on board a TGV running at 300km/h is my worst HSR experience ever. ICE 3 ride in German, E2 ride in Japan, and all series of CRH rides in China felt in a completely different class.

I think Samurai is right about the size of each car is limited, so to achieve the same seating capacity as a 380AL with the same number of cars the only way is follow TGV Duplex' design. Otherwise you'll have to increase the number of cars of the trainset. Eitherway the total weight of the trainset will be increased, and more powerful motors are needed, the entire drivetrain becomes heavier, etc.

Last edited by hmmwv; December 28th, 2011 at 07:28 AM.
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Old December 28th, 2011, 07:24 AM   #955
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Quote:
Originally Posted by KingNick View Post
No air drag in 20 years?
Quote:
Originally Posted by KingNick View Post
But on the other hand it's way safer and increases travel comfort. By nowadys technologies, too much weight is actually not a real argument anymore. The French made it decades ago.
No weight anymore after 20 years?
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Old December 28th, 2011, 02:01 PM   #956
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Materials can be substituted with less heavy compositions. How do you do it with air drag? Vacuum Tunnels?
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Old December 29th, 2011, 12:45 AM   #957
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You have completely missed the point, if the weight issue can be overcome with technology, then it's premature to claim that air drag cannot be overcome with technology in 20 years. Remember the whole point was about whether higher speed trains can be economical, maybe propulsion technology can be advanced enough in the near future so that powering trains at 600km/h is no longer a problem at all.
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Old December 29th, 2011, 02:04 AM   #958
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Rumors say CRH500 has air brakes.
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Old December 29th, 2011, 03:48 AM   #959
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Quote:
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Rumors say CRH500 has air brakes.
The Fastech 360 had those too, I wonder why they chose not to use them on the E5
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Old December 29th, 2011, 07:09 AM   #960
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Quote:
Originally Posted by hmmwv
You have completely missed the point, if the weight issue can be overcome with technology, then it's premature to claim that air drag cannot be overcome with technology in 20 years. Remember the whole point was about whether higher speed trains can be economical, maybe propulsion technology can be advanced enough in the near future so that powering trains at 600km/h is no longer a problem at all.
Not even 350 is really economical these days. Air drag squares with increasing speed and its not the question if you can create enough power for such speed, but the energy consumption. You have to gain an almost unreal increase in efficiency to be as economical as we are nowadys with 200-250. Plus there are many more problems (contact wire, traction...) going hand in hand with increasing speed.
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