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Old February 24th, 2009, 05:03 PM   #1
iloveshinkansen
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MISC | Good point and Bad point between EMU and Locomotive-pull train

What are good points and bad points. Why TGV are built in locomotive-pull style. On the other hand, the Japanese bullet train are built in Electric Multiple Unit? and what kind of them do you think the most efficient?
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Old February 24th, 2009, 07:34 PM   #2
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The advantage of power cars (such as used in TGV, ICE 1 & 2) is that if there is a problem with the traction system it can easily be fixed through changing the power car, while the rest of the train is still operational. Some highspeed trains like railjet even use a modified locomotive for that purpose. In addition middle cars are lighter and can easily be disposed or even taken out for maintenance and other reasons. In terms of passenger comfort push-pull-style trainsets are usually better, as they tend to have less vibrations and noise stemming from the engines in the passenger section (just compare ICE1 and ICE3).

The advantage of EMUs is that traction is distributed all over the train, hence the traction power acts upon several axes all over the train, rather than just at the beginng and/or end of the train. As a result EMUs usually have better acceleration.

In the end both systems have pros and cons and it's hard to declare a winner in the game. Currently EMUs seem to have come into fashion over the past few years, but that doesn't have to say much.
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Old February 24th, 2009, 07:58 PM   #3
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Each concept has advantages / disadvantages:

TGV (TGV Atalntique, 485 seats, length 240 m, 300 km/h): The train has 8 traction motors. The power equipment is located in the two end cars.
Maintenance is easy since all the equipment is accessible from an aisle thru the machine room of the power head.
Max. axle load of the train: 17 t.

Shinkansen (N700, 1323 seats, length 404 m, Vmax: 300 km/h): The train has 56 traction motors.
The power equipment is distributed over the train. Traction equipment is placed under the floor or in cubicle near the entrance.
Maintenance is difficult since there are mor parts to be maintained which are located in areas with difficult access.
Max. axle load of the train: 10 t => less stress on tracks => higher speeds in curve

TGV has less parts and can be easier maintained, but stresses the tracks more.
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Old February 24th, 2009, 08:08 PM   #4
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If I'm not mistaken Shinkansens maximum axle load is at least 14 tonnes, the empty weight is slightly more than 10 tonnes per axle on the lightest cars... Anyways, Emu's are more efficient trains, I think locomotives will soon be obsolete in terms of passenger travel.
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Old February 24th, 2009, 08:21 PM   #5
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Quote:
Originally Posted by Jay View Post
If I'm not mistaken Shinkansens maximum axle load is at least 14 tonnes, the empty weight is slightly more than 10 tonnes per axle on the lightest cars... Anyways, Emu's are more efficient trains, I think locomotives will soon be obsolete in terms of passenger travel.
I seriously doubt that. The majority of all trains are still classic push-pull-trains and it will take several decades to replace all that.
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Old February 24th, 2009, 08:29 PM   #6
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EMUs also tend to be more efficient when it comes to seats, since they don't have seatless powercars.

The main reason why the TGV has powered motor cars is the articulated design of the passenger cars that was chosen for the following reasons:
- less bogies, reducing the weight
- a lower body for better access at low platforms.
- no seats above the bogies, increasing the comfort.

Another reason for the power cars was the use of body mounted traction motors instead of bogie mounted traction motors. This is already difficult in non articulated EMUs so it was impossible to build those in the passenger cars of the TGV.
The Shinkansen 0 had much less design restrictions, using the much bigger loading gauge and only for use on the purpose build high speed tracks it they could go with an EMU design making it very light.
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Old February 24th, 2009, 08:40 PM   #7
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Quote:
Originally Posted by Momo1435 View Post
EMUs also tend to be more efficient when it comes to seats, since they don't have seatless powercars.
This argument is silly, as most modern highspeed trains are composed of so called half-trains with 7 passenger cars + traction (in case of push-pull trains). So there is no difference in that regard. In contrast, classic push-pull trains (loco + cars) tend to be much longer than single EMUs (which are often used in double traction on busy routes).
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Old February 24th, 2009, 08:42 PM   #8
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Quote:
Originally Posted by rheintram View Post
In terms of passenger comfort push-pull-style trainsets are usually better, as they tend to have less vibrations and noise stemming from the engines in the passenger section (just compare ICE1 and ICE3).
I've rarely felt anything but silky smooth acceleration on a Shinkansen.

I have felt vibration on French intercity trains though.

I can't speak for ICE3 vs. ICE1, but it would seem to me that vibration is more a matter of how the train is built and track qualtiy than EMU vs. Locomotive. However, this is purely anecdotal evidence from the recesses of a hazy memory.

The successor to the TGV, the AGV, is I believe, also an EMU design.
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Old February 24th, 2009, 09:05 PM   #9
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The AGV is an articulated EMU with powered articulated bogies.

Quote:
Originally Posted by rheintram View Post
This argument is silly, as most modern highspeed trains are composed of so called half-trains with 7 passenger cars + traction (in case of push-pull trains). So there is no difference in that regard. In contrast, classic push-pull trains (loco + cars) tend to be much longer than single EMUs (which are often used in double traction on busy routes).
As silly as it is, it's used as an actual argument since it's given as one of the advantages of the AGV over the TGV.

And to be honest, I think it's a valid argument.

look

ICE 2 vs. ICE 3

half-train vs. EMU

391 seats vs. 460

That's 70 seats more in the ICE 3 trains that has the same length of 200 meters but a seat capacity that's 18% higher.
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Old February 24th, 2009, 10:04 PM   #10
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Eurotrain: ICE2 power car + TGV Duplex Cars = the beauty of push-pull systems

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Old February 24th, 2009, 11:07 PM   #11
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And the best thing about it was that the Taiwanese Railways bought Shinkansen EMU's even after the Eurotrain was declared the preferred bidder.

[IMG]http://i44.************/99mcyb.jpg[/IMG]

And if Alstom can build the double deck AGV it will be the death of push-pull high speed trains. Then France can also buy it's High Speed EMUs just like Japan, Germany, China and Russia just to name some countries.
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Old February 25th, 2009, 04:57 AM   #12
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I hope you all realize that one of the biggest motivations of building multiple-units (I hope you will all stop using EMU as the universal word for multiple-powered trains, because there are diesel versions as well) is that it is much harder to build one extremely powerful engine as opposed to building a number of smaller less powerful ones.

There are many very true adventages to the push/pull system. Some of the the most important are the flexibility presented by the abilities to freely couple/de-couple wagons and the abilities to replace broken down engines. Where as to change the number of cars coupled to a multiple-unit will require a complete reprograming of the train's systems. For example, if you have an 8 car train but the demand calls for 2 extra cars, you will not beable to couple two more coaches onto the existing 8 car unit. To satisfy demand, you will most likely have to couple another full 8 unit train set and run the train with 6 units empty. Although the possibility of coupling two full sets of multiple-units together always exist, but it still doesn't provide the economic effeciency of adding or subtracting only one of two wagons at a time depending on need.

Also, multiple units have much more moving parts and as logic assumes, require more maintinence and have a greater chance of breaking down.


China went multiple units because it failed, after years of trying and many prototypes built, to successfully construct a single populsion push/pull high speed train system capable of meeting the required standards to prerform full-scale operational service.




This is one of the prototypes

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Old February 25th, 2009, 05:04 AM   #13
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Everyone knows there are diesel versions, they're referred to as DMU's. The OP compared Shinkansen (electric) with TGV (electric) so that's why most people started referring to EMU's rather than bringing diesel into the equation.

The majority of passenger rail in developed countries (outside of North America and the UK) is handled by electric trains rather than diesel.
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Old February 25th, 2009, 06:46 AM   #14
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Although some might have caught the debate in another thread between myself and another member (with idiotic claims that TGV is an EMU).
It's really simple push-pulls are less costly in both initial and maintenace and replacement is alot simpler than EMU when the is a malfunction to a motor.
On the other hand EMU have a lower acceleration rates and higher maximum axle load on a single axle(loco axle) making construction cost a bit higher for tracks.

As for efficiency, as rule of thumb, with more electronic circuitry the greater the loss in power input due to resistance.
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Old February 25th, 2009, 07:07 AM   #15
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In my opinion...I think power cars are cheaper to manitan in long run and it's more simpler, but doesn't do as well as EMU at high speeds, but I could be wrong. I think EMU is "disposable" type of trains which if you want to use a duplex railcars, you can't do that with a EMU.

I like the new AGV which is a EMU which will top around 220 mph. I think EMU is the future, but I was amazed how many traction motors a EMU would have compared to the power cars.
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Old February 25th, 2009, 07:12 AM   #16
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Quote:
Originally Posted by sequoias View Post
In my opinion...I think power cars are cheaper to manitan in long run and it's more simpler, but doesn't do as well as EMU at high speeds, but I could be wrong. I think EMU is "disposable" type of trains which if you want to use a duplex railcars, you can't do that with a EMU.

I like the new AGV which is a EMU which will top around 220 mph. I think EMU is the future, but I was amazed how many traction motors a EMU would have compared to the power cars.
Actually less motors equate to faster speed because there is less magnetic resistance.
An electric motor creates a magnetic drag, with more motors there is more drag making loco with the same power output faster.
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Old February 25th, 2009, 07:23 AM   #17
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From what I read on this thread, they say that EMU is slower to accelerate than a power car pulling/pushing the railcars.
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Old February 25th, 2009, 07:29 AM   #18
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Quote:
Originally Posted by sequoias View Post
From what I read on this thread, they say that EMU is slower to accelerate than a power car pulling/pushing the railcars.
It's the otherway around.
Less axle load per powered axle means larger power band with less possibility of powerslips between steel track and wheel.

The train with fastest acceleration rate is the Shinkansen N700 series which most of it's axles are powered.
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Old February 25th, 2009, 07:40 AM   #19
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Quote:
Originally Posted by Tri-ring View Post
It's the otherway around.
Less axle load per powered axle means larger power band with less possibility of powerslips between steel track and wheel.

The train with fastest acceleration rate is the Shinkansen N700 series which most of it's axles are powered.
Makes sense... What's the acceleration rate of the Shinkansen N700?

The average diesel commuter train here in the US has acceleration rate of around 1.6 miles per hour per sec.
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Old February 25th, 2009, 07:46 AM   #20
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Quote:
Originally Posted by sequoias View Post
Makes sense... What's the acceleration rate of the Shinkansen N700?

The average diesel commuter train here in the US has acceleration rate of around 1.6 miles per hour per sec.
2.6km/h/s (commercial acceleration rate not necessarily the maximum accerleration rate)
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