Basic question about EMUs

[scott]

First off, I have to admit that this question reveals stunning ignorance on my part, especially given my (largely joking) extreme preference for electrics over diesels. But I'm not an engineer or anything close, just a generally clueless person who likes to travel by train.

 

Anyway--I had always assumed that, in electric locomotives and EMUs, there was only one gear ratio between the motors and the drive wheels. But often I've heard what *sounded* like a multi-ratio transmission shifting when an EMU or subway train accelerates or slow down. Plus I was just reading harukablue's thread about DMU transmissions. So--do some EMUs have the same sort of multi-ratio transmission, or is what I'm hearing just the result of some electrical operation?

[harukablue]

I think its the thrystor control?,,,not sure about Japanese units but here in the UK the class 323 is the most prominant.

 

 

As for Locos the Siemens Taurus will entertain you with sweet music.

 

[scott]

Interesting--those aren't quite the same sounds.

 

One example--the arriving DC Metro train in this video"

 

[marknewton]

I'm not aware of any EMU with multiple-ratio transmissions. The Washington video just sounds like gear and regen braking noise to me.

 

Cheers,

 

Mark.

[bikkuri bahn]

Electric motors don't have transmissions, that's why they have tremendous torque compared to internal combustion-based setups.  The sound you hear is the electrical equipment, namely the VVVF inverters- they often have a stepped sound output, especially on the older GTO equipped packages.  They have even been tuned to make distinctive sounds, such as Siemens' produced equipment.

[Mudkip Orange]

One example--the arriving DC Metro train in this video"

Don't you love the way those trains sound? Nice door chimes too.

[Nick_Burman]

Electric motors don't have transmissions, that's why they have tremendous torque compared to internal combustion-based setups.  The sound you hear is the electrical equipment, namely the VVVF inverters- they often have a stepped sound output, especially on the older GTO equipped packages.  They have even been tuned to make distinctive sounds, such as Siemens' produced equipment.

 

Older all-DC drive trains had series, series-parallel, parallel and "shunt" positions in the switchgear equipment. Sometimes when moving from one position to the other there would be a short pause or reduction in the power feed while the switchgear sorted itself out. After this happened the train would continue motoring until the next changeover. This happened to protect the relays from erosion by arcing. For a passenger this would translate into a short period when the train would stop accelerating, then continue a few seconds later, as if the engineer was "shifting gears".

 

Older diesels do the same thing (especially ALCOs) - I remember riding a passenger train in India behind a DLW WDM-2 or -3, every time the loco went into transition the loco's engine would drop revs with the characteristic ALCO fweeeeee and the train would bunch up for an instant. As soon as the loco finished transitioning, up came the lovely 251 grumble and out ran the slack on the train. You always could know what the engineer was doing by feeling this backwards and forwards movement.

 

 

Cheers NB

[ToniBabelony]

Just to add a Japanese SIEMENS example to the list:

 

[scott]

I'm not aware of any EMU with multiple-ratio transmissions. The Washington video just sounds like gear and regen braking noise to me.

 

Electric motors don't have transmissions, that's why they have tremendous torque compared to internal combustion-based setups.  The sound you hear is the electrical equipment, namely the VVVF inverters- they often have a stepped sound output, especially on the older GTO equipped packages.  They have even been tuned to make distinctive sounds, such as Siemens' produced equipment.

 

OK -- thanks for setting me straight. I didn't *think* they had transmissions, but couldn't account for what I was hearing.

[bikkuri bahn]

Here are some JR Tokai 313 series with more recent IGBT inverters, more low key & smooth than the old GTOs. I'm not sure which station this is, perhaps the Nagoya hands here can pinpoint it.

 

http://www.youtube.com/watch?v=hRBlZHR8mYY

[Tecchan]

The Taurus noise is absolutely amazing!

It looks like science fiction! 

[The_Ghan]

Electric motors don't have transmissions, that's why they have tremendous torque compared to internal combustion-based setups.  The sound you hear is the electrical equipment, namely the VVVF inverters- they often have a stepped sound output, especially on the older GTO equipped packages.  They have even been tuned to make distinctive sounds, such as Siemens' produced equipment.

 

Older all-DC drive trains had series, series-parallel, parallel and "shunt" positions in the switchgear equipment. Sometimes when moving from one position to the other there would be a short pause or reduction in the power feed while the switchgear sorted itself out. After this happened the train would continue motoring until the next changeover. This happened to protect the relays from erosion by arcing. For a passenger this would translate into a short period when the train would stop accelerating, then continue a few seconds later, as if the engineer was "shifting gears".

 

Older diesels do the same thing (especially ALCOs) - I remember riding a passenger train in India behind a DLW WDM-2 or -3, every time the loco went into transition the loco's engine would drop revs with the characteristic ALCO fweeeeee and the train would bunch up for an instant. As soon as the loco finished transitioning, up came the lovely 251 grumble and out ran the slack on the train. You always could know what the engineer was doing by feeling this backwards and forwards movement.

 

 

Cheers NB

 

Nick,

 

I find this very interesting.  Being a visual person, can you direct me to any explanatory notes and diagrams on the web so that I can better understand how EMU switch gear works?

 

Cheers

 

The_Ghan

[bikkuri bahn]

You may find these sites helpful:

http://www.jrtr.net/jrtr17/pdf/f40_technology.pdf

 

http://www.railway-technical.com/tract-02.shtml

[westfalen]

The Taurus noise is absolutely amazing!

It looks like science fiction! 

If I hadn't spent an afternoon at Innsbruck watching them myself in 2008 I would have said the video sound track was doctored.

[The_Ghan]

Thanks Bikkuri.

[miyakoji]

Isn't the Siemens control system in the Keikyu trains referred to as "doremifaa motor" or something?  The band Kururi worked it into their song Akai Densha (Red Train).  Looks like youtube took that video down.