Air Train

[NadCixelsyd]

I had to change planes at JFK which gave me a ride on the AirTrain.
OK, there are running rails and a 3rd rail for power. Situated
between the running rails is a metallic thingy about 10 inches wide.
It appears to be everywhere except for a few feet when it would cross
one of the running rails (like at a switch/crossover).

Is this thingy above, below, or at, the height of the running rail.
What is its purpose (current return?)

[Michael Finfer]

Stephen Furley wrote:
>
>
> On 28/4/09 19:47, in article
> 58a170cc-4859-4372-8f75-287d91a5dee4...oglegro********,
> "NadCixelsyd" <nadcixelsyd@********> wrote:
>
>> I had to change planes at JFK which gave me a ride on the AirTrain.
>> OK, there are running rails and a 3rd rail for power. Situated
>> between the running rails is a metallic thingy about 10 inches wide.
>> It appears to be everywhere except for a few feet when it would cross
>> one of the running rails (like at a switch/crossover).
>>
>> Is this thingy above, below, or at, the height of the running rail.
>> What is its purpose (current return?)
>
> I've no idea as to the height of it, but the JFK Airtrain is driven by a
> linear induction motor, and it sounds like you're describing a reaction
> member against which the motor magnetically 'pushes', so to speak.
>
I got in there on a tour before the line opened, and that was the
explanation.

Michael Finfer
Bridgewater, NJ

[NadCixelsyd]

On Apr 28, 3:48*pm, Stephen Furley <aoo...@dsl.pipex.com> wrote:
> On 28/4/09 19:47, in article
> 58a170cc-4859-4372-8f75-287d91a5d...@q33g2000pra.************.com,
>
> "NadCixelsyd" <nadcixel...@********> wrote:
> > I had to change planes at JFK which gave me a ride on the AirTrain.
> > OK, there are running rails and a 3rd rail for power. *Situated
> > between the running rails is a metallic thingy about 10 inches wide.
> > It appears to be everywhere except for a few feet when it would cross
> > one of the running rails (like at a switch/crossover).
>
> > Is this thingy above, below, or at, the height of the running rail.
> > What is its purpose (current return?)
>
> I've no idea as to the height of it, but the JFK Airtrain is driven by a
> linear induction motor, and it sounds like you're describing a reaction
> member against which the motor magnetically 'pushes', so to speak.

Ahhh, makes sense. From inside the train, the thingy, as I called it,
looked to be less than an inch below the running rails.

Now, what's the advantage of linear induction v. putting motors in the
cars? It sounds more expensive.

[SMS]

danny burstein wrote:

> (speaking of which, it says the electrical standard
> for the more traditional Swedish trains is 16,000 VAC,
> which makes sense, but... also it's at 16.6 hz. Huh?)

It's based on 1/60th of the old 16 2/3 rpm phonograph records

[Phil Kane]

On Thu, 30 Apr 2009 01:47:56 -0500, Stephen Sprunk
<stephen@sprunk.org> wrote:

>16 2/3Hz is one third of 50Hz, the standard mains frequency in Europe
>(and much of the rest of the world). While it seems a strange number,
>it is common for 15kV railroad electrification in Austria, Germany,
>Norway, Sweden, and Switzerland. 50/60Hz is more common for systems at
>25kV.

Transformers operating at 16+ Hz (or at the Pennsy's "standard" 25 Hz)
take a LOT more iron than those operating at 50/60 Hz. I wouldn't
doubt that the dead weight of the transformer on the GG-1 was a major
part of the engine's weight aiding in traction.

The aircraft industry adopted 400 Hz before WW-II to cut down on the
iron necessary in flying machines.
--

"Stand Clear of the Closing Doors, Please"

Phil Kane - Beaverton, OR
PNW Beburg MP 28.0 - OE District