TGV rails are welded no click-clack nor Kodak
Ph
Le 4 juin 2014 à 17:16, Chris Trask <christrask@xxxxxxxxxxxxx> a écrit :
>>
>> One of the major causes of delay on the California Zephyr is "heat
>> restrictions" in the mountains. With higher temperatures, the rails
>> lose their lateral stiffness* and the trains have to stay under 20 MPH
>> (usually 15 MPH as they come down the eastern slope of the Rockies)
>> going around all the twists and turns.
>>
>> * Rails are welded together while they are heated up to a certain
>> temperature. This expands the rail segment being worked on. As it
>> cools, it shrinks and tightens up. In the wintertime, the rails
>> continue to shrink a bit and can pull sideways off the railbed in the
>> mountains. In the summertime, at a certain temperature, the tightness
>> is gone and the rails are neutralized. Above that temperature, they
>> become looser and you'll get lots of wavies. This is why rails can be
>> welded together without expansion joints--they are preheated to the
>> expanded length at time of welding. A broken rail, that is under
>> tension can do scary stuff to anything surrounding it.
>>
>
> There was a major derailment years ago in Florida where the welded rails
> had warped. You will probably never hear of such a problem in Europe, where
> the ends of the rails are chamfered, allowing for the expansion and
> contraction over temperature. This is why you do not hear the characteristic
> "click-clack" of US trackage. I think that Southern Railway adopted this
> design. My understanding is that the chamfered end design originated in
> Germany.
>
>
> Chris
>
> When the going gets weird, the weird turn pro
> - Hunter S. Thompson
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