How Long Does A Train Take To Stop

Member since
March 2002
9,265 posts

Posted by edblysard on Friday, Oct 28, 2005 four:31 PM

Busting it from the rear is a last ditch effort...
Information technology would have the effect of peachy the whip on the railroad train, with the locomotive at the terminate of the whip...guaranteed to interruption the train if the loads are on the caput end.
The engineer has to flip a switch on the head end device to blow it from the EOT...virtually sill use the railroad train restriction handle to plug it...
If you dump it from the head end, and zilch happens, or you're pretty sure they all didn't bosom, so you plug it from the rear.

Say a train breaks in half, the air sets upwardly from the break, and runs away from that separation...the cars closest to the break dumps, then the next, then the side by side, all in progression away from the break in both directions....

Dumping from both ends at the same fourth dimension would have the event of stretching the train in the middle, and get you a drawbar or a knuckle at least.

In a normal emergency application, the air exhaust from a big pipe under the cab, the railroad train line dumps from there, and the pressure drops on each car backwards from the locomotive...as it takes a fraction of a second for each brake valve to "sense" the drop in the train line from the machine ahead of information technology, then to trigger the brake valve, the longer the train, the longer the progression from the "break" be it in the cab via the restriction valve, or a separation in the train somewhere, and then the longer the train, the longer it takes.

Air density and temperature can have an effect too, the colder it is, the denser the air is, the longer information technology takes.

It's a simple, primitive arrangement, just information technology works, quite well, because it is so unproblematic.

That'southward the basics…I am certain someone volition jump in here with a super technical explanation, merely it really is uncomplicated.

Answer

Member since
January 2001
From: US
i,537 posts

Posted by jchnhtfd on Monday, October 31, 2005 10:47 AM

I practice retrieve the idea of mid-train devices has some merit. However, things need to be looked at in perspective. Suppose that nosotros have a x,000 pes long train , travelling at 60 mph, and suppose that, in addition, we take very practiced dry rail weather and all the cars are braked evenly at about maximum effort and a whole bunch of other goodies. Now... all that being so, information technology will take at to the lowest degree 55 seconds and about half a mile for that thing to stop in full emergency, once all the brakes are on. Whatsoever divergence from our supposed excellent conditions will make it take longer.

At present... if nosotros have directly air and no FRED, and assume no braking until all the brakes start to set upwardly, we take a fourth dimension of virtually 12 seconds, give or take, from when the engineer dumps it to when we start to stop; well-nigh an extra 1100 feet. Now that'south meaning. If nosotros apply FRED, and the engineer gets it and the chief valve at in one case, nosotros cut the time to 6 seconds and the altitude to almost 550 feet -- quite significant. Simply...

If nosotros add another FRED in the middle, nosotros only save 250 feet or and then and three seconds. Diminishing returns... Add together two more, splitting the train into quarters, and it'southward merely another 125. And then on.

Keep in mind that one of the big reasons for electropneumatics on rider equipment is not stopping distance, but passenger condolement from reduction in slack action...

Jamie