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| Air Brakes/BIE Question (697609) | |
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| (697613) | |
Re: Air Brakes/BIE Question |
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Posted by BLE-NIMX on Sat Oct 25 00:13:40 2008, in response to Air Brakes/BIE Question, posted by gbs on Fri Oct 24 23:56:25 2008. I assume you meant SMEE type straight air systems so here it goes in short. For a train to be able to release its brakes the brake pipe must be charged. On SMEE cars, when that happens, an emergency port closes and seals off the main reservoir from the brake cylinders, a control pipe or straight air pipe takes over charging and releasing the brake cylinders, the emergency contactor closes and allows electric brake circuits to assist trainline application and release, and service braking can be used at will. WHen the train is put into emergency, the emergency contactor opens cutting all power and dynamic braking from traction motors, backfeeding the straight air pipe through spotting wire and the emergency porting reopens and admits main reservoir air into the cylinders, all almost simultaneously. It is air from the main reservoir that stops the train in emergency, and when the train is fully charged. |
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| (697617) | |
Re: Air Brakes/BIE Question |
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Posted by SelkirkTMO on Sat Oct 25 00:18:53 2008, in response to Air Brakes/BIE Question, posted by gbs on Fri Oct 24 23:56:25 2008. There probably isn't a more useful explanation than this ...
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| (697638) | |
Re: Air Brakes/BIE Question |
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Posted by Jeff H. on Sat Oct 25 01:24:38 2008, in response to Air Brakes/BIE Question, posted by gbs on Fri Oct 24 23:56:25 2008. Because there are two trainline air pipes. The Straight Airpipe is used in service braking, and increasing pressure corresponds to increasing brake rate. The Brake Pipe is the safety pipe. A loss of air in the brake pipe causes the brakes to apply, on each car, at full strength. What you hear is the release of air from the Brake Pipe. As BLE/NIMX explained, there is a lot more going on under the car than you might think. |
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| (697664) | |
Re: Air Brakes/BIE Question |
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Posted by Bill West on Sat Oct 25 03:24:29 2008, in response to Air Brakes/BIE Question, posted by gbs on Fri Oct 24 23:56:25 2008. I think we are overcomplicating the answer.Westinghouse’s basic 1872 idea for fail safe automatic brakes was that the air for the brake cylinders would be stored in a reservoir on each car and that the train brake pipe could then be worked with a reverse logic. -A “triple valve” on each car did the necessary reversal of logic in activating the cylinders from the reservoir. -BP pressure could then cause release and a lack of pressure would cause apply. -The triple valve also took care of recharging the car reservoir from the brake pipe whenever it was back up to pressure. The previous 1868 “straight air” system had the catch that train-break-in-two’s left the engineer with no brakes at all, the automatic system reversed that so that breaking the air line automatically caused a stop. The other posts then cover the evolution to electro pneumatic speed up of the control, the overlay of straight air for fast response and other refinements. Bill |
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| (697665) | |
Re: Air Brakes/BIE Question |
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Posted by SelkirkTMO on Sat Oct 25 03:27:37 2008, in response to Re: Air Brakes/BIE Question, posted by Bill West on Sat Oct 25 03:24:29 2008. THANKS, Unca Bill! You know how it is with us tekkies. :) |
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| (697693) | |
Re: Air Brakes/BIE Question |
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Posted by JournalSquare-K-Car on Sat Oct 25 10:09:12 2008, in response to Re: Air Brakes/BIE Question, posted by SelkirkTMO on Sat Oct 25 00:18:53 2008. Strange, that diagram is more complex than the propulsion/electric diagram. But the brake system seems to have three systems in one, and failsafes, unlike the electric one. And that diagram doesn't seem to get into dynamic braking details, since then it would require the resistors, cam and motors. |
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| (697753) | |
Re: Air Brakes/BIE Question |
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Posted by SelkirkTMO on Sat Oct 25 15:09:06 2008, in response to Re: Air Brakes/BIE Question, posted by JournalSquare-K-Car on Sat Oct 25 10:09:12 2008. That's just the plumbing and air part of it. The electricals are an overlay to all that. Yes, braking systems are incredibly complex, and for good reason. Goes back to one of my favorite sayings from schoolcar, "any idiot can make a train go ... takes some SKILL to make it stop." :) |
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| (697759) | |
Re: Air Brakes/BIE Question |
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Posted by BLE-NIMX on Sat Oct 25 15:51:10 2008, in response to Re: Air Brakes/BIE Question, posted by JournalSquare-K-Car on Sat Oct 25 10:09:12 2008. Anything you might know about the dynamic braking, just insert it into the dynamic actuator box knowing the lockout valve is to block brake cylinder air when dynamic brake is working, and flow air when it is not working, scheduled to drop out at low speeds or when brake pipe is in emergency |
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| (697771) | |
Re: Air Brakes/BIE Question |
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Posted by Fulton Frank on Sat Oct 25 16:54:43 2008, in response to Air Brakes/BIE Question, posted by gbs on Fri Oct 24 23:56:25 2008. This is my favorite explanation of the system..http://www.railroad.net/articles/railfanning/airbrakes/index.php It's not too techie and not too simplistic either. It really all revolves around the triple valve, doesn't it. It's the heart of the "negative logic" system Bill mentions above. |
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