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Post by Deleted on Mar 22, 2005 22:31:18 GMT
1. Where are the compressors that keep the air main pressurized?
2. Are folks like Mr. Crame responsible for fixing them when they go SPLAT?
3. What pressure is the air main kept at?
4. Is it true that the air main is used as a convenient earth terminal?
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Tom
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Post by Tom on Mar 22, 2005 23:12:53 GMT
1. Substations
2. Sadly yes we are.
3. 60PSI (4.something bar)
4. Yes, the air main is one of the earths used for signalling circuits.
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Post by Deleted on Mar 22, 2005 23:14:48 GMT
I take it then that they are not too reliable?  |
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Post by Deleted on Mar 22, 2005 23:54:47 GMT
3. 60PSI (4.something bar) . Virtually the same as a Trainline pipe. |
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Tom
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Post by Tom on Mar 23, 2005 0:16:47 GMT
I take it then that they are not too reliable? Not really; when it works it's very reliable. However when it goes wrong it can be a bit of a PITA. |
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Post by igelkotten on Mar 23, 2005 0:27:11 GMT
Virtually the same as a Trainline pipe. And how much is that in kPa, for us imperially challenged furriners? About 450 kPa or so? Not that high pressure, in other words. Interesting that LU uses so low a pressure for the trainline. Our old units also used Westinghouse brake valves (we being the only one in Sweden to use them to any extent), but we use a trainline pressure of about 95-100 PSI, if I have converted things correctly. Does anyone happen to know why that particular level of pressure was selected? /Igelkotten |
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Post by Dmitri on Mar 23, 2005 8:37:41 GMT
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Tom
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Post by Tom on Mar 23, 2005 8:49:57 GMT
60PSI = 413.68kPa In terms of reliability, the weaknesses are that if water condenses in them and then freezes you can have a few 'interesting' times, though it isn't as bad as trainstop and point motors freezing. The last failure I know of was when two isolating cocks were operated to make a section of air main dead, however nobody knew when operating the second cock that the first had also been operated!  |
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Post by Admin Team on Mar 23, 2005 9:26:31 GMT
Virtually the same as a Trainline pipe. Sounds like you've got a bit of a leak there then Jim! On a C Stock the Trainline normally sits at about +/- 75 psi with the Main Line at about +/- 95psi. Our were you meaning that the 'minimum prssure' required to allow the Control Governor needs about that? (To our non LU readers, I apologise for this slightly 'techie' stuff!) |
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Post by Deleted on Mar 23, 2005 15:37:57 GMT
yes its fun and very noisey when we have a blow on the air main last time i had a failure on the air main was at west kenisngton and apprently the phone lines at the NCC and broadway never stopped all night
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Post by Deleted on Mar 23, 2005 21:42:10 GMT
Sounds like you've got a bit of a leak there then Jim! On a C Stock the Trainline normally sits at about +/- 75 psi with the Main Line at about +/- 95psi. Thats what i thought! lol Going back to the air main, if a trainstop fails because of an obsruction under the head, you must not use your foot or hand to remove it, as iam lead to believe that 60psi pusshing a lump of metal down, can be quite harmful! ;D |
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Post by Deleted on Mar 23, 2005 21:48:55 GMT
Thats what i thought! lol Going back to the air main, if a trainstop fails because of an obsruction under the head, you must not use your foot or hand to remove it, as iam lead to believe that 60psi pusshing a lump of metal down, can be quite harmful! ;D Hopefully no one has injured themselves this way; not only would it probably be quite damaging, but they may never live it down! |
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Post by Deleted on Mar 23, 2005 21:57:42 GMT
Hopefully no one has injured themselves this way; not only would it probably be quite damaging, but they may never live it down! According to our trainer at the school, it would break for hand or foot! |
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Tom
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Post by Tom on Mar 24, 2005 12:50:35 GMT
I can confirm that any injury from air operated signalling equipment will cause serious damage to people.
While removing obstructions isn't really an issue (as long as you turn the air off or remove the valve stem), one that can hurt is getting hit in the ankle by a point escapement or WL slide.
It's not entirely untrue that when doing point failures on the Technical Officer's course the assessor spends as much time looking at how you move around the points and where you put your feet as he does assessing how well you handled the failure from a technical perspective.
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Post by Deleted on Mar 24, 2005 12:55:14 GMT
While removing obstructions Talking of which, the padles that are in the PODs in the train cabs, have a good use for getting rid of any obstructions! |
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Post by igelkotten on Mar 24, 2005 22:46:17 GMT
I can confirm that any injury from air operated signalling equipment will cause serious damage to people. While removing obstructions isn't really an issue (as long as you turn the air off or remove the valve stem), one that can hurt is getting hit in the ankle by a point escapement or WL slide. It's not entirely untrue that when doing point failures on the Technical Officer's course the assessor spends as much time looking at how you move around the points and where you put your feet as he does assessing how well you handled the failure from a technical perspective. Likewise, electrically operated points can give you some very nasty injuries if they decide to throw as you are clearing out some kind of obstacle from the point mechanism or the point blades. While the blades are supposed to stop moving if they hit an obstruction, the initial throw is powerful enough to crack a laptop computer, for example. (empirically proven.) |
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Tom
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Post by Tom on Mar 24, 2005 22:56:38 GMT
As I understand it, your point machines work on a 'if at first you don't succeed, try and try again' principle, so I can quite undertand them cracking a laptop.
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Post by igelkotten on Mar 24, 2005 23:05:25 GMT
As I understand it, your point machines work on a 'if at first you don't succeed, try and try again' principle, so I can quite undertand them cracking a laptop. Depends a bit on what kind of point it is, where it is located, and what the last "order" it recieved were, but yes, in some cases it is "three tries and reset". Ouch. |
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Post by Deleted on Mar 25, 2005 2:24:50 GMT
Sounds like you've got a bit of a leak there then Jim! On a C Stock the Trainline normally sits at about +/- 75 psi with the Main Line at about +/- 95psi. Our were you meaning that the 'minimum prssure' required to allow the Control Governor needs about that? I think I'm cracking up! It's not too many years since I worked on both "A" and "C" stock's, I've even still got the stock handbooks at home. I've got it in my head that the Trainline's 65lbs psi , and the Mainline's 80lbs psi. I accept that I'm probably wrong, I've got too settled into the simplicity and comfort of "D" stock in my old age, I probably couldn't do a Westinghouse to save my life now |
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Post by Admin Team on Mar 25, 2005 8:44:18 GMT
I think I'm cracking up! It's not too many years since I worked on both "A" and "C" stock's, I've even still got the stock handbooks at home. I've got it in my head that the Trainline's 65lbs psi , and the Mainline's 80lbs psi. I accept that I'm probably wrong, I've got too settled into the simplicity and comfort of "D" stock in my old age, I probably couldn't do a Westinghouse to save my life now Here's a little reminder for what they look like Jim photobucket.com/albums/v663/districtdave/Odds%20and%20Ends/?action=view¤t=C69Guages.jpgHave a word with the DMT next time you have a P&D - see if you can come down west for a refresher - I'm sure you'll find a friendly I/O or two who could take you out for a rounder or three!  |
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solidbond
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Post by solidbond on Mar 25, 2005 10:22:54 GMT
I think I'm cracking up! It's not too many years since I worked on both "A" and "C" stock's, I've even still got the stock handbooks at home. I've got it in my head that the Trainline's 65lbs psi , and the Mainline's 80lbs psi. I accept that I'm probably wrong, I've got too settled into the simplicity and comfort of "D" stock in my old age, I probably couldn't do a Westinghouse to save my life now To clarify, the Train Line was indeed 65psi, and Main Line nominally 85psi. About 10-12 years ago, after carrying out the annual brake testing on the South Ealing test track, it was decided that the Westinghouse on C stock could do with being improved. As a result, Train Line pressure was increased to 70psi, but Main Line remained at 85psi. The fact that a lot of C stock have 75psi of Train Line is more down to the feed valve being incorrectly set There will always be variations in the Main Line pressure, as you have to have a wide range on the governor settings to prevent the compressors working all the time. I believe the range is officially 80-90psi, but I could be wrong about that. The safety valves on the C stock have been upped from 105psi to 110psi in the last couple of years, but I am not sure if this corresponded with an increase in the pressure range settings. |
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Post by Deleted on Mar 25, 2005 11:34:57 GMT
And a reminder of what an A stock air guage looks like:  |
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Post by Deleted on Mar 25, 2005 16:37:24 GMT
To clarify, the Train Line was indeed 65psi, and Main Line nominally 85psi. About 10-12 years ago. Ah, thanks, SB, for that, I'm not completely nuts then I honestly don't remember the pressures changing though, unless that happened when i was on the Central working 92's |
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Post by Deleted on Mar 25, 2005 21:48:46 GMT
yeah we had a set of points from sweeden called ebiswitch i think thats how it was spelt the set was in signal house at acton on trial but there was or two problems like they only ran on a 3 phase motor and the 1st sleeper which housed all the equipment was made of metal so earths would of been a nightmare and if any of the equipment needed changing u would need the p way out everytime. but they were very good they could crush a piece of ballast not like our silly points which just fail so they got my thumbs up
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solidbond
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Post by solidbond on Mar 25, 2005 22:57:58 GMT
Ah, thanks, SB, for that, I'm not completely nuts then No comment ;D ;D ;D |
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Tom
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Post by Tom on Mar 25, 2005 23:13:29 GMT
yeah we had a set of points from sweeden called ebiswitch One of our Senior Techs went to look at them (in Malmö IIRC) and I've seen the set in Signal House myself, I don't think they're the standard Swedish point machine that I know and love though. |
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