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| Points Failure 05/01/2010 at 17:38 #480 | |
AndyG
1834 posts |
Kieran, have a look at the WIKI - here No doubt one of the "pros" will explain better. I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |
| Points Failure 05/01/2010 at 17:38 #5538 | |
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AndyG
1834 posts |
Kieran, have a look at the WIKI - here No doubt one of the "pros" will explain better. I can only help one person a day. Today's not your day. Tomorrow doesn't look too good either. Log in to reply |
| Points Failure 05/01/2010 at 18:20 #5539 | |
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Noisynoel
989 posts |
Keiran, There are several different states of failure.. Failed normal - This means that the signaller has detection in the normal position, but cannot get detection in the reverse position, and can therefore signal over the points in the normal position normally. Failed reverse - This means that the signaller has detection in the reverse position, but cannot get detection in the normal position, and can therefore signal over the points in the reverse position normally. Failed out of correspondance (OOC) - This basically means that the points are flashing out of correspondance preventing the signaller from getting detection in either position. In this case the signall has to wait for either a MOM (Mobile Ops Manager) or S&T to attend. They would then either, rectify the fault or secure the points in which ever position the signaller requires. If secure by clip & scotch it may or may not be possible to get detcetion. If detection gained then the above applies for failed normal/reverse. If no detection obtained then the signaller will have to talk trains past the protecting signal. Once the points have been secured then the signaller should collar (put a reminder on) the points in the position they have been secured to prevent him trying to move them.. Noisynoel Log in to reply |
| Points Failure 05/01/2010 at 18:37 #5540 | |
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pilotman
189 posts |
Hi Kieran. Just to add a little to NoisyNoel's excellent reply. Out of correpondence implies that both ends of a crossover are detected, but one is normal the other reverse - not really a useable situation. This can happen if one point motor fails. Motor points can be hand wound, and detection should then be achieved, assuming no other problems, thus signals can be operated. There is usually a power cut off arrangement so that as soon as the points motor case is opened (or the winding handle is inserted) the primary power is disabled. I believe detection fails at typically 3mm so quite tight. If points are clipped and accidentally switched there is a cut out after typically 11 seconds to prevent damage to the motor. I would just add that if detection is obtained as above there is no requirement to clip and plug. Hope this is of interest. Log in to reply |
| Points Failure 05/01/2010 at 22:46 #5546 | |
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clive
2738 posts |
Pilotman: a crossover with one end pointing in each direction would cause "out of correspondence", but it's pretty unlikely and it's by no means the only cause. Each set of points have N and R detectors which drive a relay if the points are correctly positioned and locked. For the interlocking to accept that a set of points are normal, all the N detector relays must be up, none of the R detector relays must be up, and the interlocking's last action on the points must have been to attempt to move them to normal; the converse is true for reverse. If neither are the case, the "out of correspondence" light or indication comes on, so it is on both while the points are moving or if any end (and some points have up to 6 ends) is not detected in the correct position, or if they're not in the expected position. Log in to reply |
| Points Failure 06/01/2010 at 09:43 #5549 | |
GeoffM
6282 posts |
Noel's definition of "failed normal" and "failed reverse" had me wondering - it matches the Wiki page but isn't what I expected. So I canvassed some signallers and signal engineers. Here are the three interpretations they came up with: 1. Failed normal means detection has failed in the normal position [does not imply motor failure, only detection failure] 2. Failed normal means they are in the normal position and cannot be moved to the reverse position [does not imply detection, only motor failure] 3. Failed normal means detection has failed in the reverse position. But what they all agreed on was that the statement is ambiguous and instead "failed normal/reverse detection" or "failure to move normal/reverse" should be used instead. I shall henceforth retrain myself to be more specific! To confuse the matter slightly, some installations allow trailing sets of points flanking the route (not in the route) to be OOC which allows trains to be given clear signals through the unaffected end of the crossover. In this case each end is detected, and usually indicated to the signaller, seperately. SimSig Boss Log in to reply |
| Points Failure 06/01/2010 at 18:54 #5555 | |
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pilotman
189 posts |
Clive I accept that this is unlikely, but we have had this type of failure with Westinghouse HW points on the Bluebell rly. I don't understand when you say "this is not the only cause" as you haven't actually defined a cause. Ray Log in to reply |
| Points Failure 06/01/2010 at 20:07 #5556 | |
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eddy
45 posts |
Gentlemen. Two definitions exist for point correspondence. Correspondence.This ensures that the signal box controlling device (switch or lever) controls (relay) and indications (panel) correspond with the lie of the points for both normal and reverse positions. Out of Correspondence. This ensures that detection cannot be obtained if one or more ends are not in the correct position. regards eddy Log in to reply |
| Points Failure 07/01/2010 at 23:06 #5590 | |
DriverCurran
683 posts |
Have seen the one end only type failure a couple of years ago, Waiting to take over a set of empties at St Leonards depot, it quickly became clear that the depot end of the crossover was staying normal while the mainline end had gone to the correct reverse position Paul You have to get a red before you can get any other colour Log in to reply |
| Points Failure 08/01/2010 at 09:01 #5599 | |
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clive
2738 posts |
Sorry, I'm not saying that mismatch between the two ends of a crossover doesn't happen. I was just objecting to the implication that this was the only meaning of "out of correspondence". What I'm saying is that, at least in relay interlockings, the "OOC" light comes on unless *every* end is proven to be in the position that the interlocking is expecting. Thus the light flashes while the points are moving, for example. In particular, it will come on if every end is locked normal but the interlocking thinks the points should be reversed. As to what causes a fault, there's a whole range of possibilities. A piece of ballast blocking the blades. A motor failure. A broken wire in the detector. Etc. Log in to reply |
| Points Failure 08/01/2010 at 13:53 #5608 | |
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kbarber
1712 posts |
clive said:
Or perhaps the most common - that the detection has drifted out of adjustment (thermal, vibration, etc - it's pretty hostile in a point machine). Log in to reply |