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| Traditional signal levers 15/12/2015 at 08:52 #78734 | |
canis
15 posts |
You know, the big'uns on the floor in the old fashioned boxes, I have a question for anyone familiar with using them. I'm trying to write a small signal-box simulator for a telnet MUD (they were popular before minecraft and facebook and for some reason I still use them) and I've been using this site as a guide. Now right at the bottom of the page it talks about levers being "normal" or "reversed". My question is this: Is it normal when pulled? Or when pushed? And what is normal anyway? For example, is it 'normal' for the up line to have it's signals 'off', or 'on' at danger? And what happens with points? Which way is normal then? Can someone with knowledge of traditional signalboxes fill me in? Thanks. Log in to reply |
| Traditional signal levers 15/12/2015 at 09:23 #78736 | |
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JamesN
1607 posts |
U" said:You know, the big'uns on the floor in the old fashioned boxes, I have a question for anyone familiar with using them.In its simplest guise, Normal is away from the signaller then you pull the lever Reverse towards you. Log in to reply The following user said thank you: canis |
| Traditional signal levers 15/12/2015 at 10:36 #78737 | |
KymriskaDraken
963 posts |
As always with Railway Signalling you need to bear in mind that things have evolved over time and different Railway Companies did things in a slightly different way. The usual method, as James said, has the levers Normal when back in the frame and Reverse when pulled. So signals at Danger/Caution will have their levers Normal, and clear signals will have the levers reversed. With Absolute Block signalling it is usual to keep the signals at Danger/Caution until there is a train on the way, although I don't think that there is a Rule that prevents the Signalman "asking the road" and pulling off for a train well in advance. Points are Normal for straight running, and Reverse for the turnout. However, with some points, particularly in a complex junction it isn't immediately obvious which is Normal or Reverse. However all points are marked on the Signalbox diagram and are usually shown in the Normal position. In addition, point ends (A and B) are labelled with the A end nearest the Signal Box. As with Signals point levers are Normal in the frame, and pulled over Reverse. Facing Point Locks are generally an exception - the lever will be Reverse in the frame to lock the points, and Normal to release the points. Kev Log in to reply The following user said thank you: canis |
| Traditional signal levers 15/12/2015 at 10:45 #78738 | |
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kbarber
1742 posts |
" said:U" said:You know, the big'uns on the floor in the old fashioned boxes, I have a question for anyone familiar with using them.In its simplest guise, Normal is away from the signaller then you pull the lever Reverse towards you. As James says, 'Normal' is usually when levers are pushed back in the frame[sup]1[/sup]. When levers are Normal, signals will usually be showing their most restrictive aspect[sup]2[/sup]. When levers are Normal, points will tend to be set for the straight route. It's here that you'll find the most variety though. Sometimes, regardless of how it looks on the signalbox diagram, there's no obvious straight route out on the ground. In that case the Normal lie of points is whatever the Signal Engineer decided it would be (or whatever the operators demanded). There are times when the main line (as it is on the ground) shows on the box diagram as curving away from a branch that goes straight ahead (Balham http://www.wbsframe.mste.co.uk/public/Balham.html is a case in point - there's quite a decent photo of the diagram towards the bottom of the page). Some railways had a fashion to have the facing points at a junction lie Normal for the left hand route regardless of its importance, thus providing trapping protection with junction points normal (an intriguing example at Arnside http://www.signalbox.org/diagrams.php?id=28 where the trapped move ran straight on to a single line - see No.16/17/18 points). Occasionally the normal lie would be in an unexpected direction, often to provide a catch point, as here at Beattock North http://www.signalbox.org/diagrams.php?id=258 where 22 normal acts as a catch point in case of vehicles running back down Beattock Bank. (And, yes, that would mean 16 normal got run through; under those circumstances I suspect that would have been the least of your problems!) The one thing you can be sure of - the box diagram will show the way the points are set with their lever Normal. Facing point locks could either be Normal 'In' (i.e. you pull to unlock) or Normal 'Out' (pull to lock). I think the latter were more common but I'm open to correction. Sometimes you might find both in the same box, apparently set up for the greater convenience of the signalman. And at Bewdley South there's one that's both at once - No. 12 FPL http://www.svrsig.org.uk/svr/Frame2.htm locks 13 points when reversed and 10 points when normal! Bolt locks, where a lever in one box locked something (most often points but could be a bridge bolt or somesuch) in another would, I suspect, most often be in the locked position when normal. But I'm pretty certain there will be exceptions. Canis: there's a significant number of signalling diagrams on the site you're using, they will give you a very good idea of typical layouts. (If there's an article referenced from a diagram it will usually point to a discussion on the forum that's attached to that site (The Blower), and it may mean that location is atypical for some reason - always worth checking out.) The Blower is a superb resource, in any case, for enthusiasts of traditional signalling. [1] Some companies made use of 'Push-Pull' levers, where the normal position would actually be the mid-position. In those cases you won't find a Reverse position referred to as such, there will always be 'Push' or 'Pull'. The London & South Western was a prolific user of these levers (I've an idea they were invented by one of their engineers and it avoided the need to build new boxes as track layouts expanded). See http://www.signalbox.org/diagrams.php?id=392 for an example. Some of the early power frames also had push-pull levers. [2] There were some locations where shunt signals would be 'normally off'; it was quite common to find a pair of opposing shunts on one lever, so that when it was normal in the frame the shunter could just get on with it. We had a couple like that at Marylebone (the 1967 box, replaced by the IECC of the sim). Last edited: 15/12/2015 at 12:19 by kbarber Log in to reply The following user said thank you: canis |
| Traditional signal levers 15/12/2015 at 11:40 #78739 | |
headshot119
4869 posts |
" said:I would agree that the latter is / were more common, though I know a few places where the former was the norm. As for shunt signals being normally off I can think of two places not far from me at the moment where this is the case. Dee Marsh to allow trains to shunt between Birkenhead Sidings and the Steel Works Reception Sidings. Shotwick ground frame to allow trains to shunt between the headshunt and the paper mill. "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Log in to reply The following user said thank you: canis |
| Traditional signal levers 15/12/2015 at 20:41 #78748 | |
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Stephen Fulcher
2078 posts |
FPLs standing in are fairly common on ground frames.
Log in to reply The following user said thank you: canis |
| Traditional signal levers 16/12/2015 at 09:43 #78758 | |
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Danny252
1461 posts |
" said:Facing point locks could either be Normal 'In' (i.e. you pull to unlock) or Normal 'Out' (pull to lock). I think the latter were more common but I'm open to correction.At least in my experience of 20th century signal boxes, FPLs Normal 'Out' was by far the more common in British (or at least GWR/WR) practice. No. 12 in Bewdley South is regarded as quite a curiosity! I think US practice tended to prefer FPLs Normal 'In', but that's a fairly sweeping statement based off only a few examples I've seen. Stephen's comment about ground frames is quite right; I suspect the logic there was that all levers should be normal when a train left the ground frame, making it obvious to the train crew if they'd forgotten a lever! Expanding headshot119's list of opposing shunts, No. 16 at Bridgnorth to/from the loco yard headshunt is another example. The loco department can shunt away merrily as the signalman eats his lunch... Log in to reply The following user said thank you: canis |
| Traditional signal levers 16/12/2015 at 12:39 #78760 | |
Izzy
44 posts |
FPL's were more commonly designed to stand out of the frame (reverse lever position) for a very good reason - When you unlocked the points by putting the lever normal, it allows you a less hindered pull on the point lever (normally right next to the FPL) - point levers can be pretty heavy, and having the FPL standing out of the frame can seriously impede pulling (or even worse, pushing) a heavy lever. In cases where space was very restricted in the signal box, the FPL's may have been designed to stand in the normal lever position, but was not that common. But, there are always exceptions - and some companies preferred a tidier looking frame, with all the levers in the frame. In the frame, in this case refers to the normal position - a bit of slang creeping in there - in and out of the frame, normal and reverse respectively. Now to confuse the issue - certainly on the southern, if you read the notes on the signal box diagram (in a box with FPL's) - there will be a statement "FPL's stand normally in (or out)" . In a box where the FPL's stand normally out, the normal position of that lever is actually reverse - this is a terminology issue. In operational terms, the normal position of a lever is the position it would normally be in (with signals at danger, points normal, level crossing gates open to road traffic, FPL's locked) - so LX gate locks also normally stand in the reverse position in most cases as well. From a signalling engineering point of view, each position (and intermediate positions as well) of a lever has a specific name, Normal, A, B, Centre, D, E, Reverse (the capitals are how they are labelled on drawings - so you can find for example, a lever contact band labelled AE - this is made when the lever is NOT normal or reverse, or a band called NA which is only made when the lever is normal or just out of the frame. This is for full size lever frames - miniature power frames are slightly different. My point here is that to a signalling engineer, normal and reverse are distinct positions with relation to the position of the frame - whereas in an operational sense normal and reverse can be referred to the other way round depending on how the lever normally stands in the frame. Normal and reverse positions of points can be misleading. Generally, logic prevails and the normal position is the straightest route - but there are situations where this is not the case, normally when junction protection gets involved. A simple example of back to front normal and reverse would be a set of trap points at the end of a loop - normal would be the straight route - into the sand trap, and the reverse position would be the only position that you would expect trains to pass over this set of points. Normal and reverse in the naming of point positions can be pretty arbitrary at times - and it doesn't really matter, it is only a name for which way the points are lying on the ground. If one needs to know which is which for a particular set of points, you can refer to the diagrams (as well as a couple of other ways of telling, but i don't want to go into essay mode, hehe). The designer will try to keep it logical and in simple cases will do so, but as with everything in the world of signalling there are exceptions to most rules. Fianally, ground frames. As Stephen rightly pointed out, these normally are designed with the FPL standing IN the frame. The reason for this is that from a distance a casual glance will tell you if you have normalised everything before leaving. Everything in the same position looks correct - bear in mind the people who use ground frames are rarely signallers, but are shunters, guards or drivers who don't necessarily have detailed working knowledge of the signalling equipment, and certainly don't spend a couple of months training on each and every ground frame (unlike signallers, who can spend a couple of months training on the specific equipment in their signal box) - and the order of the day is to keep it logical - All levers in the frame, is an obvious way to tell at a glance if everything has been left as it should be. It should also be noted that heavy point levers are extremely rare on a ground frame, as the lever is normally right next to the set of points - whereas a mechanical set of points can be upto 300 yards away from a signal box - and all that rodding and cranks and mechanical linkages can make a lever very heavy to pull, hence my first point about being hindered by the FPL lever if it stands out of the frame. Basically, the further away the points, the heavier they are to pull - particularly if the rodding route goes round a curve. (Billingshurst and Hastings are two boxes that spring to mind that had an evilly difficult set of mechanical points in them because the rod run wasn't straight). I hope this all makes sense. Last edited: 16/12/2015 at 13:00 by Izzy Log in to reply The following user said thank you: canis |
| Traditional signal levers 16/12/2015 at 14:47 #78761 | |
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John 23
176 posts |
At Staverton Crossing GF (previously Staverton SB) on the S Devon Railway, the gate lock lever stands out (reversed) when the gates are unlocked, and usually across the railway. The lever is normal when the gates are locked across the roadway to permit the passage of trains. It is suggested to me that this arrangement predates the Road Traffic Act 1934 before which it was normal for the gates to be locked across the road (low traffic levels). Since then, it is normal for level crossing gates (where there are still gates!) to be across the railway, so the lever usually sits reversed, which paradoxically is normal! Log in to reply The following user said thank you: canis |
| Traditional signal levers 16/12/2015 at 16:14 #78765 | |
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KymriskaDraken
963 posts |
" said:The designer will try to keep it logical and in simple cases will do so, but as with everything in the world of signalling there are exceptions to most rules.Sometimes the designers had rather a perverse streak. At Little Mill Jn (on the Newport-Hereford line, fringing with Newport "Daffodill Jn" Panel and Abergavenny) we had a lever frame in the box, alongside the panel, which controlled the points and signals for the branch line to Glascoed ROF. It was basically a Ground Frame positioned in the box. There were some very awkward leads there. If we wanted to get a train from the Up line onto the Branch we had to pull two FPL levers reverse, then pull the crossover point lever that was between the two FPLs (all three levers being in consecutive positions in the frame), replace the FPLs, pull another point, pull another FPL, and finally the lever for the shunt signal controlling entrance to the Branch. Even when as a slim 19 year-old I was a bit too wide to comfortably get that crossover lever over in one pull, even though the points were practically outside the signalbox door! The other catch with that frame was that the points were in the overlaps of the Up Starter and the Down Home so I couldn't move anything if I had accepted a Down train (which was On Line from Pontrilas - 20 miles away) or until the overlap had timed out on the Up line. Of course, Sod's Law stated that no sooner had the Up overlap timed out than Abergavenny would be offering something on the Down. It was only one daily train that served the branch but it always seemed to appear at the wrong time! Kev Last edited: 16/12/2015 at 16:17 by KymriskaDraken Reason: Grammar (yes, I know I am a pedant) Log in to reply The following user said thank you: canis |
| Traditional signal levers 17/12/2015 at 05:34 #78812 | |
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canis
15 posts |
Thanks everyone. I was sorta expecting just glib answers and being made to look foolish, but as always with the SimSig community, you all did me proud! Thorough explanations, with just the right amount of wit make for interesting reading. In my case, with this being a telnet MUD, the difficulty throwing the levers can be ignored, save for the odd message like "You heave the lever forwards", etc. Problems such as nearby levers being in the way of the physical effort involved I think I shall leave out of the simulation. As for my questions about "What is normal?" - haha, it's as clear as MUD (pun intended), but I take the point about common sense, and as the designer of my ficticious signal box I shall adopt the same approach. I suppose it doesn't really matter as long as the player knows which way they are. What interested me in the project was levers locking other levers, which from a programming perspective will be an interesting logic to simulate. Not particularly difficult to code, but I suppose a personal fascination. If I were an artist, I'd draw a signalbox. I'm not, I code, It's what I do and it's my way of exploring the subject. :-) (although I did consider volunteering for the East Lancashire line, just so I could get in the box, but that's another story...) So I'm gonna start with a simple main line with a simple branch and see where it all leads. Thanks for all the information, folks. You guys rock! Man, I love this community! Much regards, ~Lee (aka Canis) Log in to reply |
| Traditional signal levers 17/12/2015 at 09:13 #78816 | |
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kbarber
1742 posts |
Presumably you're aware, Lee, that levers lock each other with 'first and last motion' - that is, the first slight movement of any lever locks all conflicting levers (within about 10 - 12mm of lever movement), but no levers are released until the very end of the lever travel (again the last 10 - 12mm). Some designs of frame have catch handle locking, which achieves the same thing - you can't even pull the catch up to start moving the lever until all conflicting lever catches are locked. Locking design and lever layout is an art in itself. A simple main line/branch junction shouldn't - at least in theory - make too many problems. But getting it to look right can be a real challenge. (Remember the history of a box may have an impact as well. If you look for the signal diagrams for St Albans South on the Signalbox site you've been using, you'll see a whole series starting in the very early days of the box. What started as a very logical layout according to the standards and preferences of the owning company was progressively modified according to the needs of an amended layout, the new standards and preferences and the availability of spare levers. So the layout of the up direction signals is a real dogs breakfast because that was the only way they could do it without wholesale relocking of the frame, while the down direction signals are as logical as can be.) If you wanted to run a proposed diagram and locking table past us, I'm sure there's plenty here who have real-life signalling and signal engineering experience who'd be happy to look it over. Log in to reply The following user said thank you: indian_railways_fan |
| Traditional signal levers 17/12/2015 at 10:01 #78818 | |
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JamesN
1607 posts |
A little bit of reading for those who don't understand what MUD is. As such, diagrams and the ilk are an unlikely luxury! Walks into the operating room All the signallers are sat drinking tea with their feet up, letting ARS do the work... Last edited: 17/12/2015 at 10:04 by JamesN Reason: Hit submit instead of preview Log in to reply |
| Traditional signal levers 17/12/2015 at 16:12 #78836 | |
DriverCurran
688 posts |
And just to muddy the waters even more, there are also some levers that stand normal when mid frame, where going to either the back of the quadrant or front of the quadrant result in the lever being technically reversed. :whistle: and I shall call that taxi now  Paul You have to get a red before you can get any other colour Log in to reply |
| Traditional signal levers 17/12/2015 at 20:41 #78869 | |
BarryM
2158 posts |
Were they not used in conjunction with level crossings? Barry Barry, Sydney, New South Wales, Australia Log in to reply |
| Traditional signal levers 17/12/2015 at 20:52 #78870 | |
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DriverCurran
688 posts |
Mostly used as an economy measure for shunt signals on crossovers, pushing would clear one of the shunts and pulling would clear the other Paul You have to get a red before you can get any other colour Log in to reply The following user said thank you: BarryM |
| Traditional signal levers 18/12/2015 at 11:34 #78886 | |
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kbarber
1742 posts |
" said:And just to muddy the waters even more, there are also some levers that stand normal when mid frame, where going to either the back of the quadrant or front of the quadrant result in the lever being technically reversed. :whistle: and I shall call that taxi now Yes, those are the push-pull ones I mentioned. Perhaps best not to mention Russell levers http://www.signalbox.org/diagrams.php?id=214 at all! Log in to reply |
| Traditional signal levers 18/12/2015 at 12:14 #78887 | |
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headshot119
4869 posts |
" said:" said:Oh go on Keith whats a Russel lever when it's at home?And just to muddy the waters even more, there are also some levers that stand normal when mid frame, where going to either the back of the quadrant or front of the quadrant result in the lever being technically reversed. :whistle: and I shall call that taxi now "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Log in to reply |
| Traditional signal levers 19/12/2015 at 09:39 #78948 | |
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kbarber
1742 posts |
" said:" said:" said:Oh go on Keith whats a Russel lever when it's at home?And just to muddy the waters even more, there are also some levers that stand normal when mid frame, where going to either the back of the quadrant or front of the quadrant result in the lever being technically reversed. :whistle: and I shall call that taxi now OK then. Very definitely a LSWR speciality (and I'm pretty certain there's none left in service). A way of getting extra levers into a cramped box (you didn't even need to extend the frame). Basically, three levers (yes, three) were installed in one single lever slot! If you look at the Tisbury diagram I linked to, crossover 5 (for example) and its shunt signals had Russell levers. The shunt signal levers were right at the back of the frame and emerged together from the slot; they were then cranked - 5A to the left and 5B to the right, so that they occupied the space between 4 and 5 (with just about room to get hold of and pull them). 5 came up through the slot in front of them and obviously blocked them when in the normal position. Pulling 5 over allows you to pull 5A or 5B (or perhaps even both... I suspect opposing locking was omitted, simply because there was no room to attach a tappet to those levers let alone to have a locking dog between them). As the LSW used Stevens frames as standard, the untidy effect of some levers having shorter strokes would not seem odd. Of course the crossover levers would stand slightly out of the frame even when fully normal, but again I guess the signalmen would get used to that. It made for a very cramped looking interior. If anyone has access to Adrian Vaughan's book 'Signalman's Reflections' (published by Silver Link, 1990), there's a couple of photos of Tisbury on pages 122 & 123. Log in to reply |
| Traditional signal levers 21/12/2015 at 10:42 #79038 | |
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Izzy
44 posts |
Driver Curran - Push Pull levers were a great way of saving on interlocking, as a lever couldn't be pulled and pushed at the same time - an arrangement often used on crossovers, as you say. When a lever is pushed, as in my other post, it is not reversed (except in the operational sense) but it 's position is normal - so a lever normal is actually giving a proceed aspect. If you read my last post again, the bit about lever positions and how they are named - then N is pushed, R is pulled, and C (centre) is in the middle (or normal position for that lever, confusingly). Don't you just love "standard" terminology!!!! Russel levers - ah yes - absolute (profanity deleted, hehe) to arrange mechanical locking for. I too doubt there have been any of these in use for many years. I don't know if any survived into preservation. There was also an arrangement for working 2 signals from one lever depending on point position - the last one i remember was at Eridge on the Uckfield line. A mechanical selector was provided on the Up Platform starter at Eridge (yes, there were two up platforms). Depending on the position of the points at the end of the platform the starter lever would clear either the loop or main signal - These were also referred to as A and B (i can't remember the signal number, although 10 sounds familiar) so assuming it was signal 10, the signals would have been numbered 10A and 10B. This arrangement was not that common, as all the mechanical interlocking for the two routes had to be identical to work from a single lever (except for the 1 set of points that was catered for by the mechanical selector). If i remember correctly, the lever was labelled Up Platform Starters, as opposed to just starter. Last edited: 21/12/2015 at 10:50 by Izzy Log in to reply |
| Traditional signal levers 21/12/2015 at 14:35 #79041 | |
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Jersey_Mike
250 posts |
" said:Driver Curran - Push Pull levers were a great way of saving on interlocking, as a lever couldn't be pulled and pushed at the same time - an arrangement often used on crossovers, as you say. When a lever is pushed, as in my other post, it is not reversed (except in the operational sense) but it 's position is normal - so a lever normal is actually giving a proceed aspect. If you read my last post again, the bit about lever positions and how they are named - then N is pushed, R is pulled, and C (centre) is in the middle (or normal position for that lever, confusingly). Don't you just love "standard" terminology!!!!Union Switch and Signal style interlocking machines were based around signal levers having 3 positions since as you pointed out, most signals could be paired in mutually exclusive sets. Signals were designated R or L for the Right or Left motion of the lever. This carried over into the Unit Lever panel era and even on some new signal installations. Also both US&S and GRS would occasionally connect multiple signals to the same lever with electric logic determining which was ultimately illuminated. These signals were given a letter designation in addition to L or R, like 6RA or 10LB. Log in to reply |
| Traditional signal levers 21/12/2015 at 21:53 #79067 | |
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clive
2789 posts |
" said:Somewhere - but out of reach until my leg works again - I have a book containing drawings of a whole range of mechanisms for tricks like that so as to reduce the number of levers in the frame. Log in to reply |
| Traditional signal levers 21/12/2015 at 22:14 #79068 | |
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clive
2789 posts |
" said:The basic form of tappet locking is fairly simple. There are two kinds of locking, which I think of as 2-notch and 3-notch. A 2-notch lock provides the logic "lever A must be in position X OR lever B must be in position Y", where each of X and Y can be normal or reverse (though it would be very rare for both to be reverse). If X and Y are both "normal", then only one of A or B can be pulled at a time (used to prevent conflicting actions). If X is "normal" and Y is "reverse", then lever B releases lever A (e.g. a home signal releasing a distant). A 3-notch lock provides the logic "lever A can only change state when lever B is in position X". It's used for things like a facing point lock - the points must only be moved when unlocked - or a ground signal that reads over both directions of a set of points but must be at danger to move the points. There are lots of more complicated things. If you want a three-way or more OR then you need things like a swinging tappet, while to get sequential locking you need other mechanisms. But you can do a lot with just those two bits of logic. Log in to reply |
| Traditional signal levers 21/12/2015 at 22:28 #79069 | |
Steamer
3984 posts |
Quick question regarding Facing Point Locks: On points with FPLs fitted, which are also used in the trailing direction, is it necessary for the FPL to be engaged for trailing movements? "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |
| Traditional signal levers 21/12/2015 at 22:29 #79070 | |
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headshot119
4869 posts |
It depends on how the interlocking was set up. I've seen it three ways: FPL has to be locked FPL can be either way FPL has to be unlocked. "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Log in to reply |