Page 1 of 1
| Electric token block instruments 06/10/2019 at 13:55 #120758 | |
Muzer
718 posts |
I can find loads of websites explaining in great detail how electric token block works from the driver and guard's perspective and loads on different variations of instrument types, tokens, etc., but I can't find a page explaining simply the electrical principles behind the operation. I'm sure I've found such a page in the past but I can't find it now and it's really annoying me. So could someone explain how electrically the token locking works? Log in to reply |
| Electric token block instruments 06/10/2019 at 14:13 #120759 | |
Edgemaster
332 posts |
There's some circuit diagrams for various single line block systems here: http://dickthesignals.co.uk/onewebmedia/signalling%20a%20single%20line.pdf (You've got me searching for more online resources, now too) Also: http://dickthesignals.co.uk/onewebmedia/9%20operation%20of%20single%20lines.pdf Last edited: 06/10/2019 at 14:16 by Edgemaster Reason: None given Log in to reply The following user said thank you: Muzer |
| Electric token block instruments 06/10/2019 at 14:24 #120760 | |
|
Muzer
718 posts |
Cheers, I saw the second one but not the first! My friend and I are still having great difficulty working out the non-standard symbols in that first one though...
Log in to reply |
| Electric token block instruments 06/10/2019 at 14:32 #120762 | |
|
Edgemaster
332 posts |
I'm less familiar with the electrical side of signalling, it's an area in which I've intended to do some further study. By non-standard, do you mean deviating from the electrical symbol standards, or the more specialist railway signalling wiring diagram standards?
Log in to reply |
| Electric token block instruments 06/10/2019 at 15:11 #120764 | |
|
Muzer
718 posts |
The former - I didn't know there was a standard for railway wiring diagrams but I suppose that makes sense! Maybe that will help me interpret it...
Log in to reply |
| Electric token block instruments 06/10/2019 at 15:36 #120765 | |
|
Edgemaster
332 posts |
Some various relevant (former) standards in the RSSB catalogue: GK/RT0205-1 Symbols for Signalling Circuit Diagrams GK/RT0004-1 Symbols for Use on Signalling Plans and Sketches GK/GN0600-1 Signalling and Operational Telecommunications Design: Technical Guidance BR1654-2 Radio Electronic Token Block System Log in to reply The following user said thank you: Muzer |
| Electric token block instruments 06/10/2019 at 21:10 #120772 | |
|
clive
2781 posts |
The basic answer on how it works … There are two wires from the internal logic to the lock where the tokens are inserted and removed and from there along the telegraph wires to the other machine. Every time a token is inserted or removed the connections between the internal and external wires are reversed (so instead of internal wire A connecting to external wire A and B to B, it changes to have A connected to B and B to A). Tokens can be inserted at any time by rotating the lock one way, but to remove one - by rotating the lock the other way - an electric latch on the lock must be energised. This latch, in turn, is powered from the wires through a diode. So one signalman presses the button to release a token. This connects a battery to the wires with positive on line A and negative on line B. If both locks are in the same position (either A-A/B-B or A-B/B-A) then at the far end you'll get positive on line A and current will flow through the diode to lift the latch. The token can then be removed. But if the locks are in opposite positions then you'll get *negative* on line A, the diode will block the current, and the lock stays firmly locked. So you can only release a token when the locks are in the same positions and that changes them to opposite positions. Putting the token back (in either machine) restores them to the same positions again. Hope this makes the concepts clear. The rest is just details. Log in to reply The following users said thank you: Muzer, Steamer, TUT |
| Electric token block instruments 06/10/2019 at 21:45 #120773 | |
|
Muzer
718 posts |
Perfect, that's the sort of simple explanation that I knew I'd read somewhere in the past but couldn't find, much appreciated Clive! One thing, I imagine they would have used some naturally polarity sensitive lock rather than specifically a diode back in the day since I don't imagine they had decent diodes when these were first invented! Log in to reply |
| Electric token block instruments 07/10/2019 at 06:23 #120778 | |
d233
8 posts |
And if, the sent train on the token has broken and it needs to be towed, then how? (text via Google translator) Russian Railways Log in to reply |
| Electric token block instruments 07/10/2019 at 09:35 #120781 | |
|
jrr
95 posts |
No idea for token but with a staff the fireman had to take the staff to the signal box. The rescue loco then took the staff and fireman back to the failure. This got used several times when I signalled on a heritage railway.
Log in to reply |
| Electric token block instruments 07/10/2019 at 10:14 #120784 | |
headshot119
4869 posts |
d233 in post 120778 said:And if, the sent train on the token has broken and it needs to be towed, then how?In simple terms. In the scenario that the train has failed in the section between box A and box B the token remains with the failed train. The signaller at Box A will agree with the signaller at Box B what is to happen, and allow an assisting train onto the single line without a token. EDIT This is under the current regulations, on a line signalled with Electric Token Block regs. "Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer Last edited: 07/10/2019 at 10:17 by headshot119 Reason: Edit to clarify era context Log in to reply |
| Electric token block instruments 07/10/2019 at 12:33 #120788 | |
|
clive
2781 posts |
Muzer in post 120773 said:Perfect, that's the sort of simple explanation that I knew I'd read somewhere in the past but couldn't find, much appreciated Clive!You're welcome. Muzer in post 120773 said: The actual term is "polar relay". I always think of it as a relay with a diode in series but it almost certainly isn't. Sorry for any confusion. Log in to reply |
| Electric token block instruments 07/10/2019 at 21:31 #120819 | |
|
Muzer
718 posts |
headshot119 in post 120784 said:d233 in post 120778 said:Presumably today with the network covered by radio you can have a much more positive assurance that the train is definitely broken and the driver isn't going to start moving again having fixed it! Back in the day I can certainly understand the taking the token to the box - without it the remaining traincrew know they're not to move!And if, the sent train on the token has broken and it needs to be towed, then how?In simple terms. Log in to reply |
| Electric token block instruments 07/10/2019 at 22:42 #120822 | |
pedroathome
915 posts |
I was reading not too long ago in an old sectional appendix for the Western end of the Western (1973 copy I think, given it still made reference of the former through platforms at Plymouth), on the Gunnislake Branch, if a train failed between Bere Alston and Gunnislake (i.e. after the train has reversed), that the token was to be walked to Bere Alston so the ground frame could be worked. There was no mention of returning it to St Budeaux (Whichever was the LSWR station)
Log in to reply |