signal sequences

[jamesm]

On London Transport lines, at what stage after a train has passed a repeater signal at green does the aspect change to yellow?

James

[Deleted]

I believe the repeater turns yellow as soon as the train has passed, even if the train has not yet passed the signal it is repeating.

[Deleted]

That is correct as far as my understanding goes - each repeater , including fog repeaters each have their own block joint.

[mrfs42]

78revolutions said:

That is correct as far as my understanding goes - each repeater , including fog repeaters each have their own block joint.

I thought Fog Repeaters and repeaters were parallelled up. [1]

Might be wrong though - am thinking of a sequence with at least 2 auto sticks with FRs underneath both.

[1] there may be a back contact off the berth track circuit [2] of the auto that acts as a 'global' replace for that particular signalpost

[2] or am I thinking of the difference between outside fed and inside fed TQs?

Certainly a block joint for every individual aspect [3] would be rather cable-heavy.

[3] I'm thinking of green over green over green. (non-supressed)

[Deleted]

I'm not so sure about this - I think I've seen standalone repeaters stay green until the linked stop signal turns red; repeaters that drop to caution after passing them are more of an NR thing, aren't they?

Subsidiary repeaters, though, are a different story - mrfs42 can probably post lots of circuit descriptions on how a subsidiary repeater is extinguished as part of the stop signal returning to red.

[Harsig]

theonekea said:

I'm not so sure about this - I think I've seen standalone repeaters stay green until the linked stop signal turns red; repeaters that drop to caution after passing them are more of an NR thing, aren't they?

I would have said the exact opposite, the only exceptions as far as I am aware being platform repeaters. These of course remain green while the station starter is green for the information of staff other than the driver i.e. platform staff and guards (when we had them)

[Deleted]

as soon as the train goes past the blockjoint on the next track the repeater will go back to amber this drops the PGR (P= Repeating G = Signal R= Relay) and the amber is fed from a back / down contact and the green is fed from a front / up contact

platform repeaters just copy the station starter as it is fed from the same relay (GR G= Signal R= Relay)

[Deleted]

Ah - now it makes sense; I was probably thinking of a platform repeater, then.

[Tom]

mrfs42 said:

78revolutions said:

That is correct as far as my understanding goes - each repeater , including fog repeaters each have their own block joint.

I thought Fog Repeaters and repeaters were parallelled up. [1]

Might be wrong though - am thinking of a sequence with at least 2 auto sticks with FRs underneath both.

[1] there may be a back contact off the berth track circuit [2] of the auto that acts as a 'global' replace for that particular signalpost

[2] or am I thinking of the difference between outside fed and inside fed TQs?

I think you might be thinking about the Red Light Circuit, which is often used for things like repeater control and lighting.

[mrfs42]

tom said:

I think you might be thinking about the Red Light Circuit, which is often used for things like repeater control and lighting.

I think I was too; looking at what I actually wrote. A description of one of the circuits I was thinking of (at that time) for TOK:

2GVCR (R1) to arm of 2GR⁸: back contact of 2GR⁸ to 2V "ON" (1.1, 1; 2.2, 2 - paralleled up) then

2V "ON" 5 , 5.5: 5.5 to arm of 2GR⁷ 5 to back contact of 2GR⁸ - BX100 feed.

2GVCR (R2) to N/NX100 terminal to 2RE to arm 2GR⁷

Which isn't quite what we're discussing here, though. I think I deserve an award for impenetrability for this posting! ;D

[Tom]

It sounds very like a combined RE/GVCR circuit, but not quite how I would expect it.

Try this:
BX100 to 2GR^7B. 2GR ^7B to 2V 'On' 5, looped to 2 and 1.
2V 'On' 5.5 to 2GR^7A to 2RE thence to NX100.

2V 'On' 2.2 looped to 1.1, 1.1 to 2GR ^8B, 2GR^8A to 2GVCR ^R1, 2GVCR ^R2 to NX100.

[Deleted]

;D

[Deleted]

I'm glad I'm not the only one who is now totally confused!

[Tom]

It makes more sense on a drawing (but only just!).

[mrfs42]

tom said:

It sounds very like a combined RE/GVCR circuit, but not quite how I would expect it.

It was. RE/GVCR circuitry (if you can believe what I type) shows the ingenuity of Dell and the guaranteed [1] RE.

tom said:

Try this:
BX100 to 2GR^7B. 2GR ^7B to 2V 'On' 5, looped to 2 and 1.
2V 'On' 5.5 to 2GR^7A to 2RE thence to NX100.

2V 'On' 2.2 looped to 1.1, 1.1 to 2GR ^8B, 2GR^8A to 2GVCR ^R1, 2GVCR ^R2 to NX100.

Same circuit, different way of expressing it - I think. You've swapped arms

I was quoting from memories of the circuits for ZZ2. A lot of people over the years have tried to understand how 'ZZ' works.

_{note to TOK, IMR/SER 'ZZ' really does exist.} ;D ;D

[1] for certain values of 'guaranteed'

[mandgc]

I would have thought that the principle of any Signal going to its most restrictive aspect as soon as practicable- even at the 'added' expence of installing an additional Block Joint or other equipment- was essential. Situations such as Curves,etc., No Tail Lights or Smoke or dust could restrict the following driver's view of the train ahead and a Yellow aspect in these cases could only help.

[Tom]

mrfs42 said:

Same circuit, different way of expressing it - I think. You've swapped arms

I don't think you had any wires on 2GR ^7B

[mrfs42]

tom said:

mrfs42 said:

Same circuit, different way of expressing it - I think. You've swapped arms

I don't think you had any wires on 2GR ^7B

My mind did this morning when I was rather exuberantly drunk!