Signal frames

[JR 15secs]

Can any of the signal techs explain please Liverpool St central line old signalling I was told that if you treid to clear the shunt into either of the sidings and they were occupied then you had to take a release? why not just put levers back and try again?

[Deleted]

because of a circuit called the ALR (approach lock relay) this prevents signalman/signalwoman from changing there mind as to what route the train will take so once the train is on the approach track (usually platform track) then they either take the selected route or wait for the time delay usually 60 secs to release the signal lock

btw -- im not good at explaining things thats why im not in the school ;D ;D ;D

[JR 15secs]

so that makes you a grease monkey you like fixing things getting your hands dirty

[JR 15secs]

aetearlscourt can you answer this for me so that I dont start a new thread when you attend a failure is there a proper way to tackle it such as check that the failure is still on then check inside or outside equipment I suppose it may depend on what bit of kit is failing? lets use an example Earls Court shunt EC18?

[Deleted]

first phone the signalman make sure its still failing and its a proper failure sometimes they forget to try the route in push button mode on the programme machine

if it is in a control area you would always go to the frame first make sure the signal has been selected and make sure theres no conflicting moves still in the frame then you would check everything in the room first to rule out any defective relay contacts,blown fuses e.t.c then you would go outside and check there


methinks relaydel knows earls court as EC18 does intermittently fail

[JR 15secs]

Yes I know the area I looked at the yellow peril and picked it because it's a shunt move reading things like underground news which gives signal numbers etc and looking at teletext show the location and also speaking to LU people.