North Ealing

[Deleted]

On the e/b picc between Park Royal and North Ealing, there are short sections of positive rail on the r/h side of the four foot, despite the pos. rail being to the left along here. Are these short sections of rail something to do with the signalling (perhaps train speed sensing?) due to the approaches to Hanger Lane Junction.

Thank you.

[Deleted]

I think you're right there. Ask our main in the know, SPD, for confirmation, But I think you're right.

[Deleted]

The rails can be seen in the V125 Piccadilly DEV. I think there are two of them.

I've also noticed that the repeaters are only clearing as the train approaches.

[Deleted]

Hmm, the answer may be in the speed that the train is going.... Have to re-watch the dvd at some point in the next week or so....

[agoodcuppa]

david5032 said:

Are these short sections of rail something to do with the signalling (perhaps train speed sensing?) due to the approaches to Hanger Lane Junction.

That's exactly right.

The leading r/h posy shoe has to pass over the detection rail below a predetermined speed otherwise the signal will remain at danger.

[Deleted]

Thanks for that, AGC. So I'm guessing that it works by timing how long the r/h +ve rail is energised by the train?

[bobbybrakedust]

do you mean the delta tracks (induction rail ) on the approach to the signals
there are a couple of them down there
they work by the collector shoe sliding over them and if your at the correct speed and theres nowt in front the stick should drop off
its to slow you down and get you closer to the objective

however if its broke you will smack the stick its works with
as i have found out (blushes)

[agoodcuppa]

david5032 said:

So I'm guessing that it works by timing how long the r/h +ve rail is energised by the train?

Yup, all shoes are live if one is receiving current from the juice rails so the short "delta" track uses this to measure the speed of the train.

[Deleted]

delta track circuits and inductor rails are completely different

delta tracks = a track circuit within a track circuit it injects a frequency and then the train can be detected 35ft either side of the injection point (position detector )

inductor rail = as the postive shoe runs over it by using magnets (not good on science stuff) it can work out what speed the train is doing by picking up the FR (frequency relay) and a contact in that relay is in the signal selection circuit for the signal in front so if the train is doing the correct speed the signal clears (speed control) if the train goes too fast or too slow the FR will not pick up now in this case the train has to pick up a JR (timing relay) which is either 4 1/2 secs or 15 secs this then will clear the signal its like a belt and braces thing if one part of the circuit fails due to the inductor being broken the signal can still clear

but to be honest there is only a handful of inductors that do work as getting spares is very hard to find so 7 times out of 10 the inductor will not work at all i.e WM400 (ealing common e/b home) had a inductor till i took it out of use and put it in the 6ft due to a train shoe hitting it and a faulty power pack