Combination of signals in "2-12 Aheim"

[Herman]

Hello, in @Roter Brummer 's splendid module "2-12 Aheim" I saw this combination of signals. Can someone give an explanation why an how such combination is used ? The contact of the "Formsperrsignal" immediately after the contact of the main signal.
Hallo, im @Roter Brummer splendid Modul „2-12 Aheim“ habe ich diese Kombination von Signalen gesehen. Kann jemand erklären, warum und wie eine solche Kombination verwendet wird? Der Kontakt des „Formsperrsignals“ erfolgt direct nach dem Kontakt des Hauptsignals.

Regards, Herman

Bearbeitet 9. Mai 2023 von Herman
typo

[Goetz]

Hello Herman,

vor einer Stunde schrieb Herman:

why an how such combination is used ?

The combination is used, when journeys and shunting operations both start from this location.

The winged signal gives clearance for the route to the next destination.
The black signal in front gives clearance for a shunting operation.

The black signal is the stronger one of the two.
Which is why it must be switched to "go" (= Sh1) in both cases, whereas the winged signal only switches to "go" (Hp1 or Hp2) when an entire route is clear and protected.

The end of the range for shunting operations is often marked by a sign with the name Ra10, looking like this:

The shunting range must end before the entry signal for oncoming traffic, for obvious reasons.

Modern signals combine all aspects in one signal.
Here is a main signal displaying "Sh1" for a shunting operation:

note the similarity of the diagonal line, which the two white dots form, with the diagonal black bar from the old semaphore signalling the same aspect.

Kind regards
Goetz

Bearbeitet 9. Mai 2023 von Goetz
Ergänzungen

[Herman]

Thank you @Goetz for the explanation. I learned again. 
Regards, Herman

[simonjackson1964]

Supplementary question: If the shunt signal goes to SH1 the main signal stays ah HP0, but if the main signal goes to HP1, are you saying that the shunt signal has to change as well? From what i remember that certainly isn't UK practice with Semaphore signals on preserved lines where they are still in use. Of course German practice could well be different, but the interlocking would mean that the shunt signal would need to be pulled first which could potentially confuse a driver who might set off down the line before the min signal is pulled without the token and then stop at the shunt limit.

It makes more sense that if either signal is cleared the other can be ignored...?

[Goetz]

vor einer Stunde schrieb simonjackson1964:

if the main signal goes to HP1, are you saying that the shunt signal has to change as well?

Yes.
It's not a "shunt" signal. It's a "Sperrsignal". A blocking signal. An absolute "you shall not pass!".

The aspect name "Sh" stands for "Schutzhalt" and may be loosely translated to "safety halt". It is in no way related to "shunt".

For route clearance, the main semaphore is pulled first, alerting the driver to the fact that the entire route is now clear and secured. The Sh signal is pulled second, signalling that passing this signal is no longer prohibited.

Bearbeitet 9. Mai 2023 von Goetz
amendments and corrections

[simonjackson1964]

So there's no interlock between the two then? I see....

And now I have a weird image in my head of Gandalf as a pointy hatted signal saying "YOU SHALL NOT PASS!" to a smoke and steam belching locomotive Balrog...

 

Incidentally, Gandalf would make a terrible driving instructor!

[Goetz]

vor 4 Minuten schrieb simonjackson1964:

now I have a weird image in my head

I'm glad it worked   

[simonjackson1964]

594B3EC2-7A0F-4549-B947-186D6897860D

Hee hee!

[Goetz]

love it!