Su-2 turret question

[Tokkotai]

Hi all,
Could someone possibly tell me what exactly this mechanism I have circled in the photo does in the Shkas turret on the Su-2 Soviet bomber?
Cheers,
Panagiotis.

 

[fubar57]

I'm afraid I don't have the answer but here is a line drawing of the turret I found...

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I don't have time at the moment but when I get off work in the morning I can PM you some more line drawings and detail shots if you wish.

 

[Wurger]

There is no info on what it was, IMHO that looks like the mount and protection of the gunsight. Here a couple of pics

 

[Jimbob]

very cool..