Can anyone ID this engine component?

[Letum]

It's part of a common governor system fitted to many planes that have the
prop pitch set by a system using oil pressure to move a piston in the prop
hub.

What is that large disk for?
It looks like it is attached to the manual speed control shaft.

[BadAim]

Looks to me like it's simply a wheel to adjust the governor with, notice how there is a pin on the bottom to lock it in place (and the corresponding holes in the wheel).

After actually reading the article I realize the above statement is entirely wrong and I shall now STFU

[Letum]

But it's attached to the mechanism the pilot uses to change the prop pitch.
Why would you want to lock that in place?

Would it be a maintenance thing or would it be locked in flight?

[Feuerfalke]

Check out this site:

http://www.enginehistory.org/Propell...ors/hydgov.htm

Depending on the mechanism, you probably have to lock it in place?

[Letum]

Originally Posted by Feuerfalke

Check out this site:

http://www.enginehistory.org/Propell...ors/hydgov.htm

Depending on the mechanism, you probably have to lock it in place?

yes, that is where my image is from, but it doesn't explain the purpose of the large disk.

[SlipBall]

Possibly the "pin" is actually a spring loaded ball detent, which would act like a friction to hold the selected position

[Letum]

Originally Posted by SlipBall

Possibly the "pin" is actually a spring loaded ball detent, which would act like a friction to hold the selected position

Ahhh! Now that makes sense.
That would suggest that planes with this system would, in effect, have a
limited number of prop pitch settings (as many as holes on the disk).