Vintage Windmill and Wind Generator Forum

I was looking at this gearbox today and noticed what looks like
marks from maybe some type of clamping marks from the machining
process can anyone confirm this? Has anyone seen this before?
Just wondering. See pic.
Kenneth

When that main frame was cast that is where the sprue was located for the hole to pour the metal.It is rough because they generally break the excess metal off and do not go to the trouble to grind it smooth.
My 10 foot spring a leak there because a air bubble formed there when the metal was poured.
i have a friend that when he overhauls one he sand blast the inside good and paint its with a tar like paint.

Thanks for the explanation Paul. I have rebuilt quite a few Aermotors
but have never seen that before. I believe this one is dated 1938.
I will double check that date.

Kenneth

You're Welcome!