OK .... The verdict's in !!!
We were on the right track with many of the suggestions:
1. It was used for aerial and satellite based photography
2. It was used in a military application.
3. It's only part of a larger device /Lens
4. The 3 gears are driven by a ring gear.
It is a lens element from a Perkin-Elmer Type I Aerial Camera 36inch (916mm) f/4.0 ... Kudos to Spectral Joe on CN.
Further internet searching reveals:
It is part of a Perkin-Elmer 36inch focal length (916mm in the new money) f/4 aerial surveillance camera lens. Some history indicates that these were used on various US surevillance/spy aircraft: A-12, SR-71 and possibly also the U2 aircraft and on satellite. They recorded an image on to 9 x 18 inch film. The entire lens assembly weighs in at 200 pounds. The lens I have is 18 pounds of that.
Should be good for some sort of project. Historic pic attached.
Best
JA