these pix dredge up a lot of memory's. i was involved in inspecting and buying the first operational (or so we were told) atlas f sites in Kansas. also as a f system engine tech, i spent many hours in those holes. our sites being the first operational sites we didn't have working tech manuals and we were responsible for writing ,proof testing and then sending them to the publisher. after that we went to Vandenberg in kali to instruct the instructors.
as i recall, if my fading memory isn't letting me down, those silo doors weighed in around fifty two ton each. they had four ice breaker jacks at the leading edge to (strangely enough) hammer the door and brake the ice in the winter. once the doors were opened to there vertical position the cylinder had to reverse and catch the door to park it over center. up on closing, the cyl had to draw the door over center and then reverse the pressure to catch it and let it down in sequence gently. if things went wrong the doors would slam shut really hard sending chunks of concrete into the hole . needless to say it happen.