RE bombers during WWII: I don't remember the movie, and of course, it was just a movie, but they showed two crew members cranking on that handle for a long time to get the gear down and locked. And, of course, gravity is assisting to lower the landing gear.
Like I said though, you can do it; you can move anything given enough leverage. You just won't move it very fast. Work is force times distance. You can decrease the force towards zero as long as you don't mind the distance going to infinity.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter