I was wondering about the use of the crank myself. I thought it would be used to access some secret area or something like that. So I searched through the game files for any reference of it and found the answer to be far more mundane.
You probably jammed the wheel-operated door in the control room open with some wooden boxes. From what I gathered, if you don't do this and you try to open the door from the inside, the wheel breaks off and you have to replace it with the crank. It doesn't seem to have any other use in the game.