Rashi in several places (Gen. 41:6; Ex. 12:7, 21:25; Lev. 26:36) writes that משקוף ("lintel") is related to the Aramaic root שקף ("beat"), "because the door beats against it."
How so? Doesn't the lintel lie above the door, as in modern doorframes? (If I'm understanding correctly Rashi's description in Pesachim 94b, ד"ה אי נמי, the door's upper pivot fits into a hole in the lintel - implying that they are stacked vertically.) It wouldn't seem, then, that the door "beats against" the lintel any more than against any other part of the frame.
(Or perhaps indeed משקוף means a combination lintel-doorstop of some kind - say a piece shaped like a ר in cross-section, which would be used to prevent a pivoted door from swinging in one direction. In that case, are there indeed any known examples of such construction from Biblical times?)