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Meaning of arch head

arch' head"

Pronunciation: [key]
— Mach. Mach.
  1. a vertical, arc-shaped member fixed to the end of a walking beam, for supporting a chain from which a pump rod or the like is suspended in such a way as to let it rise and fall vertically.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.