a tackle that is composed of a rope passed through two fourfold blocks in such a way as to provide mechanical power in the ratio of 1 to 5 or 1 to 4, depending on whether hauling is done on the running or the standing block and without considering friction. Cf. tackle (def. 2).
FOURFOLD PURCHASE
Meaning of FOURFOLD PURCHASE in English
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012