a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope
例句
用作名词 (n.)
Crevasse rescue is one of the more complicated mountaineering techniques, sometimes requiring pulley systems and multiple haul lines. 裂缝救援是一项更副复杂一些的登山技术，有时候需要滑轮组和多组拖曳绳。
美
