推荐回答（3个）
无非就是牵引绳的曳引比2：1每根承重绳承重可以降低到一半，那么相同粗细的承重绳安全性就大大增加了。另外1:2曳引比的方案要丰富得多，可以选取对于水平晃动有更好控制的方案。
比如相同载重量相同速度的电梯，2:1绕法时使用7.5kW的曳引机就可以满足要求，那么1:1绕法的时候就需要至少11KW的曳引机才能满足要求。
曳引绳与轿厢运动速度之比，通俗点说，就是本曳引系统存在动滑轮。根据能量守恒的道理，省力就不会省距离，省了距离就省不了力。
扩展资料：
曳引式电梯曳引驱动关系。安装在机房的电动机与减速箱、制动器等组成曳引机，是曳引驱动的动力。曳引钢丝绳通过曳引轮一端连接轿厢，一端连接对重装置。为使井道中的轿厢与对重各自沿井道中导轨运行而不相蹭，曳引机上放置一导向轮使二者分开。
轿厢与对重装置的重力使曳引钢丝绳压紧在曳引轮槽内产生摩擦力。这样，电动机转动带动曳引轮转动，驱动钢丝绳，拖动轿厢和对重作相对运动。即轿厢上升，对重下降；对重上升，轿厢下降。于是，轿厢在井道中沿导轨上、下往复运行，电梯执行垂直运送任务。
参考资料来源：百度百科-曳引机
无非就是牵引绳的曳引比2：1每根承重绳承重可以降低到一半，那么相同粗细的承重绳安全性就大大增加了。
另外1:2曳引比的方案要丰富得多，可以选取对于水平晃动有更好控制的方案。
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