Crane pulley is a number of fixed and movable pulley bolt by the efforts and changes the direction of force of purpose. , Used, how many efforts to rope in the law, decided to use results of the pulley. Some rope pulleys, a fraction of the forces is the object and the total weight of the pulleys. Principle: when n is odd and began cable-driven pulley. When using a rope pulley add any assuming increased follow-up of three rope pulleys seconds. Such as: n = 5, you need two movable pulleys (3 + 2). Even when n, starting from a fixed pulley, then all activity gear bear has two pieces of string. Such as: n = 4, you need two movable pulleys (2 + 2).
Second, determine the required number of fixed pulleys, the principle is: a movable pulley fixed pulley. When the power does not need to change direction, even the fixed rope pulley can be reduced; change of direction is required to add a fixed pulley.
In conclusion say pulley design principles can be summarized as follows: strange move, with a move, not even sure, add some changes.
Pulling method, remember one thing: disjoint rope than in fact it is difficult to pull the pulley, as long as the owners decided, somewhat difficult to pull reel wheel-less if you are a fixed pulley. Around; on the contrary, the pulley, and then for the first time since driving pulleys if a track wheel as much as possible.