Cast steel pulley with wall unevenness, many hot pitch points and narrow feeding channel is difficult to be fed by setting up a head.
铸钢皮带轮，壁厚不匀，热节点多，补缩通道狭窄，很难用设置冒口的方法给予补缩。
2
Think of the way walls get put up: a prefabricated wall before the invention of the crane and the pulley has to be pushed up by a bunch of people.
想想筑墙的方法：，在发明起重机之前，一面提前造好的的墙，由人力推起。
3
The pulley is fixedly installed on the wall, and the rope which is threaded through the pulley is connected with the lamp-socket, then the other end of the rope is connected with a fixed object.