Polar crane

• 回转式吊车

polar crane的用法和样例：

例句

1. If the site is small, it may be commanded by a gantry crane.
   假如场地小，则可采用龙门式吊车进行操作。
2. One difficulty in every building for heavy industry is the arrangement of the supports for an overhead crane.
   重工业的所有厂房均存在一个困难问题，即如何布置桥式吊车的支承结构。