portal crane

例句：

1. 1. Theportal crane is used to lift heavyloads from the ground.
   门架起重机用于从地面抬起重物。
2. 2. Theportal crane was designedfor lifting large objects in constructionsites.
   门架起重机是为建筑工地搬运大型物体而设计的。
3. 3. Theportal crane has apowerful motor and can lift upto 50 tons of materialat a time.
   门架起重机拥有强大的电机，一次可以搬运高达50吨的材料。