Manually handling pad-mount transformers took its toll on line crews from Canadian utilities Hydro One and Hydro Ottawa Ltd. Each time the equipment had to be installed or removed, line workers had to ...
New research suggests that a “primitive lifting machine” was in use around 150 years prior to the appearance of cranes 2,500 years ago. This early lifting machine was capable of lifting ashlar blocks ...
一些您可能无法访问的结果已被隐去。
显示无法访问的结果
反馈