Gantry crane

electric gantry crane are a type of crane built atop a gantry, which is a structure used to straddle an object or workspace. They are also called portal cranes, the "portal" being the empty space straddled by the gantry. The terms gantry crane and overhead crane (or bridge crane) are often used interchangeably, as both types of overhead crane company straddle their workload. The usual distinction drawn between the two is that with gantry cranes, the entire structure (including gantry) is usually wheeled (often on rails)