Which type of crane utilizes a revolving superstructure on a tracked or wheeled base?

The correct answer is mobile crane, which is designed to have a revolving superstructure mounted on a tracked or wheeled base. This design allows the mobile crane to be easily transported to different locations and offers the flexibility to operate in various working environments. The ability to rotate the superstructure enhances the crane's efficiency in lifting and moving loads within a large radius without the need to relocate the entire machine.

In contrast, a tower crane is typically fixed to a certain location and does not feature a wheeled or tracked base, limiting mobility. A bridge crane spans over a fixed area, operating along tracks and is ideal for lifting loads within a singular defined space, such as warehouses or factories. A fixed crane, on the other hand, is permanently installed and does not possess the revolving capabilities associated with cranes designed for mobility. This fundamental difference in design and function is why the mobile crane is correctly identified as the type utilizing a revolving superstructure.