Giant mixers provided wet concrete to skip hoists in vertical towers that were extended as the building rose.

The drums were lifted to the top of the building by a skip hoist where they were emptied into a surge hopper that feeds the magnetic separator and jaw crusher.

An early developmental plan was that the No. 2 up-cast airway shaft was to become the cage skip hoist, so that the coal dust would be carried out of the pit not into it.

Counsel also submitted that heading No. 84.28 confers goods that have a definite industrial application and that are generally large pieces of equipment, such as drilling derricks, passenger cage elevators and skip hoists.