Cranes are common pieces of equipment on construction sites that are used to lift heavy materials, like steel and concrete, and heavy objects, such as torches and generators. The crane is supported by a heavy base that holds the mast. This leads to a gear and motor that help operate and rotate the crane. From there, several horizontal components extend out and allow for the crane to be loaded.
Because cranes are so tall, they need to be supported by a sturdy base. The base is generally bolted to a large concrete platform. This allows the mast to remain sturdy, even as it lifts variable amounts of weight to great heights. At the top of this mast, cranes have a gear and motor. This combination of equipment is called a slewing unit. Atop the slewing unit are three additional components: a horizontal jib, a machinery arm and an operator cab. The horizontal jib is the portion of the crane that carries the load and uses a trolley. The machinery arm houses the motors in the crane and also has several heavy concrete counter weights; these help to balance the machine out when it is lifting. The electronics required to control the crane are held inside of the operator cab.