How Tower Cranes Work

Parts of a Tower Crane

All tower cranes consist of the same basic parts:

  • The base is bolted to a large concrete pad that supports the crane.
  • The base connects to the mast (or tower), which gives the tower crane its height.
  • Attached to the top of the mast is the slewing unit -- the gear and motor -- that allows the crane to rotate:

On top of the slewing unit are three parts:


  • The long horizontal jib (or working arm), which is the portion of the crane that carries the load. A trolley runs along the jib to move the load in and out from the crane's center:
  • The shorter horizontal machinery arm, which contains the crane's motors and electronics as well as the large concrete counter weights:
  • The operator's cab:

The machinery arm contains the motor that lifts the load, along with the control electronics that drive it and the cable drum, as shown here:

The motors that drive the slewing unit are located above the unit's large gear:

Now let's find out how much weight this equipment can handle.