Word-of-the-Month: Tower Crane
Tower cranes are large cranes that are used to lift heavy objects on large construction sites. They are a modern form of a balance crane that had been used for centuries. The crane is used during construction to lift steel, concrete, large tools, and a variety of other building materials.
A tower crane has five components: the base, mast (or tower), slewing unit, crane operator’s cab, and jib (or boom). The crane’s base provides the support needed for the crane and is bolted into a large concrete pad; typically measuring 30 feet x 30 feet x 4 feet and weighing 400,000 pounds. The mast achieves the height needed for the tower crane and connects to both the crane operator’s cab and slewing unit, the latter of which allows the crane to rotate. The slewing unit also attaches to the jib, which is made up of the machinery arm and counterweights and allows for the crane to lift heavy loads.
Today’s tower cranes can reach an unsupported (not tethered to any other stationary objects) height of 265 feet, have a maximum reach of 230 feet, lift a maximum of 19.8 tons, and carry a maximum of 20 tons of counterweight.
The first crane that was used for lifting heavy loads was invented by the Ancient Greeks in the late 6th century BC and evidence has been found of its use in the construction of ancient temples during this time.
Stahl is using a Hammerhead tower crane for the construction of the addition on the new dual-branded Hilton Tru / Home2 Suites hotel in downtown Minneapolis. The 41,129-square-foot, 8-story addition is being added to the southeast side of the existing 118-year-old building and is expected to be completed in the fall of 2020.