Tower cranes arrive at the construction site on 10 to 12 tractor-trailer rigs. The crew uses a mobile crane to assemble the jib and the machinery section,
In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction—some were built into stone towers for
Cranes also make use of the pulley, another simple machine. Tower cranes often have more than one pulley. This helps it multiply its force to lift heavy objects
Early hoses were made from leather, which was never wholly satisfactory and was supplanted in the 19th century by natural rubber. Rubber layered on a pole or
