Tower Cranes at Work

Today constructing a high rise building or structure would not be possible if without a Tower Cranes. It is driven or operated by a professional or highly trained crane operator. The operator must be alert or must be exact on what he is doing because just one false moved by him it will be disaster. The tower Crane might collapsed or might bang on the building or the structure as he moves around.

Tower cranes are a common fixture at any major construction site. They're pretty hard to miss -- they often rise hundreds of feet into the air, and can reach out just as far. The construction crew uses the tower crane to lift Steel, concrete, large tools like acetylene torches and generators, and a wide variety of other building materials.

When you look at one of these cranes, what it can do seems nearly impossible: Why doesn't it tip over? How can such a long boom lift so much weight? How is it able to grow taller as the building grows taller? If you have ever wondered about how tower cranes work, then this article is for you. In this article, you'll find out the answers to all of these questions and more!

This Tower Cranes are used to transport materials from the ground to the top most part of the building constructed or as needed to the floors constructed. This cranes made the materials transporting easier for the construction.

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.

How Much Weight Can They Lift?

   

A typical tower crane has the following specifications:

• Maximum unsupported height - 265 feet (80 meters) The crane can have a total height much greater than 265 feet if it is tied into the building as the building rises around the crane.
• Maximum reach - 230 feet (70 meters)
• Maximum lifting power - 19.8 tons (18 metric tons), 300 tonne-meters (metric ton = tonne)
• Counterweights - 20 tons (16.3 metric tons)

The maximum load that the crane can lift is 18 metric tons (39,690 pounds), but the crane cannot lift that much weight if the load is positioned at the end of the jib. The closer the load is positioned to the mast, the more weight the crane can lift safely. The 300 tonne-meter rating tells you the relationship. For example, if the operator positions the load 30 meters (100 feet) from the mast, the crane can lift a maximum of 10.1 tonnes.