Tower Cranes

Tower Cranes

By Rajesh Karavadia

The tower crane surpasses any other cranes in terms of versatility and utility. It comes with ideal lifting technology for any civil engineering task. This high utility equipment is used to lift steel, concrete, large tools like acetylene torches and generators and a wide variety of other building materials. A tower crane has a following features and specifications:

1. Maximum lifting power- 19.8 tons (18 metric tons), 300 tonne- meters (metric ton= tonne)

2. Maximum reach- 230 feet (70 mts)

3. Counterweights- 20 tons (16.3 metric tons)

4. Maximum unsupported height: 265 feet 80 (meters)

The tower crane is a modern form of balance crane. They offer a best combination of height and lifting capacity. This crane consists of basic parts as:

1. Base: the base is fixed to the ground that supports the crane.

2. Mast (tower): It is connected to the base and to save space and provide stability this vertical part of the crane is often mounted on large beams braced onto the completed structure. Mast gives height to the crane.

3. Slewing unit: It is attached to the top of the mast.

4. Jib: this is mounted on the slewing unit. The jib suspends the load from the trolley. The trolley motor is located on the Jib.

5. Counter Jib: this part is also mounted on the slewing unit. It carries a counter weight of concrete blocks. The hoist motor and transmissions are located on the mechanical desk on the counter Jib.

6. Operator's cabin: It is located at the top of the tower attached to the slewing unit, but can be mounted on the Jib or partway down the tower.

7. Lifting hook: using electric motors to manipulate wire rope cables through a system of sheaves operates it.

The operator works in conjunction with signaler to hook and unhook the loads. The large fraction of the tower cranes in the world is in use in Dubai.

There is great demand for this equipment. Some leading manufacturers are:

1. Liebherr: Hans Liebherr established it in 1949. The company flourished with the great success of its first mobile, easy to assemble and affordable tower cranes. This series include 17 models.

-HC series: this includes eight universal cranes from 800 to 5000 mt. they are designed for very high hook heights and very long jibs.

2. Manitowoc Crane Group: they are world leaders in construction crane industry. Potain is a brand that belongs to /Manitowoc, providing tower cranes for the building construction industry. Today Company produces 60 models from manufacturing plants in France, Germany, Italy, Portugal and China. Potain produces three families of tower cranes; the smallest cranes of Potain range are the self- erecting cranes, running from 1,0t to 7, 98 t capacity. Higher and bigger are the top slewing cranes varying from 7,98t to 64t capacity; these are also the largest custom designed special application cranes, which reach capacities of 160t.