Explain tower crane with neat sketch with respect to types, components, working suitability and factor’s affecting its performance.

The commonly used Hoisting equipments are:

• Block and Tackle.
• Winch.
• Power hoist.
• Elevators.
• Pillar crane.
• Jacks.
• Hydraulic crane
• Hydraulic lift.

Working of Tower Crane and its suitability:

• Tower cranes are used in various construction projects of high buildings, bridges, cooling towers or power plants.

• The construction of tower crane is such that it can work and then dismantled in restricted space.

• The tower has a truss structure welded from angle bars and channels.

• Tower extension pieces are available to increase the height as per requirement. Ladders are also provided inside the whole height of the tower.

• An operators cabin is provided so as to enable full view. Jib is attatched to the last highest section of the tower.

• Two sections of jib, opposite to one another, are provided, one is saddle jib and another is counter weight jib and is controlled from the hook block.

• The upper portion of the tower is fixed on the slewing head.

• These cranes are used where concentration is in a limited area.

• The tower crane configuration enables the crane to be erected close to high rise structure and its height enables its jib to swing clear of obstructions.

• The tower cranes have 360 degree slewing capability.

• Below is the diagram of Tower Crane:

Components of Tower crane are:

1. Load Line.
2. Pendant.
3. Saddle jib.
4. Counter weight.
5. Trolley.
6. Slewing ring.
7. Climbing tower.
8. Fixed tower.
9. Tower footing.

Depending upon the nature of task, tower cranes can be grouped into the following categories:

1. Stationary crane: These tower cranes are supported on foundations and their mast bolted to a fixed position steel base placed on top of the foundations and their ballast counterweight rests on the base. The height of these cranes can be increased further upto 100 m by bracing the mast with the building structure.

2. Travelling cranes: The steel base of these cranes is mounted on a travel gear, resting on rail tracks embedded in the foundation. This enables the crane to travel along the track with a load. These cranes commonly have a height not exceeding about 70 m for top slewing and about 30 m for the bottom slewing type. The tracks have a width of 4 m to 8 m.

3. Climbing Cranes: These cranes are useful where the shortage of sufficient external space around the building doe not permit the erection of other tower cranes. This crane climbs on special climbing collars that are fitted to the buildings completed structural floors.