Cranes are equipments used in construction works. They are also commonly used in loading and unloading heavy materials. Tower crane is the most famous one, commonly found on big construction site and are very easy to recognize: they are often tens meters high. The crane is most of the time used to lift steel, concrete, large tools such as power generators and other building materials.
Cranes are one of the first equipment used in the construction industry and it seems to have been first used in ancient Greece. At the time it was powered by men or animals. The crane had a long wooden beam called arrow, connected to a rotating base. The wheel turned helped by a rope around a drum. The cable was attached to a pulley above the arrow and a hook lifted the weight.
During the Middle Ages cranes were used to build cathedrals of Europe and for loading and unloading ships in ports. During this period the bow was added to the structure. It has improved the deflection of the crane, with the possibility to rotate. Streets were narrow and it became a great advantage in Europe was to use a crane.
The first mechanical crane appeared in the nineteenth century. It was driven by a steam engine and remained in use for several years; some models were still few years ago.
In 1908 Julius Wolff Maschinenfabrik & Co. produced the first tower cranes and 10,000 units were sold. In 1949 Hans Liebherr realized that there were no cranes on the market. That's how the famous TK-10 was manufacture.
Cranes have a combination of modern combustion hydraulic systems and internal that increases the lifting of weights. The hydraulic system is based on a simple concept: a highly efficient transmission of strengths from one point to another takes place through a fluid. Most of the hydraulic machines use some kind of incompressible fluid, to be used to its maximum density.
Different types of Crane
There are 2 main aspects to consider when designing a crane: the lifting capacity and the stability: Lifting capacity depends on the leveler's strength, the pulley and the hydraulic system. In addition there are two switches that the operator can use to make sure not to overload the crane.
There are different types of cranes, each manufactured to a specific use:
Tower crane is the first to be mentioned when talking about cranes. It does not have a rolling basis. Usually used for building's construction: it is the highest for that type of work. It must be assembled piece by piece. The base is like a high scale and the arm is perpendicular to the base.
Bridge cranes: often used in factories for lifting and guiding heavy pieces of metal or material with a cable mounted on a rail.
Mobile crane: It only has one telescopic steel arm, mounted on a mobile platform. A hook is generally suspended from the boom. The cranes can also be mounted on trucks.
Cranes have been improved, simplifying the processes related to construction. They have made it safer and easier to move large and heavy loads reducing the human effort.