The history of lifting devices is long. Mechanisms similar to cranes were used by the ancient Greeks. The name itself comes from the German word kranich (crane). This is due to the fact that the first cranes were similar to those that are now called portal cranes. They were used for loading and unloading ships in ports. Overhead cranes came later.
History of Creation
The first mechanism, similar to a modern overhead crane, appeared at the end of the 19th century in the capital of France. It was made mostly of wood, powered by hand, and required a lot of effort to operate, but people saw its potential. Soon, cranes began to be made of all-metal, and in the 30s of the XIX century they began to be equipped with mechanical drives.
The first electric double girder overhead crane was built in Germany in 1880. He had only one electric motor, but after 10 years inThe United States has a crane with three electric drives. The evolution of these mechanisms continues to this day.
Cranes in Russia
In the USSR, the peak of crane building fell on the 70s of the XX century. At that time, about 7,000 overhead double-girder cranes were produced throughout the country per year. The development was carried out by the All-Union Research Institute of Hoisting and Transport Engineering (VNIIPTMASH). The institute was founded back in 1930 during the beginning of industrialization, but it still works. The developments of the institution were of great benefit in the development of Soviet industry.
After the collapse of the Soviet Union, the volume of industry in Russia declined sharply, and accordingly, the need for overhead cranes also decreased. However, their production remains relevant, because in recent years the industry in the country has been revived. In addition, Soviet-made cranes that have served their time must be replaced with more modern models.
Electric Double Girder Overhead Crane Device
The overall design of the overhead crane has not changed since the beginning of the production of these mechanisms. The changes concerned mainly electrics, drives and the way parts are connected. The first cranes were riveted, and subsequently welding began to be used. Crane Main Parts:
- Bridge. It consists of two span beams along which a trolley with lifting mechanisms moves.
- End beams - serve to move the crane along the tracks along the span. Connected to the bridge with bolts. Most often equippedplatforms for servicing drives.
- Crane trolley - moves the load along the crane bridge. Walks on rails located on span beams. It has lifting gear. The design of the trolley is of two types - deployed and modular or hoist scheme. In the first case, all components of the lifting device (motor, drum, gearbox, brake, etc.) are located separately from each other and connected by shafts and couplings. With a modular layout, a stationary electric hoist is installed on the trolley - a ready-made lifting mechanism assembly.
- Crane cab. Not always present, recently cranes have been massively transferred to radio control from the floor.
Support structure
The vast majority of electric double girder overhead cranes are overhead cranes. This means that the crane is placed on rails fixed along the walls of the workshop and moves along them like a train. With this design, the crane has an optimal lifting height. In addition, the crane tracks can withstand a large load, which can significantly increase the load capacity. With the support structure of the crane under it, more free space remains in the span, which is important when installing high- altitude equipment in the workshop.
Suspended version
A much rarer occurrence is the overhead double-girder overhead crane. It loses to the reference in all the main parameters and the overall reliability of the structure. As a rule, such cranes are made with a lifting capacity of not more than 20tons. Support cranes can lift both 300 and 500 tons of cargo. The only advantage of an overhead double girder crane is the ability to extend the hoist beyond the span width.
Atomic cranes
Another category worth highlighting is polar cranes or circular action cranes. These are real monsters among lifting machines. The average carrying capacity is 350-400 tons, the purpose is the installation and maintenance of reactors at nuclear power plants. Such overhead double girder cranes are made with special care and pass through a multi-stage control system. The price of such a giant sometimes exceeds a billion rubles. The design feature of polar cranes is that they travel along looped tracks inside the nuclear reactor building, while all other overhead double-girder cranes move in a straight line.
Assignment of faucets
The design of double girder overhead cranes varies depending on the purpose. Basically, the load-handling body undergoes changes. The following types are distinguished:
- Hook crane - cast-iron hooks are used to grab the load, on which slings are put on. This type of crane is the most common, as it is capable of lifting a wide variety of loads.
- Grab crane. As a load-handling device, a kind of “claw” (grab) is used, which consists either of several narrow paws, or of two buckets connected to each other. The first type of grab is used when moving scrap metal, lumber and other similarmaterials, the second type - to capture bulk cargo (sand, gravel, etc.).
- Magnetic crane - equipped with an electromagnet. Mainly used for handling metal sheets.
- Foundry taps. They are used in the metallurgical industry and have many varieties - pratzen crane, muldo-magnetic, well, etc. Depending on the purpose, they are equipped with various devices for lifting loads.
The stacker crane differs significantly in design from other types. For all other cranes, the lifting body is raised and lowered using a steel cable passed through a system of pulleys. The stacker is equipped with a rigid metal mast with forks at the end. With the help of them, he captures the cargo, which is on euro pallets. Such cranes are used in warehouses
Special mention should be made of explosion-proof equipment that is supplied to explosive industries: oil and gas refineries, chemical industry enterprises and fertilizer factories. The electrics and drives of such overhead double-girder cranes are carried out in a special explosion-proof shell. When sparking inside and detonating an explosive atmosphere, such a shell will extinguish the energy of the explosion and prevent it from spreading outward. A possible explosion in the room will be prevented.
