Industrial cranes are vertical lifting and horizontal moving heavy lifting machines in a certain range, which is also known as overhead travelling cranes or eot cranes. It belongs to the material handling machinery. Overhead cranes are widely used in indoor and outdoor warehouses, factories, wharves and open yard.
In ancient China, the orange is used for irrigating farmland, which is the prototype of the boom crane. In Fourteenth Century, a rotary boom crane was driven by manpower and animal power in Western Europe. In the early nineteenth Century, a bridge crane appeared, and the important wear parts of the eot crane, such as shaft, gear and hoist, began to be made of metal materials and started to adopt waterpower to drive.
In the late nineteenth Century, steam driven cranes gradually replaced hydraulic powered cranes. Since the 1920s, because of the rapid development of the electrical and internal combustion engines, various overhead cranes are with motor or internal combustion engines as power devices.
The working characteristic of the bridge hoist crane is to do intermittent movement. That is to say, in a working cycle, the corresponding mechanism of fetching, transporting and unloading is alternately working. The eot cranes mainly include lifting mechanism, operation mechanism and metal structure. Lifting mechanism is the basic working mechanism of overhead cranes. They are mostly made up of suspension system and trolley, and also others use the hydraulic system to lift heavy objects.