Crane is a kind of lifting and handling machinery widely used in ports, workshops, electric power, construction sites and other places. The name crane is the unified title of lifting machinery. Usually, cranes are mainly truck cranes, crawler cranes and tire cranes. The use of cranes lies in lifting equipment, emergency rescue, lifting, machinery and rescue.
There is a rotating drum under the inner side of the boom, and the steel wire rope is wound on it. The wire rope passes through the pulley at the top of the next boom to pull out the last boom, and so on. When retracting, the drum reverses to retract the wire rope, and the boom retracts under its own weight. This drum is driven by a hydraulic motor, so you can see two oil pipes, but don't think of it as an oil cylinder.
In addition, there are some truck cranes with nested plunger cylinders installed inside the telescopic boom, but this application is rare. The multi-stage plunger cylinder is expensive, and the boom will bend elastically when loaded, which has a great influence on the life of the cylinder.
Oranges used to irrigate farmland in ancient China are the prototype of the jib crane. /kloc-in the 0/4th century, a jib crane driven by human and animal power appeared in western Europe. /kloc-in the early 20th century, bridge cranes appeared; The important wearing parts of cranes, such as shafts, gears and slings, began to be made of metal materials and started to be driven by water.
/kloc-In the late 20th century, steam-driven cranes gradually replaced hydraulic cranes. Since the 1920s, due to the rapid development of electrical industry and internal combustion engine industry, various cranes powered by electric motors or internal combustion engines have basically taken shape.