The origin of the development of the crane

The origin of the development of the crane:

In 10 BC, the ancient Roman architect Vitru had described a lifting device in his architectural manual. The machine has a mast with a pulley on the top of the pole, the position of the mast is fixed by the pulling rope, and the cable passing through the pulley is pulled by the winch to lift the heavy object. Some overweight machines can use two masts to form a herringbone shape, moving the lifting object laterally, but the amplitude is small and the operation is very difficult.

In the 15th century, Italy invented the jib crane to solve this problem. The crane has a sloping cantilever with a pulley on the top of the arm that can be lifted and rotated. However, until the 18th century, all kinds of lifting appliances used by human beings were powered by human and animal power, and they were limited in terms of lifting weight, scope of use and work efficiency.

In the middle and late 18th century, after the British Watt improved and invented the steam engine, it provided dynamic conditions for the lifting machinery. In 1805, Glen Engineer Lenny built the first steam cranes for the London Dock. In 1846, the United Kingdom changed a steam crane from the Newcastle dock to a hydraulic crane.

In the early 20th century, Europe began to use tower cranes.

The crane mainly includes a hoisting mechanism, an operating mechanism, a luffing mechanism, a slewing mechanism and a metal structure. The hoisting mechanism is the basic working mechanism of the crane. It is mostly composed of a hanging system and a winch, and also has a heavy lifting and lowering through a hydraulic system. The operating mechanism is used to vertically move heavy objects or adjust the working position of the crane, which is generally composed of an electric motor, a speed reducer, a brake and a wheel. The luffing mechanism is only equipped on the boom type crane. When the boom is raised, the amplitude is reduced, and the amplitude is increased when the arm is lowered, and the balance and the unbalanced amplitude are divided into two types. The slewing mechanism is used to rotate the boom and is composed of a driving device and a slewing bearing device. The metal structure is the skeleton of the crane, and the main bearing members such as the bridge frame, the boom frame and the door frame may be a box-shaped structure or a truss structure, or may be a web structure, and some may be used as a support beam.