according to records, the first patent on tower crane for construction was issued in 19. In 195, a crane with a fixed tower and a boom appeared. In 1923, a prototype of a modern tower crane was made, and the first relatively complete modern tower crane appeared in the same year. By 193, Germany had started mass production of tower cranes and used them in construction. In 1941, the German industrial standard DIN877 about tower crane was published. The standard stipulates that the product (tm) of the hanging load (T) and the amplitude (M) should be used to express the lifting capacity of the tower crane together with the heavy moment, which also marks the official maturity of the tower crane.
as the material basis for tower crane to bear weight, exert tension and complete work requirements, its metal structure plays an important role. Generally speaking, the metal structure of tower crane is composed of boom, tower body, turntable, bearing seat, balance arm, underframe and tower tip.
the boom structure is a trolley luffing horizontal boom, and further divided into single lifting point, double lifting point and hammerhead trolley luffing horizontal boom in which the boom and the balance arm are integrated. The single lifting point is statically indeterminate, and the double lifting point is statically indeterminate. Hammer-type trolley luffing horizontal boom, installed at the top of the tower, looks like a hammer, and the tower is like a hammer handle without a spire, so it is also called flat head type. Flat-headed makes the structure simpler, more conducive to stress, reduce self-weight, simplify the structure and so on. The luffing boom of the trolley mostly adopts a regular triangle section.
the tower body structure, also called tower, is the main part of the tower crane structure. At present, all tower cranes adopt square section, and the section sizes are widely used: 1.2m×1.2m, 1.4m×1.4m, 1.6m×1.6m, 2.m×2.m；; The common dimensions of the standard section of the tower body are 2.5m and 3m. The most widely used connection methods of the standard section of the tower body are cover plate bolt connection and sleeve bolt connection, followed by socket pin shaft connection and plug plate pin shaft connection. Standard sections include integral tower standard section and assembled tower standard section. The latter has high processing precision and is difficult to manufacture, but it occupies a small area and costs less. A ladder must be set in the tower section for drivers and mechanics to get up and down. The width of the ladder should not be less than 5mm, the step spacing should not be greater than 3mm, and a retainer should be set every 5mm. When the height of the ladder is more than 1m, the ladder should be transferred in sections, and a rest platform should be added at the transfer point.
the function of the tower tip is to bear the upper load from the boom pull rope and the balance arm pull rope, and directly transfer it to the tower structure through the rotary tower, turntable, bearing seat and other structural components. There are truncated cone column, forward or backward truncated cone column, herringbone frame and diagonal support frame at the top of the jack-up tower.
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