Classification of tower cranes
Tower crane is a commonly used lifting equipment on the construction site, also known as "tower crane", with a section of the length (high) (referred to as "standard section"), used to lift the construction of steel bar, wood, concrete, steel pipe and other construction raw materials. Tower crane is an indispensable equipment in construction site.
Classification of tower cranes:
I. According to whether there is walking mechanism A
It can be divided into mobile tower crane and fixed tower crane.
Mobile tower crane can be divided into rail type, wheel type, car type and caterpillar type according to the different walking device. The rail type tower crane is fixed on the walking bottom frame, which can run on the specially set track. It has good stability, can walk with load, and has high working efficiency, so it is widely used in construction and installation projects. Wheel type, automobile type and crawler type tower crane have no track device, easy to move, but can not carry the load to walk, poor stability.
Fixed tower crane according to the installation position of the different, and divided into two kinds of attachment jack-up and climbing, attached jack-up tower crane can rise with the building, suitable for high-rise buildings, the building structure only bear the horizontal load from the tower crane, easy to attach, but occupy the structure with more steel; The inner climbing tower is hoisted in the inside of the building (elevator shaft, stairwell) with the help of a set of brackets and lifting system. The lifting is more complicated, but the steel occupation of the structure is less, so there is no need to install the foundation, and all the dead weight and load are borne by the building.
Two, the structural characteristics of the boom
It can be divided into pitching hoisting boom (boom) and trolley hoisting boom (flat boom) tower crane.
The luffing boom tower crane does not realize luffing by lifting the boom. Its advantages are: it can give full play to the effective height of the boom, and the mechanism is simple. The disadvantage is that the minimum amplitude is limited to about 30% of the maximum amplitude, which cannot be completely close to the tower body.
The trolley variable amplitude crane tower crane is realized by walking the trolley installed on the horizontal crane track. Its advantages are: large amplitude range, the trolley can drive close to the tower, and can carry the load variable amplitude. Its disadvantages are: The crane boom has complex stress and high requirements for structure, and the crane boom and trolley must be in the upper part of the building, and the spire installation height is 15-20 meters higher than the building roof.
Three, tower structure rotation mode
It can be divided into lower rotation (tower rotation) and upper rotation (tower rotation) tower crane.
The main mechanism of slewing bearing and balance weight is set at the lower end of the tower crane. Its advantages are: the tower is subjected to less bending moment, low center of gravity, good stability and convenient installation and maintenance. The disadvantage is that the slewing bearing is required to be higher and the installation height is limited.
Rotary tower crane will swing support, balance weight, the main mechanism are set in the upper end, its advantage is that because the tower body does not swing, can simplify the lower structure of the tower body, lifting and adding joints is convenient. Disadvantages are: when the building exceeds the height of the tower, due to the influence of the balance arm, the rotation of the tower crane is limited, and the center of gravity is higher, the wind pressure increases, the pressure weight increases, so that the total weight of the whole machine increases.
4. Different installation methods of tower cranes
It can be divided into the tower crane which can be folded and transported and set up as a whole by itself and the tower crane which needs to be assembled and disassembled by auxiliary machine.
Self-erection of quick-loading tower cranes are small and medium-sized rotary tower cranes, mainly used for short construction period, the requirements of frequent movement of low-rise buildings, the main advantage is to improve work efficiency, save installation costs, save time, save labor and save materials, the disadvantage is complex structure, large maintenance.
The tower crane, which needs to be disassembled by auxiliary machine, is mainly used in middle and high-rise buildings and places with large working range and large lifting weight, and is the main machine type on construction sites.
Five, according to the structure of the spire
It can be divided into flat tower crane and pointed tower crane.
Flat head of tower crane is developed in recent years, a new type of tower crane, its characteristic is in the structure of the original self-lifting tower crane on cancelled the spire and pull rod before and after parts, enhances the big arm and the structure of the balance arm strength, big arms and balance arm directly connected, its advantage is: 1, the machine is small in size, convenient installation safety, decrease the cost of transportation and storage; 2. The derrick has good endurance, uniform force, and little damage to the structure and connection part; 3, parts design can be standardized, modular, interchangeability is strong, reduce idle equipment, improve investment efficiency, its disadvantage is in the same type of flat head tower tower slightly higher price.