Tower crane is the most commonly used du lifting equipment on construction sites. It is extended section by section (height), which is like an iron tower, and is also called a tower crane.

The function of the 　　tower crane tip is to withstand the upper load from the boom pull rope and the balance boom pull rope, and directly transmit it to the tower structure through the slewing tower, turntable, bearing and other structural components. The top of the self-elevating tower has truncated cone column type, forward or backward tilting truncated cone column type, herringbone type and diagonal brace type. All upper slewing tower cranes need to be equipped with a balance weight, whose function is to support the balance weight to form a balance moment that is opposite to the direction of the lifting moment required in the design. In addition to the counterweight, a lifting mechanism is often installed at its tail. The reason why the lifting mechanism is placed at the end of the balance arm together with the balance weight, one can play the role of partial weight distribution, and the other is to increase the distance between the rope drum and the tower tip guide wheel to facilitate the winding of the wire rope and avoid occurrence Rope disorder. The amount of balance weight is inversely proportional to the length of the balance arm, and there is a certain proportional relationship between the length of the balance arm and the length of the boom. The balance weight is considerable, light tower cranes generally require at least 3 to 4 tons, and heavy tower cranes cost nearly 30 tons.

　　Tower crane classification

　　 can be divided into: 1. Pitch and Amplitude; 2. Trolley and Amplitude.

　　 can be divided into: 1. self-elevating type; 2. non-self-elevating type.

　　 can be divided into: 1. Boom type; 2. Lower rotation type.

　　 can be divided into fixed methods: 1. track type; 2. jellyfish rack type.

　　 According to the structure of the spire, it can be divided into: 1. Flat head type; 2. Pointed head type.

　　 can be divided into: 1. mechanical automatic; 2. human control.

　　 1. According to whether there is a walking mechanism

　　 can be divided into mobile tower crane and fixed tower crane.

　　Mobile tower cranes can be divided into four types: track type, tire type, automobile type, and crawler type according to different traveling devices. The track-type tower crane tower body is fixed on the walking underframe and can run on a special track. It has good stability, can travel with load, and has high work efficiency. Therefore, it is widely used in construction and installation projects. Wheeled, car-type and crawler-type tower cranes have no track device and are easy to move, but they cannot travel with load and have poor stability. Currently, they are rarely produced.

Fixed tower cranes are divided into attached jack-up type and internal climbing type according to the different installation positions. The attached jack-up tower crane can rise as the building rises. It is suitable for high-rise buildings. The building structure is only Withstand the horizontal load transmitted by the tower crane, it is easy to attach, but the structure uses more steel; the internal climbing type tower crane is inside the building (elevator shaft, stairwell), with the help of a set of brackets and lifting systems to climb, the lifting is more complicated , But the occupied structure uses less steel, no foundation is required, and all the weight and load are borne by the building.

　　 2. The structural characteristics of the boom

　　 can be divided into pitch luffing boom (boom) and trolley luffing boom (flat boom) tower crane.

The pitch luffing jib tower crane does not achieve luffing by lifting the boom. Its advantages are: it can give full play to the effective height of the boom, the mechanism is simple, and the disadvantage is that the minimum range is limited to 30% of the maximum range. The left and right sides should not be completely close to the tower body, and the load will rise and fall with the boom during luffing.

The trolley luffing jib tower crane achieves luffing by traveling on the trolley installed on the horizontal boom track. Its advantages are: large luffing range, load trolley can approach the tower body, and load luffing. Disadvantages Yes: The force of the boom is complicated, and the structure requirements are high, and the boom and the trolley must be on the upper part of the building, and the installation height of the spire is 15-20 meters higher than the roof of the building.

　　 Three, the tower body structure rotation method

　　 can be divided into lower revolving (tower body revolving) and upper revolving (tower body not revolving) tower crane.

The lower slewing tower crane has the slewing support and the main balance weight mechanism at the lower end. Its advantages are: the tower has less bending moments, low center of gravity, good stability, easy installation and maintenance, and the disadvantage is that it requires more slewing bearings. High, the installation height is restricted.

　　The upper slewing tower crane has the slewing support, balance weight, and the main mechanism at the upper end. Its advantage is that the lower structure of the tower can be simplified and the jacking and joints can be simplified because the tower does not rotate. The disadvantage is that when the building exceeds the height of the tower, the rotation of the tower crane is restricted due to the influence of the balance arm. At the same time, the center of gravity is higher, the wind pressure increases, and the weight increases, which increases the total weight of the whole machine.

　　 Fourth, the tower crane installation method is different

　　 can be divided into quick-installation tower cranes that can be folded and transported and erected as a whole by themselves, and tower cranes that need to be assembled and disassembled with auxiliary machinery.

The quick-installed tower cranes that can be erected by themselves are all small and medium-sized lower slewing tower cranes. They are mainly used for low-rise buildings with short construction period and frequent movement. The main advantages are that they can improve work efficiency, save installation costs, and save time, labor and materials. , The disadvantage is that the structure is complex and the amount of maintenance is large. Tower cranes that need to be disassembled and assembled by auxiliary machinery are mainly used in middle and high-rise buildings and places with large working ranges and heavy lifting weights. They are currently the main types of construction sites.

　　 5. According to the structure of the spire

　　 can be divided into flat-top tower crane and pointed-top tower crane.

The flat-top tower crane is a new type of tower crane developed in recent years. Its characteristic is that the spire and its front and rear tie rods are eliminated from the original self-elevating tower crane structure, which enhances the structural strength of the boom and balance arm. , The boom and the balance arm are directly connected, and its advantages are: 1. The whole machine is small in size, convenient and safe to install, and reduces transportation and storage costs; 2. The lifting arm has good endurance and uniform force, and the structure and connection parts The damage is small; 3. The component design can be standardized, modularized, and interchangeable, reducing equipment idleness and improving investment efficiency. The disadvantage is that the price of flat-top tower cranes is slightly higher among the same type of tower cranes.