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09
2020-07

Management requirements for daily use and maintenance of tower cranes

Time of issue: 2020-07--09 Origin       Number of views : 0
Requirements for tower crane selection: the lifting weight, lifting speed, independent height of the tower crane, maximum lifting height and other technical parameters of the tower crane within the coverage area (that is, the boom length, the minimum boom and the maximum amplitude), all need to be based on the actual construction site Circumstances and safety needs are determined. If the selected capacity is too large, it will cause a waste of resources; on the contrary, it will all bring about the problems of use and safety. 2. Requirements for tower crane operators Requirements for operators: strong sense of responsibility and good technology. Because in the process of using the tower crane, it is inevitable that various failures will occur, but the first line of operations should generally be the first-line operators on the site. If the operators can find and deal with the failures in time, this can guarantee both Safe construction can save maintenance time and facilitate management. On the contrary, it is difficult to infer. 3. Requirements for the safe use of tower cranes The safety issues of tower cranes are directly related to the construction progress and quality of the project, as well as the image, reputation and social impact of the enterprise, which are of vital importance. According to the author’s experience, the main points for the safe use of tower cranes are as follows, for reference only. The use of tower cranes should abide by the regulations and regulations issued by the national competent authority, as well as the relevant regulations in the instruction manual: the working environment temperature of the tower crane is -20~40 degrees Celsius, and the maximum working air pressure is 205N/m2. Stop using when the wind speed exceeds level 6. When installing two or more tower cranes on the same construction site, pay attention to the mutual position of the tower cranes and adopt different elevation operations to avoid collisions between the tower crane boom and balance arm; safety on the tower crane Devices, namely height, luffing, rotation, lifting weight and moment limiter, etc., the last two of which are more important. If these two items fail in the test, it will be regarded as a failure of the whole machine, because it can ensure the safety of the whole machine And prevent the tower crane from tipping over. For example, in a construction site, the torque limiter of the tower crane is not replaced if it fails, and the operator mistakenly believes that it will only lift 800-1000kg of materials daily, and there will be no danger. As a result, during the process of lifting materials, due to the construction site The ground is relatively narrow, and the operator’s sight is blocked when the object is being lifted, causing the hanging object to hang on the steel reinforcement of the building, causing the tower crane frame to shake violently, and almost a major safety accident. Fortunately, the cable operator who worked on the ground notified the operator in time and immediately Stopping processing to avoid the tower crane tipping accident. It can be seen that all safety devices on the tower crane are indispensable and must be checked frequently to ensure that all safety devices are intact, sensitive and reliable. 4. Key points of using tower crane Hoisting mechanism: The hoisting motor is generally a double-beam or three-speed motor. Overstepping operation is not allowed during use. The hoisting motor can only be used for light load or empty hook lifting at high speed. Long-term operation is not allowed at low speed. Generally, the continuous running time at low speed is not allowed to exceed 5 minutes to avoid damage to the motor due to overheating. The operating principle is light load high speed or heavy load low speed. Slewing mechanism and hydraulic coupling: The principle of correct operation of the slewing mechanism is: low gear or jog start, stop and stop before driving in reverse, and do not use reverse driving to brake. Otherwise, the reducer of the hydraulic coupling will be damaged due to excessive impact, and even the shell will be broken. At the same time, the inertial torque of the tower will be increased. Although the fluid coupling has an automatic overload protection function, it must be operated correctly to extend its life. If it is found that the rotation speed of the tower crane has slowed down significantly, it is generally because the coupling is short of oil. First, check the liquid level. If it is not enough, add oil in time. If the amount of oil is too large, it will increase the inertia force at startup and lose the safety protection effect of buffering. , It will also cause the shell to break. The normal working temperature of the fluid coupling housing should not exceed 80 degrees Celsius. The brake of the slewing mechanism is only used under the influence of wind and the parking is unstable. Under normal circumsta
09
2020-07

Basic knowledge of tower crane

Time of issue: 2020-07--09 Origin       Number of views : 0
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 dis
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