Due to the particularity and structure of the tower crane, its safety concealment exists in many factors such as installation, use, management, natural environment and so on.

　　(1) The structure of the tower crane itself

　　The rigidity, stability and strength of the tower crane steel structure directly affect the safety of the tower crane. Because the crane is subjected to frequent alternating loads during the operation, it is very easy for the steel structure friends to fatigue and break the maple. For example, cracking of the welding seam of the tower crane web, fracture, deformation, and bending of the base material reduce the rigidity, stability, and strength of the structure, cause the steel structure to break thinly, and destroy the local stability of the steel structure. Introduce friends accident.

　　(2) The quality of electrical systems and institutions

　　The working mechanism of the tower crane adopts electrical movement and control. The advantages are convenient control, saving cost and low cost. At the same time, electrical components are easy to achieve standardization and generalization, easy to replace and maintain, and easy to realize various safety protections. The working state of the electrical system of the organization determines the reliability, safety and performance of the tower crane. If there is damage or abnormality. It may cause an accident. If the electrical system fails, it can cause shock vibration of the mechanism, resulting in broken shafts and broken teeth and attracting friends. Damaged clutches or brakes or vector control may cause crashes and heavy objects. Aging electrical insulation or broken cabinets may cause electric shock. The failure of various safety devices may lead to accidents such as falling towers, folding arms and falling heavy objects. If the amplitude limit or travel limit is invalid, it may cause a big car or a small car to rush and even derail. The overload limiter and torque limiter fail, and the arm and tower may fall.

　　The failure of the height limiter may cause the wire rope to overwrap into broken rope and fall accidents of heavy objects. Phase sequence protection vector rescue, in the case of wrong phase and broken phase. It may cause disorder of operation instructions and cause accidents.

　　(3) Human factors

　　In many tower crane accidents. Most accidents are due to user violations or misuses. The two accidents mentioned below also have elements of illegal operations.

　　A non-driver of a certain unit does not ring the bell to drive. As a result, the extravagant workers on the track were crushed. When the installation team of a machinery construction company inspected the TQSOB tower crane, in order to replace the boom puller, it was prepared to remove the balance weight first and then replace the pull plate pin to connect the boom and the lifting rope together , And then use the car to lift the boom. Open the boom pull plate pin. When lowering the boom, the backward tilting moment due to the balance weight is very large, causing the tower crane to lose its balance and causing the balance arm and the tower tip to fall together.

　　Accident during disassembly. Due to the high weight of the metal structure of the tower body, the disassembly and assembly of the tower crane is a high-altitude operation, which is dangerous and technical. Among the tower crane accidents, the accidents during the disassembly and assembly account for a considerable proportion, and they are relatively large accidents. Some tower cranes are not disassembled by professional installation teams but by non-professionals. Due to the low quality of the installation personnel, the ability to prepare installation plans, the ability to select schemes and mechanical calculations, and the ability to formulate scientific disassembly and assembly, so that new problems or special problems in the operation process cannot be solved, something happened

　　is inevitable. The quality of some installations is substandard, leaving hidden dangers.

　　Improper management. Insufficient training of the staff, insufficient understanding and implementation of various rules and regulations, and insufficient management of the work site have all laid hidden dangers for the accident. Some enterprises have unsound systems and staff have no rules to follow, so they have to rely on personal experience to operate and are prone to making mistakes. Some enterprises do not implement special personnel planes. In addition, different factory models have different operation handles. Therefore, it is possible for the driver to make mistakes; some work sites temporarily combine some staff for work needs, making it difficult for the commander, driver, and rigger to achieve

　　The industry is coordinated, and some non-professionals or leaders temporarily act as operating personnel, which will inevitably lead to errors and accidents; some companies do not pay attention to maintenance management and fail to eliminate the hidden dangers of accidents in the bud.

　　(4) Natural factors

　　The so-called ugliness of natural causes refers to the unpredictable and sudden harm of Gangsuo, which does not use human will as a transfer, and some are irresistible disasters. Like earthquakes, floods, typhoons. Can be connected or indirectly caused by Guangdong. For example, in the manufacturing process of tower cranes, the residual internal stress of the structural parts is too large. During use, the local stress of the structure is greatly increased under the action of external forces, and the components suddenly break, resulting in accidents, which are also unpredictable to users. There are also tower cranes made of ordinary structural steel that operate below minus 20 degrees Celsius, which can cause brittle fracture and cause stress

　　The component is broken. The power supply voltage of the power grid is too low, and the system voltage drop is too large, causing electrical control failure, resulting in accidents caused by out of control of the organization.

　　There are other factors that may also cause accidents. For example, the safety distance between the tower crane and the high-voltage line or nearby buildings may be insufficient, which may cause electric shock or collision accidents.

　　The tower crane's foundation has insufficient pressure, which can cause the foundation to become unstable and cause tower collapse accidents.

　　Unreasonable lashing or unfavorable hanging will cause heavy objects to fall. The safety protection measures of the guard ring, guardrail and safety platform of the tower crane do not meet the requirements and may cause a person to fall. The above factors are the cause of the accident. Only by following the regulations and strengthening the maintenance of the equipment can we eliminate hidden dangers and ensure safe production.