Tower cranes are indispensable lifting machinery in modern construction. From administrative catering departments at all levels to industry associations, catering units, and user units, the cooking and operation of tower cranes are gradually standardized. However, there are still some issues that affect the safe operation of tower cranes at this stage, and sufficient attention needs to be given

Safety equipment such as torque limiters, component limiters, height limiters, amplitude limiters, and fly cutting maintenance devices for tower cranes have become mandatory inspections. Next, the editor of tower crane leasing will talk to you about several issues that are easily overlooked in the safe use of tower cranes:

1、 Calculation of Slope Stability of Tower

When the tower crane needs to be arranged to be stored at the edge of the building foundation trench and there is no slope protection method, it is necessary to conduct slope stability calculation. Is the small pipe placed above the foundation trench or at the bottom of the foundation trench. After the tower crane equipment is installed, the construction period is around February. During this period, if there are problems with the slope due to oscillation, rain, and other reasons, it will inevitably affect the safety of the tower crane operation

2、 Normative sections should be interspersed and applied

If the standard section of the tower crane (with the base section or reinforcement section outside) is temporarily installed inside the tower crane, it will definitely result in excessive stress and fatigue damage or damage to the standard section. The correct approach should be to cross and rotate other standard sections at the lower part every time they are disassembled and assembled, to prevent the same standard section from always being inside the tower crane. Some relevant local units did not pay attention to this point. When the tower crane was disassembled, it was at a disassembly angle. At this time, there are generally three standard sections in the frame that are not taken out, and the equipment remains the same. This shows that the above three standard sections have always been at the bottom of the tower crane, and the order will not be changed. Over time, it will definitely lead to trouble

3、 Timely replacement of connecting bolts in standard sections

Strong and legitimate property rights units attach great importance to this, while some individual units that rely on affiliations for a living have relatively more non-standard applications. If the bolts are severely corroded and the screw surface shows rust and dents, which have not been replaced and are still in use, seriously violating the requirements for high-strength connection bolts, the safety factor of the tower crane will be greatly reduced. Usually, the connecting bolts in the standard section are equipped with flat washers, and then the stress area of the connecting sleeve is increased to maintain the outer surface of the connecting sleeve from being damaged by resistance. The hardness of this flat washer is very high. Some disassembly and assembly personnel arbitrarily removed the flat washer during operation, resulting in scratches on the surface of the connecting sleeve, affecting the tightening force, increasing the local pressure of the connecting sleeve, and changing the uniform force on the connecting sleeve

4、 Check the key points of the primary nodes and welding points of the components

There are many nodes and welding points in the tower crane structure, and it is indeed difficult and unnecessary to check them all in place. It is important to do a good job in checking the connection points of the tower cap and balance arm. The main nodes and welding points of the arm components should be inspected and stored during the disassembly and assembly period or maintenance period of the tower crane. At this time, careful inspection should be conducted to fully handle the problems found; During use, make spot checks and monitoring of key points to prevent the handling of defects during use from affecting user usage and even presenting economic issues

5、 Correct welding of ground wire

The welding of tower crane ground wires is generally carried out by the welding workers organized by the application unit, but neither the equipment property unit nor the application unit has provided targeted safety skills disclosure to the welding workers, resulting in random welding of tower crane ground wires. In some cases, the ground wires are even welded to the primary load-bearing part of the tower crane, and the weight is welded to the center of the cross beam, all of which pose risks for safe operation

6、 Problems with buried cables on construction sites

The buried cables between the first level distribution box and the first level distribution reed, as well as between the first level distribution mast and the third level distribution box on the local construction site, do not use armored cables. Instead, general micro cables are directly buried, and insulation checks in a simulated wet state are not conducted before daily use in the port. The tower crane can still be used in dry weather conditions in autumn and winter, but in spring and humid conditions in multiple seasons, it may cause the tower crane to fail to operate normally and travel, resulting in resumption of work or other problems

7、 Tower crane wires and cables should be replaced in a timely manner

Almost all tower crane wires and cables are stored outdoors for outdoor operation, with rapid aging due to wind and sun exposure. The parts that are often disassembled and bent are more obvious. If they are not replaced when aging and cracking are severe, they will still be used. Every rainy day, they will experience problems such as leakage, electric shock, and tripping. Moreover, when the above-mentioned faults are caused by torque limiters or other safety equipment circuits, the operating unit is not allowed to stop the machine. In addition, the maintenance electrician, on their own or under the command of relevant personnel from the property rights unit, directly removes the safety equipment circuit (waiting for restoration in non rainy weather), artificially causing safety equipment failure. The property rights unit seems to save interest on replacing wires and cables, but in reality, it has traded for greater danger. Therefore, when the aging of tower crane wires and cables affects safe operation, it is necessary to replace them in a timely manner and avoid confusion

8、 Hook or object charged

The hook or lifting object is electrified, which occasionally occurs at the construction site. This phenomenon is usually caused by the leakage of the tower crane electrical system. Once the tower crane electrical system leaks, the relevant leakage maintenance device will act. There are two main reasons for electric shock caused by personnel taking off the crane: firstly, during welding operations, the grounding wire (exposed part) of the welding machine is inadvertently connected to the tower crane, causing it to be electrified; One reason is that the grounding wire of the tower crane has not been made or does not meet the requirements, and the maintenance zero line at the lower end of the power cable of the tower crane is not connected. This will cause the maintenance zero line to break and induce voltage when the tower crane is powered on

9、 Phenomenon of outsourcing tower companies and electricians contracting tower

Small scale tower crane property rights units or individual affiliated units excessively consider interest, coupled with a shortage of tower crane drivers and electricians, resulting in the phenomenon of outsourcing tower cranes and electricians, posing a significant risk to the safe use of tower cranes. The above mentioned companies and electricians generally have high liquidity and are not convenient to handle; The level of homework varies between good and bad, with a relatively poor sense of responsibility. Sometimes, having multiple towers or one person working continuously can easily lead to fatigue during homework. The safe use and safety management of tower cranes are dynamic and temporary, and should not be rushed for quick success. Property rights units should cultivate their own tower operators and electricians, and eliminate outsourcing tower operators and electricians

10、 Equipment overspeed maintenance equipment

During the operation of the tower crane, due to electrical or mechanical reasons, there may be contactor adhesion, eddy current brake excitation site loss, etc., which can cause the lifting mechanism to operate at an overspeed, directly threatening personal and equipment safety. If the equipment has overspeed maintenance equipment, once overspeed occurs, the braking equipment will automatically switch on, improving the safety function of the tower crane