The Hook of Crane Structure, Material and Usage Notes

The hook is the main component of the crane. It not only bears the weight of the object, but also bears the impact load generated during lifting and braking. Therefore, the hook material should have high mechanical strength and impact toughness.

Common hooks include single hooks and double hooks. According to the manufacturing process, they can be divided into forged hooks and plate hooks. The former is generally forged with steels such as 20SiMn and 36Mn2Si, while the latter is formed by overlapping and riveting multiple cut steel plates, usually adopting 20# steel and 16Mn steel.

The plate hook has the advantages of convenient manufacturing, which can evenly transmit the load to each steel plate, and all steel plates will not break at the same time, so its working reliability is higher than that of the forged hook. However, its geometric size is large, which is suitable for cranes with large lifting capacity.

Once the hook breaks during use, it will cause personal and equipment accidents. Therefore, great attention must be paid to inspection during use. Check whether the hook body has cracks with a magnifying glass. If cracks are found, stop using it immediately.

The dangerous section of the hook is the part with large bending stress. The bending moment here is large, and grooves often appear due to the friction of the steel wire rope. When the wear of the dangerous section reaches 10% of the original height, the hook shall be scrapped. It is absolutely not allowed to continue using it after repair welding with welding rods.

All hooks have undergone strict inspection before leaving the factory, and there is a nameplate indicating the load capacity on them. If there is no mark of load capacity, it shall not be used casually. It is necessary to calculate to determine its safe load capacity, and conduct a load test with 1.25 times of this safe load capacity as the benchmark. It can be used only after checking that there is no permanent deformation, crack or other phenomena in the test. For frequently used hooks, always check for permanent deformation and wear.

When the hook is in use, it shall be equipped with a safety device to prevent unhooking.