Crane Hook Block

The hook is the most common type of spreader in lifting machinery.

Generally, forged single hooks are mainly used for lifting cranes below 30T, double hooks are used for lifting 50T-100T cranes; sheet-like single hooks are used for lifting 75T-350T cranes, and double hooks are used for lifting cranes above 100T.

The hook is often suspended on the wire rope of the hoisting mechanism by means of pulley blocks and other components.

2. Classification and selection

The single hook is simple to manufacture and easy to use, but the force is not good, and it is mostly used in the workplace with a lifting capacity of less than 80 tons;

When the lifting capacity is large, double hooks with symmetrical forces are often used.

Laminated hooks are riveted from several cut and formed steel plates. When individual plates have cracks, the entire hook will not be damaged. The safety is good, but the self-weight is large. Most of them are used for large lifting capacity or lifting molten steel buckets on the crane.

The hook is often impacted during the operation and must be made of high-quality carbon steel with good toughness.

Let's take a look at the cross-sectional shape of the hook body, which are generally round, square, trapezoidal and "T" shaped.

As for the forging of the tail of the hook, if the triangular thread is used, due to the serious stress concentration of this structure, it is easy to break at the crack, so trapezoidal or zigzag threads are mostly used at the tail of the large hook.

3. Applicable Environment:

Suitable for factories, mines, petroleum, chemical and ship terminals. Ensure safety, quality safety factor, and static load up to 3 times.

The lifting capacity is from 5 tons to 150 tons.

4. Dangerous section

The hook has three dangerous sections, and special attention should be paid during inspection.

As shown in the "Dangerous Section Diagram", the three dangerous sections of the hook are:

(1) The A-A section is affected by the tension of the sling on the one hand, and the hook has a tendency to be straightened; on the other hand, it is also affected by the bending moment.

Because the bending moment acting on this section is the largest and the bending stress it is subjected to is also the largest, so this section is a dangerous section.

(2) The B-B section is the same as the A-A section. The B-B section has a tendency to be straightened and sheared under the action of the tension of the sling, and the shear stress is the largest here, so it is also a dangerous section.

(3) C-C section this section is the thinnest part of the hook column, which tends to be broken under the action of the tension of the sling.

The tensile stress is the largest here, so it is also a dangerous section.

5. Safety inspection

(1) For hooks used in human-driven hoisting mechanisms, test with 1.5 times the rated load as the inspection load.

(2) For the hook used for the power-driven hoisting mechanism, the test shall be carried out with twice the rated load as the inspection load.

(3) After the hook is removed from the inspection load, there should be no obvious defects and deformation, and the increase of the opening should not exceed 0.25% of the original size.

(4) For hooks that pass the inspection, marks should be printed in the low-stress area of the hook, including the rated lifting weight, factory standard or factory name, inspection mark, production number, etc.

6. Scrap standard

The hook should be scrapped when one of the following conditions occurs:

① cracks;

②The wear of the dangerous section reaches 10% of the original size;

③The opening is increased by 15% compared with the original size;

④The twisting deformation of the hook body exceeds 10°;

⑤ The dangerous section of the hook or the neck of the hook has plastic deformation;

⑥The hook thread is corroded;

⑦The bushing of the hook should be replaced when the wear reaches 50% of the original size;

⑧ When the wear off the hook mandrel reaches 5% of the original size, the mandrel should be replaced.

7. Transportation

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