JB/T 7334-2016Hand chain blocks (English PDF)

4.2 Performance

4.2.7 Limit strength of whole machine

By releasing the brake, to make the tail ring limiting device work. The hand chain block shall be able to reliably bear the static tensile load, which is 2.5 times the rated capacity; meanwhile there shall be no damage.

4.2.8 Strength of whole machine

The hand chain block shall be able to reliably support a static tensile load, which is 4 times the rated capacity, for 10 minutes.

4.2.9 Lifting height

The lifting height of the hand chain block shall not be less than the specified value. It should not be greater than 12 m.

4.3 Main parts

4.3.1 Hook

When the rated capacity is not more than 25 t, the hook shall meet the requirements of JB/T 4207.1. When the rated capacity is more than 25 t, the mechanical properties and materials of the hook shall meet the requirements of GB/T 10051.1. The hook shall be able to rotate 360° on a horizontal surface. The lower hook shall be equipped with a locking device.

4.3.2 Lifting chain

The lifting chain shall meet the requirements of GB/T 30026 or GB/T 30027, OR meet the requirements of the T-type chain, which is specified in GB/T 20947.

4.3.3 Hand chain

The length of the hand chain should be equal to the lifting height of the hand chain block; however, it is allowed to be less than 200 mm shorter than the lifting height. The mechanical properties shall meet the requirements of Table 7. The connecting ring of the hand chain may be exempted from welding; however, there shall be no deformation, that affects the use under the pulling force of the ultimate working load. value of the load limit protection device shall be in the range of 1.3 ~ 1.8 times the rated capacity. At the same time, it shall ensure that the lowering load function of the hand chain block is not affected.

4.5 Safety protection

4.5.2 The hand chain block shall be equipped with a tail ring limiting device. It shall meet the requirements of 4.2.7.

5.1 Test load

The test load can adopt the direct loading method by heavy objects, OR hydraulic pressure OR other loading methods that can generate test loads.

When using the heavy object method to load, the allowable deviation of the test load is ±1%. When hydraulic pressure or other loading methods, that can generate test loads, are used, the allowable deviation of the test load is 0 ~ 10%. The heavy object loading method shall be adopted as the basis for arbitration.

5.2 Visual inspection

The visual inspection shall include whether the specifications and/or status of all important components meet the requirements, such as:

- Hand chain, chain guide, chain stop device, brake;

- All protective devices, including protective covers, tail ring restraints, etc.;

- Hook and its connecting parts;

- Lifting chains, lifting sprockets, loose pulley and their fasteners.

5.3 No-load performance test

Hang the hand chain block on the support. Pull the hand chain, by manual method, under no-load condition. Raise and lower the lower hook once, according to the test lifting height as specified in Table 4.

5.4 Light load performance test

Install the hand chain block on the test bench. According to the test load as specified in 4.2.2 AND the test lifting height as specified in Table 4, operate the measured. The turning angle of the lifting sprocket is converted by the number of loops of the hand chains. Use the electrical measurement method as the basis for arbitration.

5.7 Determination of hand pull

5.7.3 Determination by heavy weight method

When using the heavy weight method to determine, first hang the load of the rated capacity, on the hand chain block to be tested. Lift it according to the test lifting height as specified in Table 4. Then adjust the position of the lifting sprocket, so that it is at the position, where the maximum torque is applied from the lifting chain. Use hands to tighten the hand chain on the descending side.

Hang the test weight and additional weight, on the hand chain, at the lifting side.

The additional weight is 50% of the test weight. The test weight is hanging near the hand chain wheel. The additional weight is hanging at a position 200 mm from the stroke limit surface. Then let go instantly. The two weights will drop at the same time. When the additional weight is in place and stop, the test weight will drop to the lowest point, at a constant speed. At this time, the weight of the test weight is the average hand pull, Fh1. At the position of the lifting sprocket, where the minimum torque is applied from the lifting chain, repeat the above tests, to obtain the average hand pull, Fh2. The average of Fh1 and Fh2 is the average hand pull Fh.

5.8 Continuous action performance test

Place the hand chain block on the tensile test bench. Hang a load of 1.1 times the rated capacity. Drive it manually or by a similar mechanical method.

According to the test lifting heights as specified in Table 4, perform 1500 continuous lifting and lowering operations. The working cycle is lifting - stop - lowering - stop. The linear speed of the hand chain shall not exceed 20 m/min.

During the test, the load shall not touch the ground. The lifting chain and gears are allowed to be lubricated and cooled forcedly.

5.9 Limit strength test of whole machine

Use a clamp to fix the chain block on the tensile testing machine. The diameter of the clamp, at the connection with the hook, is about 1/3 of the diameter of the hook cavity. Release the brake, to make the tail ring limiting device work.

During the test, load slowly and evenly, until it reaches a load of 2.5 times the rated capacity; keep it for 1 min.

For hand chain blocks of multi-row chain type, it is allowed to use the hand chain block of single-row chain type, as an alternative test.

Note: "sqrt" is the item to be inspected. "-" is the item that may be exempted from inspection.

6.3 Type inspection

6.3.1 Type inspection shall be carried out in one of the following situations:

- When the old product is subject to trans-plant production, OR the new product is subject to type-finalization and identification;

- Where there are major changes in the structure, materials, processes of the product, which may affect performance;

- No less than once a year after normal production;

- When the production is restored after suspension for more than one year;

- Where there is a big difference between the exit-factory inspection results and the last type inspection;

- When the national quality supervision agency puts forward the request for type inspection.

6.3.2 Type inspection items are as shown in Table 8

7.1 Marking

Clear and permanent signs shall be set up at the obvious position of the hand chain block. The signs shall meet the requirements of GB/T 13306. At least the following content shall be marked on the sign:

- Product model and name;

- Basic parameters (including rated capacity and lifting height, etc.);

- Exit-factory number and date of manufacture;

- Manufacturer's name;

- Trademark (if any);

- Implemented standard number. […]