Reasons And Solutions For Hook Rotation Of Double-girder Bridge Crane

Reasons and solutions for hook rotation of double-girder bridge crane

 

Sometimes there is a situation where when the hook of a double-girder bridge crane is lifting something, the hook will rotate unconsciously, causing the galvanized steel wire rope wrapped between the hook and the top pulley of the heavy arm to become entangled. , the hoisted objects also rotate together with the hook.

 

But at this time, it is no longer possible to hoist it again or learn to put down the hoisted object. The rotation of the hook of the double-girder bridge crane will not only affect the normal operation of the hoisting, but also seriously threaten the safety of personnel and equipment, so its occurrence must be avoided.

 

 

Double girder bridge crane hook rotation due to

 

1. The larger the double-girder bridge crane, the higher its lifting value, so the longer the galvanized steel wire rope between the boom pulley and the hook, the greater the possibility of the hook rotating.

 

2. The rotation of the hook is also related to the number of pairs of galvanized steel wire ropes wound on the hook. Generally, odd-numbered pairs are easier to rotate the hook than even-numbered pairs, and the smaller the number of pairs of wire ropes, the greater the probability of the hook rotating.

 

3. The greater the net weight carried by a single galvanized steel wire rope, the greater the probability of the hook rotating.

 

4. The size of the hook component and the specification of the moving pulley are also harmful to it. The smaller the specification, the greater the probability of the hook rotating.

 

5. The speed of the lifting hook of the crane during actual operation is unstable, especially when the hoisted object is away from the ground, the probability of the hook rotating increases.

 

6. The influence of some external factors such as human resources or wind speed during the lifting process promotes the rotation of the hook. The driver's unstable operation causes the hook and the hanging object to shake, causing the hook to rotate.

 

7. The threading method of the hook causes the hook to be unbalanced and cause the hook to rotate, etc.

 

 

Solution for double girder bridge crane hook rotation

 

1. If the double-girder bridge crane is not high above the ground or the stability is strong, it can be solved by lifting. After the object is put down, the hook can be straightened back.

 

2. If the object on the double-girder bridge crane is relatively high from the ground, you need to find a way to get closer to the nearby building, or use other cranes to lift people back to straighten the hook.

 

3. If the hook rotates, be sure to remove the knot in the galvanized steel wire rope. So, how to actually do it?

 

Put the hook on the ground, lift the fixed end of the steel wire rope, rotate the tail end of the steel wire rope in the opposite direction of the twist direction of the steel wire rope strands to release the torque, and then install the fixed end . Finally, raise the boom of the double-girder bridge crane to a maximum elevation angle, and then repeatedly lift and lower the hook to check the effect. You can repeat the process several times until the hook is stable.

 

 

Preventive measures for 25 ton double-girder bridge crane hook rotation

 

1. When using a hook with several movable pulleys, try to use the outer movable pulley together with the movable pulley on the heavy arm;

 

2. When the crane has several hooks, the moving pulley with a large diameter should be used as much as possible;

 

3. Use an even number of pieces of galvanized steel wire rope as much as possible; use as many pieces as possible when the standard allows, to reduce the bearing capacity of a single piece;

 

4. When threading the galvanized steel wire rope, the moving pulley of the boom top section and the moving pulley of the hook should not be too far apart to reduce the horizontal rotational force caused by the galvanized steel wire rope on the hook when lifting the hook;

 

5. During the lifting process, try to shorten the length of the galvanized steel wire rope between the top of the heavy arm and the hook, such as using a larger span;

 

6. When lifting, use a slip rope to make the lifting controllable. If the lifting height-to-width ratio is high and the hook does not need to rotate when it is in place, the hook can be locked;

 

7. When lifting, the driver's operation must be stable, and the lifting hook and rotation movements must not be carried out at the same time;

 

8. When purchasing galvanized steel wire rope, when other standards are met, try to choose "non-rotating" galvanized steel wire rope;

 

9. After the galvanized steel wire rope of the double-girder bridge crane has been used for a period of time, it should be re-threaded or the fixed end should be released to release the torque in the rope.