Crane hook rotation often occurs without any warning. When a crane is lifting a heavy object, if the hook rotates, the wire rope between the hook and the boom pulley block will be twisted together, and the lifted object will also rotate with the hook.
Reasons for crane hook rotation
The larger the crane, the higher the lifting height, that is, the longer the wire rope between the boom top pulley and the hook, the greater the possibility of hook rotation;
It is easier for the hook to rotate when the hook wire rope is wound in odd numbers than in even numbers, and the fewer the wire ropes are wound, the greater the possibility of hook rotation;
Unbalanced load: The greater the weight of a single wire rope, the greater the possibility of hook rotation;
The smaller the shape and size of the hook assembly and the size of its pulley, the greater the possibility of hook rotation;
If the speed of operating the crane to raise and lower the hook is not stable, especially when the heavy object is off the ground, the possibility of hook rotation will increase.
Reasons for crane hook rotation
The larger the crane, the higher the lifting height, that is, the longer the wire rope between the boom top pulley and the hook, the greater the possibility of hook rotation;
It is easier for the hook to rotate when the hook wire rope is wound in odd numbers than in even numbers, and the fewer the wire ropes are wound, the greater the possibility of hook rotation;
Unbalanced load: The greater the weight of a single wire rope, the greater the possibility of hook rotation;
The smaller the shape and size of the hook assembly and the size of its pulley, the greater the possibility of hook rotation;
If the speed of operating the crane to raise and lower the hook is not stable, especially when the heavy object is off the ground, the possibility of hook rotation will increase.
What to do after the hook rotates
If the weight is not too high from the ground and the crane function allows, you can lower the weight by changing the amplitude, and then straighten the hook. If the weight has been lifted high from the ground, you can only find a way to get close to nearby buildings to straighten the hook. After the hook rotates, the torque in the wire rope must be released.
1. Stop the operation immediately: Once the hook is found to be rotating, the operator should stop the lifting operation immediately and avoid further application of the load.
2. Check the hook status: Carefully check the hook, sling and other related equipment to confirm whether there is any damage or wear.
3. Adjust the load: If possible, try to slowly adjust the load position to return the hook to its normal position.
Hook rotation will affect the construction progress, and in serious cases, it may even threaten the safety of construction site personnel and equipment, so it must be avoided.