Why Does The Double Girder Crane Hook Rotate?
May 24, 2023
Why does the Double Girder Crane Hook rotate?
Sometimes there is such a situation that when the double-girder bridge crane hooks the object, the hook will rotate unconsciously, so that the galvanized steel wire rope wound between the hook and the top pulley of the heavy arm will be twisted together. , the hoisted object is also rotated together with the hook.
But at this time, it is no longer possible to continue hoisting or lowering the hoisted objects.
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 personnel and equipment, so it must be avoided.
The reason for the rotation of the hook of the double girder bridge crane
1. For large and medium-sized double-girder bridge cranes, the higher the hoist, the longer the galvanized steel wire rope between the top pulley of the boom and the hook, and the greater the probability of the hook rotating.
2. The hook rotation is also related to the total number of pairs that the hook galvanized steel wire rope is wound into. 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 hook rotation.
3. The greater the net weight borne by a single galvanized steel wire rope, the greater the probability of the hook rotating.
4. The size of the hook parts and the size of the movable pulley also have an impact on it. The smaller the size, the greater the probability of the hook rotating.
5. The speed of the lifting hook of the actual operation crane is unstable, especially when the hanging object is far from the ground, the probability of the hook rotation increases.
6. The influence of some external force factors such as manpower or wind speed in the lifting process promotes the rotation of the hook, and the driver's operation is unstable, causing the hook to rotate due to the shaking of the hook and the hanging object.
7. The threading method of the hook leads to the unbalance of the hook and the rotation of the hook.
The Solution of 50 Ton Overhead Crane Hook Rotation
1. If the object of the double-girder bridge crane is not high from the ground, you can use the lifting method to solve it. After the object is put down, turn the hook back.
2. If the object on the double-girder bridge crane is higher than the ground, it is necessary to find a way to approach the nearby buildings at this time, or use other cranes to lift people back to rotate the hook.
3. If the hook rotates, be sure to remember to untie the knot in the galvanized steel wire rope. So how do you actually do it?
Put the hook on the ground, release the fixed end of the galvanized steel wire rope, rotate the tail end of the galvanized steel wire rope in the opposite direction of the twist direction of the galvanized steel wire rope to release the torque, and then install the fixed end . Finally, raise the boom of the double-girder bridge crane to a larger elevation angle, and then repeatedly lift and lower the hook to check the effect. It can be repeated several times until the hook is stable.
Preventive Measures for Hook Rotation of Double Girder Bridge Crane
1. When using a hook with several movable pulleys, try to use the movable pulley on the outer side together with the movable pulley on the boom;
2. When the hoist has several hooks, try to use the movable pulley with a large diameter;
3. Use an even number of galvanized steel wire ropes as much as possible; use as many ropes as possible when the standard allows, so as to reduce the bearing capacity of a single rope;
4. When threading and winding the galvanized steel wire rope, the movable pulley of the top section of the heavy boom and the movable pulley of the hook do not need to be separated too much, so as to reduce the horizontal rotational force caused by the galvanized steel wire rope to the hook when lifting and lowering the hook;
5. During the whole lifting process, try to reduce the length of the galvanized steel wire rope between the boom top 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 and width are relatively high, and the hook does not need to be rotated when it is in place, the hook can be locked;
7. When hoisting, the driver's operation must be stable, and the lifting and lowering hooks and rotation actions must not be carried out at the same time;
8. When purchasing galvanized steel wire ropes, try to choose "non-rotating" galvanized steel wire ropes when other standards are met;
9. After the galvanized steel wire rope of the double-girder bridge crane has been used for a period of time, it should be wound again or the fixed end should be released to release the torque in the rope.
