1. Develop good lifting habits and plan how to hang, lift and unload before lifting.
2. Preparation: determine the weight and center of gravity of the object to be lifted, carefully read the attached documents, and mark the lifting point and weight data. Only after the center of gravity is determined can the hook be hung in the proper position!
3. The crane operator shall be informed of the weight of the lifted object.
4. The crane hook shall be suspended vertically above the center of gravity of the object to be lifted.
5. Lifting heavy objects should not only avoid damage to the lifting objects, but also prevent damage to the rigging itself. To avoid rotation or falling, the following conditions should be observed:
a) For single leg rigging, the lifting point should be vertically above the center of gravity of the lifting object.
b) If it is a double leg sling, the lifting point should be located on both sides of the lifting object, and the lifting point should be above the center of gravity.
c) In the case of three leg and four leg rigging, the lifting point should be evenly located at the level of the center of gravity of the lifting object and above the center of gravity of the object to be lifted.
Attention must be paid to the lifting angle β (between the vertical line and the lifting leg): the larger the lifting angle, the smaller the lifting capacity. Lifting angle over 60 degrees is not allowed!
If a three leg or four leg chain sling is used to lift a non uniformly distributed lifting object, the rated load of each leg shall be calculated with the two leg lifting object with the largest lifting angle. When the inclination angle of two legs is different, the rated load of each leg should be calculated by lifting the whole lifting object with one chain.
