Ask and Answer about Hoisting Machinery <2>

Ask and Answer about Hoisting Machinery <2>

1. A: What is the standard of obsolete steel wire rope?
    B: a. The amount of wire fracture exceeds 10% of total number of steel silks.
        b. There are abnormal phenomenon for steel wire ropes, such as twisting, fast knot, dog leg, squash, loose, wave shape, rope core outside or broken strand.
        c. The dimension of steel wire rope decrease 7%-10%.
        d. The abrasion or corrosion scope of the steel wire rope surface reaches over 40% dimension, the whole steel wire rope is hard obviously.

2. A: What is the standard of obsolete steel wire sling?
    B: a. The amount of wire fracture exceeds 5.
        b. Wire fracture focus on the root of lead sealing.
        c. The serious corrosion section is less than 95% of original dimension.
        d. The scale of twisting, fast knot and distort is larger than 20%.
        e. The lead pressure is blocked out.

3. A: What is the meaning of <ten tops not to lift> in jargon?
    B: a. Command signals are not clear.
        b. Oblique hanging.
        c. Weight of objects to be lifted is unknown or overload.
        d. Bulk material to be lifted is not lashed firmly or filled too full.
        e. There is anyone who is on the object to be lifted.
        f. Objects to be lifted under the ground.
        g. Safety device is out of order.
        h. Any operator who is in ill.
        i. There is no enough light so that the crane operators cannot see clear the lifting and falling point.
        j. Objects with blade edge has direct contact with steel wire rope meanwhile without enough safety measure.

4. A: What is the principle to choose the right suspension center?
    B: The first tip is to keep the stability of the objects to be lifted.
        a.Longilineal objects (such as pipe/pillar shaped material)
           If the operators adopt only one hoist point to keep the object in vertical lifting, the suspension center should be at the beginning of 1/3 of lifting end.
           If the operators adopt two hoist points to lift goods, the suspension center should be at 1/5 between both lifting ends.
           If the operators adopt three hoist points, two of suspension points should be 13% of both ends and the remain one is in the middle of the object.
        b. Square objects
            In general, as to square objects to be lifted, the operators will choose four suspension centers in symmetric to keep stable.
        c. Special objects
           Some machinery are in high installation accuracy, in this case auxiliary suspension center will be applied to keep steady. The main suspension center is always in the gravity and chain block will be used for the lifting process to make level.

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