What is point load of a crane?

Answer 1

Point loads occur when relatively high weights are concentrated on a small bearing area.

So; point load on a crane with hooks is a load that is not centered. If you try to pick something up with the end of the crane hook, the load is not centered and would be "point loaded". This type of load will stress the crane cables. When the load falls off the hook-point, the crane cables react - and can break strands of the cable.

The crane cable consists of an inner cable and outer cables - so as a load is placed on the cable, it stretches. If this load suddenly shifts or falls, the cables retract quickly and can break. This is dangerous, as you may not notice the inner cable has broke (could be a small bulge in the cable). Using the crane with a broken cable can cause it to fail and drop the load.

A stable load is one in which the center of gravity of the load is directly below the main hook and below the lowest point of attachment of the slings. The center of gravity of an object is that point at which the object will balance. The entire weight may be considered as concentrated at this point. A suspended object will always move so that the center of gravity is below the point of support. In order to make a level or stable lift, the crane or hook block must be directly above this point. Thus a load which is slung above and through the center of gravity will be stable and will not tend to topple or slide out of the slings.