Is the working load of a crane the maximum weight it is able to lift?
generally the safe working load (SWL) is the max weight a crane can lift in regular operation . but for testing purpose the crane may be loaded more (1.5 times SWL or 2.00 times swl) further it depends on application of the crane. The reason being if you test the crane for higher values, it means it is safe to use within the SWL But the higher value must not cross beyond structure design load
Usually there is a safety factor of 400% built into all engineered cranes. This is to account for unforeseen momentary spike loads, operator errors and component weaknesses ( (chipped tooth or poor forged parts or chains, etc) This is to take into account shock loads, for instance if you were picking up a bundle of steel bars and the load shifted and the bars dropped a foot or so the momentary load on the crane spikes. Working load is basically the load the crane is designed to run all day long at. If you run at the design load the crane is covered under the manufacturer's guarantee against defects and the maker is liable for problems or failures associated with the crane. But for example if the manufacturer can demonstrate you were picking up a 5 ton load on a regular basis with a crane rated at 3 tons, the manufacturer's liability is negated. Since you can counterweight any crane enough to theoretically lift anything, most of the cranes that have electric motors actually will stall if you lift much over the design weight. In other words in the above crane if you try to pick up 5 tons with a 3 ton crane, the motor will not have enough horsepower to pick up the weight and the motor will simply not lift it. The actual overload factor built into a crane is usually to contend with those shock loads and defective or weak components not seen.
its very less than the actual breaking point just to be on the safe side.
yes it is , because when we Design a part usually we will ad safty factor 1.5 or more from the maximum weght is able.
Good long answer already given. Adding only that working load is for normal usage. A crane with an angled boom may be able to lift a higher load with a shorter boom (less with very long) or if the boom is kept at a higher angle so load is closer to base. This will be given in the detailed specs.
