Figure 12-45.-Crane capacity lost by crane out of level.1. Failure to block/crib under the outrigger padswhen poor ground conditions cannot support the totalweight of the crane and load. Proper and impropercribbing is shown in figure 12-44.2. Failure to extend the outriggers fully and usethem following the manufacturer’s instruction.3. Failure to note overhead obstructions, such asoverpasses and power lines.4. Failure to level the crane. Leveling the cranecannot be overemphasized. Cranes must be set up as permanufacturer’s instruction with the outriggers fullyextended and the crane leveled. Crane capacity is lostwhen the crane is out of level by only a few degrees (fig.12-45). Most cranes have levels mounted on them, butthe levels are not always accurate. Use a 3-foot builderslevel to check the level of the crane over the rear andover the sides (fig. 12-46).Load CapacityThe rated capacities of mobile cranes are based onboth strength and stability. Manufacturers of craneswill normally denote on the load charts a shaded area ora bold line across the chart dividing the lifting capacitiesbased on strength or stability of the crane. It isextremely important to know the difference for, in onecase, one of the structural components of the crane willbreak and, in the other case, the crane will tip over.Additionally, the following factors must berecognized and the capacity adjusted accordingly:1. Do not use stability to determine lifting capacity.Use the load chart installed by the crane manufacturer.The load chart is securely attached in the operator’s cab.2. The number of parts of line on the hoist and thesize and type of wire rope for various crane loads.3. Length of boom.4. Boom angle.5. Boom pendant angle (when the telescopic/folding gantry is down, the angle decreases and thestress increases).Figure 12-46.-Leveling procedures using a builder’s level.12-31
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