This is usually a “rooster” sheave, a whip line, and ball. The crane manufacturer’s charts normally tell you in the general brochure what the weight per foot of the line is.Īnother item to use as a deduction is the weight of anything attached to the boom tip.

The weight of the lines is conservatively determined by taking the boom tip height multiplied by the number of parts of line and then multiplied by the weight per foot of line. To learn more about the number of parts of line, see our article here. If the total number of parts of line equipped on the crane have a capacity lower than the listed capacity of the crane, then the capacity of the number of lines governs. The number of parts of line may be a deduction to the capacity of the crane. You may only need the minimum size block, but the rental house could send a much larger block which could affect the amount of net capacity you have to use. This is especially required if you are planning on using a larger crane for smaller lifts. The weight of the block can be found in the crane load charts, but it should be requested from the crane rental house to know the exact size and weight of block that will be arriving on site. During a project, the actual rigging used and its weight needs to be summed up and deducted from the capacity listed in the load charts. When sizing a crane, the weight of rigging could be estimated from previous jobs or it could be sized and calculated if enough is known about the module.

Weight of any jib, ball, or any other item attached to the lifted load point.

Some deductions to look at that should accompany the weight of the modules are:

Therefore, when sizing a crane, one cannot just look at the heaviest module at a radius and compare it to the capacity of the crane at the matching radius. For most heavy lift crane charts, it means the gross load to be lifted below the boom tip. These load charts will state what that given capacity means. Crane load charts accompany every crane and simply put, they give the capacities of the crane at a known radius for a known configuration.

Crane capacity chart