Gravity and Newton’s third law dictates the capabilities of a crane within any particular locale. It’s therefore crucial that the operator has a detailed understanding of these lifting properties. Gross loading charts aid in this circumstance, as does an in-depth understanding of the mechanical faculties of the lifting apparatus. In the case of the latter attribute, the assembled components of the crane form an overall profile that determines lifting capabilities. The factors influencing the lifting characteristics include:
- The footprint of the crane
- Length and width of the lifting boom
- Quality of the rigging material
- Other mechanical components. This includes lattice sections in the boom and how many telescoping sections are incorporated within the design
The overall lifting capacity of our hypothetical crane is set by hydraulic power and outrigger length, by counterweight bulk and boom characteristics, mechanical assets that offset the mass of the load and allow it to be lifted without compromising the structural integrity of the crane’s framework.
In making matters that much easier when hiring a crane, manufacturers like to promote lifting capabilities, placing the figure in a place of prominence. Similarly, hiring companies follow this practice, listing the type of crane, the length of the boom and its lifting capacity in one breath. Thus, span of coverage and lifting prowess are closely matched within crane characteristic listings.
Unfortunately, the finer points of a lifting project can’t always be stated as a single figure. First of all, this integer is a maximum lifting value. A seasoned crane driver knows that there’s more to this figure than a load-limiting numerical value. In short, a handful of physical influences can affect the lifting cycle and trend lifting competence downward and away from the maximum limit. Foremost among these influences comes the angle at which the load is being moved. Preferred inclination of movement is straight up or down, directions that simplify the quoted limit. On consulting the load chart that should come with the crane, perhaps fixed in the cabin or appended as part of the hiring documentation, a user will see how the crane performs when the lift is carried out at different angles. Movement components accounted for by the chart include:
- Jib configuration
- Inclusion of telescoping sections
- Outrigger deployment
- Boom length
Plan to hire a crane that can handle all possible construction site loads as set by the work site you’re employed within. It’s a good idea to add at least ten percent to this figure as a safety margin. Finally, know the profile of the crane, its general footprint, and hire only from a company that understands the complexities associated with the interpretation of a load chart.