The you’re working with (Mobile, Tower, Crawler?) If you need help calculating rigging deducts
, is a critical document that specifies the maximum weight a crane can safely lift based on the horizontal distance between the crane's center of rotation and the center of the load. As the lifting radius increases, the crane's lifting capacity significantly decreases due to the increased leverage and tipping moment. Core Components of a Radius Chart A typical chart is structured as a grid where you cross-reference different variables to find the "Gross Capacity": Operating Radius (Horizontal Axis/Left Column): The horizontal distance from the center pin to the load's center of gravity. Boom Length (Top Row): The total extended length of the crane's arm. Boom Angle: The angle between the boom and the horizontal ground. Lower angles generally result in a larger radius and lower capacity. Gross Capacity: The total weight the crane is rated for at that specific intersection of radius and boom length. Calculating Net Capacity It is important to distinguish between "Gross Capacity" and what the crane can actually lift, known as crane radius chart
Most manufacturers provide a "range diagram" alongside the load chart. While the load chart gives you the raw numbers (capacities in pounds or kilograms), the radius chart (or range diagram) helps you visualize the following: The you’re working with (Mobile, Tower, Crawler
Find the row corresponding to the distance you need to reach. Boom Length (Top Row): The total extended length
If the load you need to lift is heavier than the number on the chart, you cannot make the lift. You either need a bigger crane, a shorter radius, or a different boom configuration.
Even experienced professionals can make errors when interpreting charts. Watch out for these pitfalls:
| Radius (ft) | 40 ft Boom | 60 ft Boom | 80 ft Boom | 100 ft Boom | |-------------|------------|------------|------------|--------------| | 10 | 50,000 lbs | 45,000 lbs | – | – | | 30 | 28,000 lbs | 25,000 lbs | 18,000 lbs | 12,000 lbs | | 50 | 10,000 lbs | 15,000 lbs | 12,000 lbs | 8,000 lbs | | 70 | – | 6,000 lbs | 7,000 lbs | 5,000 lbs |