A crane’s load chart is the most important resource a crane operator should know for ensuring crane safety, and for determining what a particular crane is capable of lifting. With all of the different crane manufacturers out there, it is imperative that the crane’s load chart be well understood. Whether you are operating a boom truck such as a Terex, National, Manitex, Pioneer, or Altec, a rough terrain crane such as a Grove, Link-Belt, Manitowoc, Kato, or Tadano, it is important to keep in mind that though many cranes have similarities in their load charts, they also have many differences. Ignoring these differences may lead to the overturning or structural failure of the crane.
Load Chart Explanation
- This chart illustrates the gross or rated capacities of a crane.
- The numbers on top row represent boom lengths of the crane
- The numbers in the left column represent operating radius
- Loaded boom angle (means the boom’s angle and radius is being measured with the boom loaded with the weight indicated in the chart)
- The gross capacity of this crane can be determined by either following the radius column and interesting boom length, or following the boom angle column and intersecting the radius or boom length column.
- The “Stowed jib deductions” row is what you would deduct if the jib was stowed on the base of the boom for the particular boom length.
Gross Capacity vs. Net Capacity
The capacities listed in a cranes load chart are not the actual loads that can be lifted on the hook.
The values given in the charts are “Gross Capacities” or “Rated Capacities”. The actual load the crane can lift is referred to as the “Net Capacity”. The maximum load must never exceed the crane’s Net Capacity!
The Gross Capacity must include the weight of anything and everything that is mounted or stowed on the boom of the crane or hanging from the boom tip. These are called “Capacity Deductions”.
Sample Capacity Deductions
- Weight of the main load block
- Weight of the Headache ball or overhaul ball
- Effective weight of Jib (Stowed or erected and not used)
- Weight of all hanging cable
- Weight of all rigging
- Weight of Load
Remember there are many variations, depending on the manufacturer of the crane. Make sure to understand what the manufacturer determines are capacity deductions.