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 at any given time. With all of the different crane manufacturers out there, it is imperative that the crane’s load chart be well understood.
A load chart of a crane specifies the crane’s capabilities, detailing its features and how its lift capacity varies when considering distance, angle and length.
Before a crane is rented, transported, employed or purchased, the crane chart must be consulted to determine the best crane suitable for the task at hand.
How To Use The Load Chart Of Your Crane To Determine Your Crane Load Capacity
It is pertinent to note that only load charts that are found in the equipment operation manual or posted by the manufacturer in the equipment should be used. The load charts are specific to the make, model and configuration of a specific piece of equipment, therefore any load chart do not apply to any lifting equipment.
Don’t forget to include adjustments for buckets, boom extensions, load blocks, hoisting rope and other attachments that will alter the lifting capacity of the crane or equipment used to perform the lift. For example, the weights of hooks, blocks, buckets, slings and other handling devices must be added to the load or deducted from the equipment lift capacity.
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.
How To Determine The Net Capacity Of The Crane
According to crane hunter, 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”.
- 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.
* How to use the load chart of your crane to determine your crane load capacity *
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