Crane load chart

Figure 15-4. Illustrative example of a mobile crane load chart. The illustration covers only a few of the conditions important in deciding whether it is possible to make a safe lift.

The crane was properly certified, but the investigation revealed that the load chart was faded, torn, and generally unreadable. The operator had attempted to make the lift without consulting the load chart and had exceeded the radius for the load and crane configuration thus, the crane overturned. 

There are many details to know about for each kind of materials handling equipment. Also, loads on materials handling equipment must not exceed safe load limits. Operators must know how to plan a Uft and how to read a load chart. Operators must drive mobile equipment safely. Cranes should stay certain distances from power lines (see Case 12-3). 

Another control is lift planning. That helps ensure a safe load and lift. In some cases, there is a need to complete precise load calculations that account for many factors. Hoisting apparatus should have load limits clearly marked. The ratings assume a static load. Jerked loads or loads dropped some distance create dynamic conditions. They place inertial loads on the rigging and structure and may overload them. Cranes, for example, should have a load chart affixed to the operator s cab and an operator s manual in the cab. The operator must know the weight of the load. That and other information allow the operator to use the load chart and ensure the capacity of the equipment is not exceeded. 

If the operator knows all of these, the operator can make readings on the load chart unique to the crane model and can determine if the operation will be within all structural and stability limits. See Figure 15-4 for an abbreviated example of a load chart for a mobile crane. The limits assume a level machine. There are different limits when tires are not fully inflated and when the outriggers are not in place. 

Always check the crane s load chart to ensure that the crane will not be overloaded for the conditions under which it will operate. Plan lifts before starting them to ensure that they are safe. Take additional precautions and exercise extra care when operating around powerlines. 

Look at crane cab for properly marked controls, damaged instruments and for properly displayed and legible load charts. 

The working chart used during the investigation would contain much more information and detail than this simplified chart. Events and conditions would address the truck maintenance program, the qualifications and conditions of the drivers and crane operator, and obviously more detail about the models, makes, and conditions of the trucks and crane, detaUs about the load (weights and rigging, for example), and more background information about the yard and the operations. 

All movable cranes must have boom angle indicators those cranes with telescoping booms must have some means to determine boom lengths, unless the load rating is independent of the boom length. Load rating charts must be posted in the cab of cab-operated cranes. All mobile cranes do not have uniform capacities for the same boom length and radius in all directions around the chassis of the vehicle. 

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