Definition And Example Of “Rated Capacity”

Definition And Example Of Rated Capacity

Rated Capacity

One of the most serious hazards that cranes present is equipment collapse caused by exceeding the crane’s rated capacity. The term “rated capacity” is defined as:

The maximum working load permitted by the manufacturer under specified working conditions. Such working conditions typically include a specific combination of factors such as equipment configuration, radii, boom length, and other parameters of use.

The combination of factors that enter into rated capacity is outlined in a load chart on the equipment. The load chart generally states the weight of the load that the crane can lift at different boom radii. The longer the radius of the lift occurs, the smaller the weight the crane can lift.

Cranes must not be operated more than their rated capacity. Some crane users believe they can safely exceed the rated capacity because the manufacturer includes a safety factor in the load chart. However, any safety factor included by the manufacturer is not intended to be treated as excess capacity. It is included because various variable worksite conditions, such as swinging of the load caused by wind or other factors, can reduce the crane’s capacity from that under ideal conditions.

To comply with the rated capacity, the weight of the load must be known. Before beginning a lift, you must determine the load weight using reliable means.

Other Manufacturer Procedures

In addition to complying with the rated capacity, the operator must comply with all other manufacturer procedures applicable to the operation of the equipment. If the manufacturer’s procedures are unavailable, procedures for the operational controls must be developed by a

qualified person. Procedures related to the capacity of the equipment must be developed and signed by a registered professional engineer familiar with the equipment.

All procedures applicable to the operation of the equipment, including rated capacities (load charts), recommended operating speeds, special hazard warnings, instructions, and operator’s manual, must be readily available in the cab at all times for use by the operator.

Operating Outside the Parameters of the Load Chart

In some cases, a user may need to operate outside the parameters of the load chart. For example, a user may need to exceed the maximum working load for a particular radius to complete a task. In such circumstances, it is essential that the user obtain prior written approval from the crane manufacturer. The approval must be on file at the job site and indicate the specific conditions under which the crane may be operated outside the load chart parameters.

Operating Within the Parameters of the Load Chart

When operating within the parameters of the load chart, it is essential that all working loads are evenly distributed across the hooks or lifting devices. Unevenly distributed loads can cause the crane to tip over. If a working load that is not evenly distributed must be lifted, special blocks or another device must be used to balance the load.

The rated capacity of a crane is the maximum working load permitted by the manufacturer under specified working conditions. The combination of factors that enter into rated capacity is outlined in a load chart on the equipment. The load chart generally states the weight of the load that the crane can lift at different boom radii. The longer the radius of the lift occurs, the smaller the weight the crane can lift.

Cranes must not be operated more than their rated capacity. Some crane users believe they can safely exceed the rated capacity because the manufacturer includes a safety factor in the load chart. However, any safety factor included by the manufacturer is not intended to be treated as excess capacity. It is included because various variable worksite conditions, such as swinging of the load caused by wind or other factors, can reduce the crane’s capacity from that under ideal conditions.

To comply with the rated capacity, the weight of the load must be known. Before beginning a lift, you must determine the load weight using reliable means.

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