Determining the Crane Load Capacity

There are many things that are important for a construction project. While having the best equipment is essential, you must also consider the calculations that play a role. One of the biggest calculations to consider is the crane load capacity. Determining the crane load capacity ensures a safe work environment and an efficient job well done. You may need to find the Crane Capacity index for the load chart. To calculate the crane capacity index, use this formula:

(Average (radius x max (lifting height x capacity)))/100

Dimensions and Weight

First, the load chart shows the crane dimensions including the data for the outriggers, transport weight, and steering dimensions. This is important if working in a tight space since the lifting capacity depends on the use of the outriggers. Also, the transport weight determines the trailer used, how to load the crane onto the trailer, the route to take, and which permits to have for the job. When looking at the load chart, the first number along the top axis is the gross vehicle weight. The other two columns indicate the weight load for each axle.

Lift Capacity

This calculates the total lift capacity of the crane. The legend on the chart shows the specific lift the crane needs to do. To graph out the lift, the feet on the left axis represents the radius or the distance from the center pin to the center of the load. Remember to always measure the maximum capacity by the shortest lift. This is usually over the rear of the crane with the outriggers fully extended.

Lift Range

This is just as important to calculate as the lift capacity. A range diagram typically includes lift charts to illustrate how much boom length is necessary to lift loads at any distance and height.

Lift Angle

The lift angle is the maximum lift if using a luffing or fixed jib. Generally, the higher the angles of the lift, the maximum load capacity decreases. With luffing jibs, the angle automatically adjusts from the operator’s cab. However, fixed jibs have fixed angles.

Crane in Motion

Just as it sounds, this refers to the pick and carry of the crane. The load chart illustrates the total weight picked up at a 360-degree angle while stationary. The total weight can support both the rolling load at a zero-degree angle and the total weight while moving.

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