The first cranes that were akin to today’s modern cranes were predicted to have been built in the 6th century. But as technology and safety measures have advanced over the centuries, the need to know how much a crane can lift has increased. That’s where load charts come in.

Crane load charts are diagrams that specify how much weight a crane can safely lift in certain configurations and at each radius.

Load charts are important to prevent crane overloading and cranes from tipping over.

How to read a crane load chart

Every crane load chart could be different. Each manufacturer has their own style of load charts, but the charts for each crane category will also be different.

So, we’ll cover the load charts for three types of lifting machinery.

• Tower cranes
• Mobile cranes (All-terrain cranes)
• Telehandler cranes

Crane load charts often contain these key pieces of information, either within the chart itself or the manufacturer’s manual that the chart is in:

• Crane make
• Model
• Serial number
• Year of manufacture
• Crane configuration options
• Lifting capacities at those configurations

Before you refer to any crane load chart, you first need to know what type of crane you’re operating and what configuration it is in.

Tower Crane

Above is an example of a tower crane load chart.

Before referring to it, the crane operator must know:

         1) the length of their crane jib.

         2) how many falls of rope go to and from the hook block.

The more falls of rope there are, the higher the crane’s lifting capacity will be.

To give an example, below is an image of a crane hook with four falls of rope. This same crane will be able to lift less weight with a single fall (single whip).

Once this information is determined, the operator knows what section of the load chart to refer to.

Let’s demonstrate with the bottom section of the above load chart.

Let’s say our slinger, crane supervisor, or AP asks us how much the crane will lift at 40m radius.

We know the crane hook has three falls of rope. Let’s say the crane we’re operating has a 55m jib. We look down the left column until we reach 55. Then we look across the top radius row until we reach 40. We then follow the respective column and row until they meet at 50.05. We now know that the crane we’re operating will lift 50.05t within a 40m radius. The radius is the distance between the centre of the crane’s mast and the hook block.

If we look at the figure above the hook block image, we also know that the maximum weight the crane is able to lift is 66t. But on all cranes, the maximum weight can only be lifted to a certain radius. The image shows that 66t can only be lifted as far as 30m radius. After that, the lifting capacity reduces. But the figures in the top radius column are rounded numbers. They’re not exact. This is where the next diagram comes in.

If we follow our 55m jib length row right the way over to the table on the far right, we know that 30.79m is precisely the furthest radius that we can lift our maximum weight of 66t.

Watch this in-cab footage of a tower crane load chart explanation.

Mobile Crane

Much like with tower cranes, before a crane operator reads a mobile crane load chart, they must know what configuration the crane is in. For example, there can be different sized hook blocks to choose from. And the bigger the hook block, the more falls of rope pass through it.

Let’s take a look at this hook chart to get a clear understanding.

The hook block weights are on the right and the respective lifting capacities of those hooks are on the left.

So, starting from the bottom up, a 250kg block can lift up to 7.4t, a 460kg block can lift up to 22t, and so on.

This weight then gets deducted, along with any accessories, from the figures in the following load charts, to know what load weights can be lifted.

Now it’s time to get to the lifting.

Two styles of load charts are used for mobile cranes.

Here is the first:

This chart shows the natural arc the boom movement makes. The black curved lines indicate where each boom section extends to. This is where they get locked into place. Although the boom is 60m long, the hook can only operate up to 59.4m, because it hangs down, which shortens its distance to the ground.

Let’s look at the green markings for an example. We have 33.8m of boom out. Let’s say someone asks what we can lift at 28m radius. We follow the line up from 28 until we reach our 33.8m arc line. This shows the crane is good for 7.6t at 28m radius with 33.8m of boom out. It also shows that the crane can lift 7.6t up to 16m high from the ground.

Notice how as the hook goes higher on this arc, the crane can lift more weight. This principle is the same on every arc line. The further out on the radius, the lower the lifting capacity. As the boom angle increases the hook height, the higher the lifting capacity. 

But remember, when calculating what load weights can be lifted, the hook weight and lifting accessories weight need to be deducted from the gross capacity.

Here is the second chart:

This chart shows the same information as the previous. The boom length figures along the top match up, as well as the radius figures on either side.

To make life easy, let’s use the same example as the previous chart. We have 33.8m of boom out. Somebody asks us what we’re good for at 28 m radius. We follow from those two figures until meeting at 7.6t. If we had 30.1m of boom out in the same scenario, we would be able to lift 7.2t.

If you prefer to be talked through explanations, wath this presentation on mobile crane load charts.

Telehandler

Telehandlers, otherwise known as rough-terrain cranes, have the luxury of driving around on tyres to pick items up to carry elsewhere (Pick and Carry). The problem they have is tyres don’t give maximum stability when doing lifts. Which is why telehandlers have the option of using stabilisers to steady the machine. The stabilisers are commonly referred to as legs.

Telehandlers can lift with or without stabilisers down, but they’ll lift to their maximum potential with them down.

The following examples are of a Manitou MT1435. This machine can lift items three ways.

• With stabilisers down
• On tyres, with frame levelling
• On tyres, without frame levelling

On stabilisers

Here is an example of a telehandler load chart with the stabilisers down and using forks to lift.

The x-axis shows the radius (how far away the hook is to the machine), and the y-axis shows the hook height. The chart also shows the boom angle.

As you can see, the maximum lifting capacity is 3.5t. This weight can be lifted up to 4.65m out and 9m up. Once the hook gets to that point, if the operator wants to lift the load higher, they will have to stay within the 5m radius. The further out and higher the hook gets, the less weight the machine will lift.

On tyres with frame levelling

Lifting ‘on tyres’ means lifting without stabilisers. Frame levelling compensates for ground that isn’t level. The telehandler will try to level itself up so that it doesn’t lift while tilted.

Reading the load chart for this configuration is exactly the same as with using stabilisers. Except the telehandler will lift less weight.

Here’s an example.

This machine can only lift its maximum 3.5t up to roughly 2m radius and 5.2m high, which is quite a bit less than with stabilisers. If you follow the lines in the orange arch depiction of the boom, the lifting capacity reduces when the boom reaches the optimum points.

On tyres without frame levelling

There isn’t much difference in the telehandler’s lifting capacity between with or without frame levelling. Without it, the machine can lift its maximum 3.5t at 2.2m radius and approximately 4.75m high.

Conclusion

When first starting out, looking at these charts can be quite daunting. But they don’t need to be. If you are ever unsure, contact your superior or an Appointed Person.

Hopefully, this article will prevent you from having that problem.

---

Get your training here

Ready to take the next step in your lifting career? If you need training in any area of lifting operations, start building your experience today and consider enrolling in a course.

Similarly, if you’ve recently done a course and would like to progress to the next card level, book in with one of our assessors, so they can guide you through that qualification journey.

There is a shortage of skilled trades in the construction industry, so it needs operatives like you. This could be your opportunity to make a significant impact while advancing your career.

Click on images for more info

---