Contents
Overview
What is a crane load chart and how do you read it?
A crane load chart, also called a duty chart, is the maker’s table of how much one crane can lift at each radius and boom length in a stated set-up. To read it, find the row for your radius and the column for your boom length, and check the figure there is at least the total weight on the hook.
Each chart is drawn up for a single crane model, and it holds only with the counterweight, outrigger spread, jib and slewing range it states. The slewing range is the arc the crane may turn through while it carries the load. Change any of those and another chart applies, with its own figures.
In short
- In Great Britain, LOLER requires a crane whose safe working load changes with its set-up to be marked with the load for each set-up, or to have that information kept with it.
- Capacity falls as the load moves further out from the crane, and a longer boom at the same radius usually lifts less.
- Only the maker’s chart for the crane on site, in the set-up it is rigged in, can be used to plan a real lift.
Our crane hire and contract lifting service offers two routes: you hire a crane through us and plan the lift yourself, or we plan and run the whole lift for you as a contract lift. On a contract lift, our own appointed person plans the lift and writes the lift plan. The appointed person is the role BS 7121-1 puts in charge of planning a crane lift.
Sources
Where load chart guidance comes from
In Great Britain, regulation 7 of LOLER requires lifting machinery whose safe working load depends on its configuration to be clearly marked with the safe working load for each configuration, or to have information showing it kept with the machinery. HSE’s L113, the approved code of practice and guidance on LOLER, applies this to machinery whose safe working load varies with its operating radius or its configuration, and gives a chart as one way to provide the information. Our guide to HSE L113 explains how its code of practice and its guidance differ in status. Northern Ireland has the same requirement in regulation 7 of the Lifting Operations and Lifting Equipment Regulations (Northern Ireland) 1999.
Under BS EN 13000, the European product standard for mobile cranes, the crane’s manual gives a load chart for every configuration the maker permits. The charts themselves are each maker’s own, so the set-ups they cover and the notes printed with them differ from one maker and model to the next. Liebherr’s data sheet for its LR 1130.1 crawler crane, for example, says its printed charts are for reference only and that the duty for a real lift comes from the chart in the operator’s cab or the manual. Our crane library shows how each crane has its own charts: the Liebherr LTM 1060-3.1 and the Grove GMK3060 are both 60 t all-terrain cranes, and each one’s page offers its maker’s specification sheet, load charts included.
Where this guide quotes a maker, the figure or note is an example from that maker’s published data sheet, named beside it. Use the load chart and instructions for the crane on site, from its maker, and have the lift planned by a competent person.
Layout
How to read the rows and columns of a load chart
Liebherr’s LR 1130.1 sheet sets its charts out as a grid: radius runs down the side in metres, boom length runs across the top, and each cell gives the capacity in tonnes for that pair.
Radius
The radius is the horizontal distance from the centre of the crane’s slew ring, the large bearing the crane’s upper works turn on, to the load’s centre of gravity, taken at the furthest point the load reaches, as our guide What size crane do I need? sets out. Liebherr states that the radii on its LR 1130.1 charts are measured from the centre of the slew ring with the load on the hook. Capacity drops quickly as the radius grows, so a load well inside the chart at 10 m can be beyond it at 25 m.
Boom length
Boom length is how far the main boom is extended for the lift. A longer boom reaches higher and further out, but at the same radius it usually carries less than a shorter one. Near the edge of a short boom’s reach, a longer boom can be the one that lifts more, as the 20 m row of the example chart below shows. A jib, an extra section fitted to the end of the main boom for more height or reach, has its own tables: Liebherr’s LTM 1060-3.1 data sheet gives separate ones for its swing-away jibs.
The figure in the cell
The number where the row and column meet is the crane’s rated capacity for that radius and boom length in that set-up: the heaviest total load it can take there. Our guide to the difference between SWL and WLL explains how rated capacity relates to the other load ratings.
If your radius or boom length falls between two printed values, do not estimate a figure between them. Ask the appointed person, who works from the maker’s chart and its notes.
Set-up
How the crane’s set-up changes the chart
One crane can carry many charts, each tied to a particular rigging. Liebherr’s data sheet for the LTM 1060-3.1, a 60 t all-terrain crane, gives separate tables for several counterweight combinations, and for working through a full 360 degrees or over the rear only. Counterweight is the set of removable weights at the back of the crane that balance the load.
Outriggers are the extending legs a mobile crane lowers onto the ground to lift from. BS 7121-3, the code of practice for mobile cranes, says outriggers should be set as the maker’s instructions and the duty chart say. Some cranes can lift with their outriggers part extended, and BS 7121-3 says the appointed person should plan and control that. Where a crane’s charts allow a part-extended spread, it works from the chart for that spread.
The charts also assume firm, level ground: Liebherr gives the LR 1130.1 capacities for the crane standing on firm, horizontal ground. Whether the ground can carry the outrigger loads is a separate check, which our guide What Size Outrigger Mats Do I Need? covers.
On a mobile crane built to BS EN 13000, the rated capacity limiter, the device in the cab that stops the crane being moved into an overload, is set to the configuration in use, and the operator can check that setting against the load chart. Our guide to BS EN 13000 covers the limiter and the warnings it gives.
Deductions
Deductions for the hook block and lifting gear
The capacity on a load chart has to cover more than the load itself. In Great Britain, HSE’s guidance in L113 says that in some cases, such as with a mobile crane, the hook block and other lifting accessories should be counted as part of the load being lifted. Liebherr’s LR 1130.1 data sheet puts it the other way round: the weight of the lifting device, hoist ropes included, has to be deducted from the capacity shown.
Either way the sum comes out the same. Add up:
- the load, with its weight from the maker’s data or a weighbridge ticket;
- the hook block, the block and hook on the end of the hoist rope;
- the slings and shackles that attach the load, covered in our guides to lifting slings and shackles;
- any spreader beam or lifting beam between the hook and the load;
- the hoist rope, and anything else the chart’s notes say to deduct, such as equipment carried on the boom.
The total must stay within the capacity the chart gives for the radius and boom length of the lift, in the set-up the crane will use. Each maker prints its own notes with its charts, so read the ones printed with the chart you are working from.
Working range
The working range diagram: height and reach
Alongside the capacity tables, a maker’s data sheet has a working range diagram. In Liebherr’s LR 1130.1 sheet it plots hook height against radius, with a curve for each boom length and lines marking the boom angle.
Use it to check height. If the load has to pass over a roof edge or a building, the diagram shows which boom lengths still give enough height at the radius needed. The boom length chosen then sets the column you read on the load chart, and our guide What size crane do I need? explains how height feeds into choosing the crane.
Example
A worked example (a made-up crane and lift)
This example uses an invented load chart and an invented job. Every figure is a round number for illustration, and none comes from a real crane or is based on any crane named on this page.
The made-up chart below is for the crane’s main boom with full counterweight and the outriggers fully extended, working through 360 degrees. Capacities are in tonnes, and a dash means the boom cannot work at that radius.
| Radius | 20 m boom | 30 m boom | 40 m boom |
|---|---|---|---|
| 5 m | 30.0 | 24.0 | – |
| 10 m | 14.0 | 12.5 | 11.0 |
| 15 m | 8.5 | 8.0 | 7.0 |
| 20 m | – | 6.0 | 5.0 |
| 25 m | – | 3.5 | 3.0 |
| 30 m | – | – | 2.0 |
The made-up job is to lift a machine over the edge of a building and land it 20 m from the centre of the crane’s slew ring.
- Total load. The machine weighs 3.5 t, from its maker’s data. The slings and shackles add 0.2 t and the hook block 0.3 t, giving 4.0 t on the hook.
- Radius. The landing point is the furthest the load goes, so the radius is 20 m.
- Boom length. The crane’s working range diagram, also made up, shows a 30 m boom gives enough height to clear the building edge at 20 m.
- Read the chart. The 20 m row and the 30 m column meet at 6.0 t. The 4.0 t total is within it, so on paper this set-up can make the lift.
If the crane could only set up 5 m further back, the radius would grow to 25 m and the chart would give 3.5 t, less than the 4.0 t total. This set-up would then not make the lift, and the appointed person would look again at where the crane stands or which crane is used, as What size crane do I need? explains. Fitting the 40 m boom at 20 m would also lower the figure, from 6.0 t to 5.0 t.
A real lift works from the chart supplied for the actual crane, and the appointed person checks it against the rest of the lift plan, from the ground to the wind limit.
From our lifts
We check the chart is for the exact crane and the set-up it will have on the day: counterweight, outrigger spread, any jib and the slewing range. Then we add the hook block and all the lifting gear to the load’s weight, and read the figure at the furthest radius the load goes, with a boom long enough to clear everything.
The crane can’t set up where the plan put it. A parked lorry or a soft patch of ground pushes it a few metres back, and the radius grows with it. A few metres can take a big bite out of the capacity. When that happens the lift stops and the appointed person checks the chart again for the new position.
Never read between two lines on the chart. If your radius falls between two rows, work to the larger radius, and if your boom length falls between two columns, work to the longer boom. Both give the lower figure. And measure the radius all the way to where the load lands.
Questions
Common questions
What is the purpose of a crane load chart?
It gives the rated capacity of one crane across its reach, set-up by set-up, so the people planning and running a lift can check the total load against it. In Great Britain, regulation 7 of LOLER requires that information for lifting machinery whose rating depends on how it is configured, marked on the machine or kept with it.
What is crane radius?
Crane radius is the horizontal distance from the centre of the crane’s slew ring to the centre of gravity of the load. It is measured at the furthest point the load reaches between pick-up and landing. The further out the radius, the less the crane can lift.
Is a duty chart the same as a load chart?
Yes. Duty chart is the term BS 7121-3 uses, and Liebherr’s data sheets call the same tables load charts. Both mean the capacity tables for one crane model, and each applies only to the configuration printed with it, together with its notes on what has to be deducted.
How do you check a crane can lift a load?
Add the hook block and all the lifting gear to the weight of the load to get the total. Measure the radius to the load’s furthest position and find the boom length that gives enough height. The capacity on the chart for that radius and boom length, in the set-up the crane will use, must be at least that total.
Does the hook block count as part of the load?
Yes. Add the hook block to the load with the rest of the lifting gear. In Great Britain, HSE’s L113 guidance gives a mobile crane as a case where lifting accessories should be counted as part of the load. Liebherr’s LR 1130.1 data sheet instead deducts them from the capacity shown, with the same result.
What is the safe load indicator on a crane?
It is the rated capacity indicator, which warns the operator, by sight and sound, as the load nears the crane’s capacity for its set-up. On a mobile crane built to BS EN 13000, a rated capacity limiter then allows only movements that reduce the load. Both work from the configuration set in the cab.
Can you use the load chart from a similar crane?
No. Charts differ from one model to the next, and between the configurations of a single crane, so two cranes that look alike can have different figures. A lift is planned from the maker’s chart for the crane that will actually be on site, set up the way it will be on the day.
Who reads the load chart when a lift is planned?
The appointed person reads it when planning the lift, and the crane operator works to it. In Great Britain, regulation 8 of LOLER requires every lifting operation to be planned by a competent person. BS 7121-1 gives that job on a crane lift to the appointed person. Our guide Appointed Person and Other Lifting Roles covers each role.
Get help
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Call us on 0800 008 6096 or email office@synergy-lifting.co.uk. Send us the weight of the load and where that figure comes from, with photos or a site plan showing where the crane could stand and where the load has to land, and we will recommend a crane and quote for the lift.
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