“How much can a knuckle boom crane lift?” has two answers. The rating on the brochure, from 1.6 t to 50 t across our own range, is its lifting capacity with the boom folded in close to the column, the most it can ever lift. The figure that decides your job is what it lifts at the reach you need, and that is usually a fraction of the rating.
This guide gives both answers with real numbers. Every figure for our cranes comes from the technical drawings and load charts of seven BOB-LIFT knuckle boom truck mounted cranes, from 2 t to 50 t, compiled in October 2026. You will see how capacity falls with reach, what the t·m rating means, how big knuckle boom cranes get, and how to size one for your heaviest lift.
Key takeaways
- A knuckle boom crane’s rated capacity applies only close to the column, about 2 m out on our 2 t to 12 t models.
- At full reach, our cranes lift about 6% to 22% of their rating: our 10 t crane lifts 1,150 kg at 14.68 m.
- Neither the tonnage nor the t·m rating tells you what a crane lifts at your reach. Our 12 t crane out-lifts our 10 t at around 8 m but lifts less from about 12 m out to full reach.
- Our largest knuckle boom crane, the SQZ1000, is rated at 50,000 kg and 90 t·m, and lifts 3,230 kg at 20.3 m.
- To size a crane, find your heaviest load at your longest reach and check it on the load chart, with margin.
How much can a knuckle boom crane lift?
A knuckle boom crane lifts its full rated capacity only about 2 m from the column. Our truck-mounted knuckle boom cranes are rated from 1.6 t to 50 t, but at full reach the seven models below lift roughly 6% to 22% of their rating. Our 10 t crane, for example, lifts 10,000 kg at 2.0 m, 4,650 kg at 4.5 m and 1,150 kg at 14.68 m. The load falls as the boom extends because the same lifting moment is spread over a longer lever.
Knuckle boom crane lifting capacity by model
The table shows what that means for seven of our knuckle boom truck mounted cranes. Each figure comes from the model’s technical drawing and load chart.
| Model | Rated capacity | Lifting moment | Load at 4 to 5 m | Load at full reach | Crane weight |
|---|---|---|---|---|---|
| SQ2ZA4 (2 t) | 2,000 kg at 2.1 m | 4.2 t·m | 1,000 kg at 4.1 m | 300 kg at 7.54 m | 750 kg |
| SQ5ZA3 (5 t) | 5,000 kg at 2.1 m | 10.5 t·m | 2,350 kg at 4.45 m | 1,100 kg at 8.05 m | 2,286 kg |
| SQ10ZA6 (10 t) | 10,000 kg at 2.0 m | 21 t·m | 4,650 kg at 4.5 m | 1,150 kg at 14.68 m | 3,700 kg |
| SQ12ZA6 (12 t) | 12,000 kg at 2.25 m | 27 t·m | 5,450 kg at 4.7 m | 1,000 kg at 14.5 m | 4,800 kg |
| SQZ430 (20 t) | 20,000 kg (minimum reach) | 42.3 t·m | 8,700 kg at 4.4 m | 1,910 kg at 16.6 m | 5,500 kg |
| SQZ560 (28 t) | 28,000 kg (minimum reach) | 57.3 t·m | 12,300 kg at 4.2 m | 3,050 kg at 15.9 m | 6,100 kg |
| SQZ1000 (50 t) | 50,000 kg (minimum reach) | 90 t·m | 16,700 kg at 4.6 m | 3,230 kg at 20.3 m | 10,000 kg |
Read across any row and the pattern is the same. Our 28 t SQZ560 lifts 28,000 kg at minimum reach, 12,300 kg at 4.2 m and 3,050 kg at its full 15.9 m, about 11% of its rating. At full reach, every crane in the table lifts between about 6% and 22% of its rating.
Knuckle boom crane load chart: why capacity falls with reach
A crane’s structure and hydraulics can resist only a certain turning force, its lifting moment. The lifting moment is the load multiplied by its distance from the slewing centre, written in tonne-metres (t·m). This is the crane’s tonne-metre rating. Move the same load twice as far out and it puts twice the moment on the crane.
That is why the rating and the moment go together. Divide the moment by the rating and you get roughly the reach where the full rating applies: 27 t·m ÷ 12 t is 2.25 m for our 12 t crane, exactly where its chart lists 12,000 kg. Further out, the load chart takes over. The chart is not a straight division at every point, because the boom’s own weight also acts on the crane as it extends, so always read the real chart rather than calculating.
For a full walkthrough of the boom angles, sections and lines on a chart, read our guide on how to read a crane load chart.
Can a bigger crane lift less? Why the rating alone misleads
The tonnage in a crane’s name is its rating at minimum reach. The t·m rating describes the crane’s strength, but a longer, heavier boom uses part of that strength to hold itself up. So neither figure tells you what the crane lifts at your reach.
Two of our cranes show it. The SQ12ZA6 is rated at 12 t and 27 t·m; the SQ10ZA6 at 10 t and 21 t·m. Close in and to around 8 m, the 12 t crane lifts more: 2,500 kg at 8.19 m, while the 10 t crane lifts 2,280 kg slightly further out at 8.51 m. Around 10 m the two are close: 1,850 kg at 10.1 m for the 12 t, 1,800 kg at 10.56 m for the 10 t.
Beyond that the order flips. At 12.2 m the 12 t lifts 1,400 kg, while the 10 t lifts more, 1,480 kg, even further out at 12.63 m. At full reach it is 1,000 kg at 14.5 m for the 12 t against 1,150 kg at 14.68 m for the 10 t. The 12 t crane also weighs 4,800 kg against 3,700 kg, which uses more of your truck’s payload. If your hardest lift is at the end of the boom, the smaller crane is the stronger choice. Compare load charts at your working reach, not ratings.
How big do knuckle boom cranes get?
Our largest knuckle boom truck mounted crane is the SQZ1000. Its drawing gives a 50,000 kg maximum lifting capacity, a 90 t·m lifting moment, a 10,000 kg self weight and a 20.3 m maximum reach. Its load chart shows 25,500 kg at 3 m, 7,300 kg at 10 m and 3,230 kg at 20.3 m.
A crane that size needs a heavy truck. It weighs 10 t before the truck, the body and the load are added, and its outriggers must take the full lifting moment into firm ground. For most work, a smaller crane with the right chart at your reach is the better buy. Our truck mounted crane installation guide covers how crane size and chassis go together.
For the 25 t class in detail, with its load chart from 4.2 m to 15.9 m and the truck it needs, read our 25 ton knuckle boom crane guide.
What else reduces a knuckle boom crane’s capacity?
The load chart is the maximum under the conditions it was drawn for. Several things reduce what you can safely lift:
- Everything below the hook counts. Slings, shackles, a hook block, a grab, a basket or a fly jib are part of the load, so subtract their weight from the chart figure.
- Outriggers and ground. Charts assume the outriggers are set as the manual requires on firm, level ground. Soft ground or a short outrigger setting reduces stability.
- Boom configuration. Large knuckle booms have different chart lines depending on how many extension sections are out. Use the line that matches the boom you are using.
- Wind and dynamic loads. Wind on a large load, and sudden starts or stops, add force the chart does not include.
- Side pull and dragging. A crane is rated for vertical lifts. Dragging a load or pulling it sideways puts loads on the boom that the chart does not allow for.
Knuckle boom or telescopic boom: which lifts more?
Neither boom type lifts more as a rule; compare the two cranes’ load charts at your working reach. At the same tonnage, the bigger differences between the two boom types are in reach and in how they work: a knuckle boom folds compactly behind the cab and can reach over obstacles, while a telescopic boom gives a straight, long reach. We compared five pairs of our own cranes at the same tonnage in knuckle boom vs telescopic boom truck crane.
How to size a knuckle boom crane for your job
- List your lifts. For each, note the load, including everything below the hook, and the furthest reach from where the crane will stand.
- Find the hardest lift. It is not always the heaviest load. A light load at long reach can need a bigger crane than a heavy load close in.
- Check the load chart. Pick a crane whose chart covers the hardest lift at that reach, with a margin for the conditions above.
- Check the truck. Make sure the chassis can carry the crane’s weight and its outriggers can be set where you work.
- Ask for the chart. A supplier should send the real load chart for the model they quote, not only the rating.
Frequently asked questions
How much can a 10 ton knuckle boom crane lift?
It lifts 10 t only close to the column. Our SQ10ZA6 lifts 10,000 kg at 2.0 m, 4,650 kg at 4.5 m, 2,280 kg at 8.51 m and 1,150 kg at its full 14.68 m reach.
What is the biggest knuckle boom crane?
Our largest is the SQZ1000, rated at 50,000 kg and 90 t·m with a 20.3 m reach. Larger knuckle boom cranes exist for ships and heavy industry, but for truck mounting the chassis usually limits size first.
What does t·m mean on a crane?
Tonne-metres: the load multiplied by its distance from the slewing centre. Our 12 t crane is rated at 27 t·m, so it holds 12 t at 2.25 m (27 ÷ 12), but far less at longer reach once the boom’s own weight is counted.
How much can a boom truck lift?
It depends on the crane mounted on it. Our knuckle boom truck cranes are rated from 1.6 t to 50 t, but each lifts its rating only at minimum reach. Check the load chart at your working reach.
Can a knuckle boom crane lift more than its load chart?
No. The load chart is the limit, and it already assumes the outriggers are set correctly on firm, level ground. Lifting beyond it risks tipping the truck or damaging the boom and hydraulics.
Where do I find a knuckle boom crane load chart?
The load chart is part of each model’s technical drawing and operator’s manual. It lists the safe load at each reach. Ask your supplier for the chart of the exact model and boom configuration they quote, not only the rated tonnage.
Get the chart for your lift
The rating sells a crane; the load chart tells you whether it does your job. Send us your heaviest load, the reach you need and your truck, and we will suggest models from our knuckle boom truck mounted cranes with the load chart for each. Contact us to start.
