Temporary works & site · Cranes & lifting
Crawler crane lift check (radius, capacity, ground bearing) calculator
Checks a crawler-crane lift against a load chart (radius vs rated capacity, interpolated), adds hook block and rigging, computes the boom angle and tip height from the boom length and radius, the clearance to an obstruction, and the track bearing pressure with the load over the end of the tracks. Draws the crane elevation to scale.
Standard: AS 2550.1 / AS 2550.5 mobile & crawler cranes · lift-planning practice: > 75 % of rated capacity = critical lift
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Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Load chart: radius (m), rated capacity (t) — one per line | 6, 80 8, 60 10, 46 12, 37 14, 30 16, 25 20, 18 24, 13.5 28, 10.5 32, 8.2 | |
| Boom length | 36 | m |
| Working radius | 14 | m |
| Load | 18 | t |
| Hook block + rigging | 1.6 | t |
| Crane mass incl. counterweight | 95 | t |
| Track length on ground | 6.2 | m |
| Track shoe width | 0.9 | m |
| Track centres | 4.6 | m |
| Allowable bearing (platform + crane mats) | 300 | kPa |
| Obstruction height | 12 | m |
| Obstruction distance from slew centre | 9 | m |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Rated capacity at radius | 30.00 | t |
| Load incl. hook & rigging | 19.60 | t |
| Utilisation of chart | 65.3 | % |
| Boom angle | 69.7 | ° |
| Boom tip height | 36.0 | m |
| Boom clearance over obstruction | 10.46 | m |
| Peak track bearing pressure | 282 | kPa |
- ✓ Load ≤ rated capacity — 65.3 %
- ✓ Utilisation ≤ 75 % (else plan as a critical lift) — 65.3 %
- ✓ Boom clears obstruction by ≥ 1 m — 10.46 m
- ✓ Track bearing ≤ allowable — 282 kPa vs 300
Method, formulas and assumptions
- Capacity interpolated linearly in the load chart; the rated capacity must include all lifted items (hook block, slings, spreader). Lifts above 75 % of rated capacity are normally treated as critical lifts needing an engineered plan.
- Track pressure: crane + load acting over two tracks, with the load moment about the track centre giving a trapezoidal distribution along the track (e/L ≤ 1/6 for full contact). Use the manufacturer's ground-pressure data for design.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.