The tonnage of a truck mounted crane is a core procurement parameter that requires comprehensive consideration of rated lifting capacity, operating radius, chassis load capacity, and operational requirements, while blindly choosing a model can easily lead to overloading, wasted transport capacity, or restrictions on registration.
This article, focusing on the procurement needs of engineering contractors and truck fleets, outlines the criteria for judging the tonnage of truck mounted cranes to facilitate accurate selection.
Rated Tonnage – What Does It Actually Mean?
The tonnage marked on the truck mounted crane refers to the maximum rated lifting capacity at the minimum radius.
- Key Point: The actual load bearing capacity decreases continuously with increasing lifting distance.
- Example: An 8 tons truck mounted crane can only lift 8 tons at close range; when the boom is fully extended and operating at a long distance, the actual load will be significantly reduced, and the load capacity cannot be estimated based on the nameplate tonnage.
How To Choose The Correct Tonnage?
1. Daily Lifting Weight Of Goods
Calculate the weight of the most frequently hoisted goods for the project and reserve a safety margin.
- For standard cargo weighing ≤3 tons: 3.2 tons or 4 tons truck mounted cranes are recommended.
- For standard cargo weighing 3–6 tons: 5 tons or 6.3 tons truck mounted cranes are recommended.
- For standard cargo weighing 6–10 tons: 8 tons or 10 tons truck mounted cranes are recommended.
- For standard cargo weighing >10 tons: Select a 12 tons or higher heavy duty truck mounted crane.
⚠️Safety Guidelines: For long term operation, the load should not exceed 75% of the equipment's rated capacity to avoid prolonged overloading and reduce the probability of hydraulic system failure.
2. Maximum Operating Radius
This is the most easily overlooked key factor.
- Close Range Hoisting (≤5m): the tonnage can be moderately smaller.
- Long Distance Hoisting (7–12m): requires upgrading to a larger tonnage crane.
If long distance outrigger lifting is frequently required, the crane model cannot be selected based on short distance load. Instead, the actual lifting capacity needs to be verified by referring to the crane load curve.
3. Truck Chassis Load Limits
The chassis's load bearing capacity determines the maximum tonnage of the crane it can handle; you can't simply choose the largest crane:
- Light Duty Chassis: Suitable for 3.2–6.3 ton cranes
- Medium Duty Chassis: Suitable for 6.3–10 ton cranes
- Heavy Duty Three Axle/four Axle Chassis: Suitable for 10–20 ton cranes
Excessively large crane tonnage can cause the vehicle's center of gravity to become unbalanced, posing significant safety hazards during driving and lifting. Furthermore, many countries' road regulations limit the total weight of the vehicle.
4. Working Site Conditions
- Urban Narrow Municipal Operations: Prioritize small to medium tonnage cranes with flexible vehicle bodies.
- Open Pit Mines, Large Construction Sites, Long Distance Hoisting: Medium to large tonnage truck mounted cranes.
- Mountain Roads, Muddy Unpaved Roads: Extreme full load operation is not recommended; allow for a tonnage margin.
5. Local Regulations And Road Requirements
Different countries have regulations regarding the load capacity and dimensions of freight vehicles and cranes. Oversized truck mounted cranes may face registration restrictions and road traffic limitations; therefore, it is essential to confirm the policies of the target market before purchasing.
Common Tonnage And Applicable Working Conditions
| Crane Tonnage | Applicable Scenarios | Advantages |
| 3.2t~4t | Municipal emergency repairs, seedling and landscaping, and small scale building material transportation | The vehicle is compact, agile, and fuel efficient, making it suitable for short distance urban operations |
| 5t~6.3t | Building material transportation, small construction sites, warehousing and loading/unloading | Most versatile, the mainstream choice for small and medium sized engineering vehicle fleets overseas |
| 8t~10t | Steel transfer, large equipment handling, water conservancy projects | Ample long distance lifting capacity, balancing load capacity and operating radius |
| 12t and above | Large scale infrastructure, mining materials, and heavy component hoisting | Heavy duty, long distance operations require a heavy duty multiaxle chassis |
Extra Tip: Straight Boom vs Knuckle Boom Crane
For the same nominal tonnage:
✅Straight Boom Truck Mounted Crane: For the same tonnage, it has a larger operating radius and is suitable for open outdoor areas.
✅Knuckle Boom Truck Mounted Crane: It occupies less space and is suitable for lifting inside containers and in confined spaces. However, its long distance lifting capacity is weaker than that of a straight boom crane.
Common Selection Mistakes
- Focusing solely on the nameplate tonnage without considering load reduction due to boom extension distance
- Indiscriminately pairing large chassis with small cranes is a waste of resources; forcibly installing large tonnage cranes on lightweight chassis poses safety risks
- Once no lifting margin is provided, prolonged near full load operation easily damages hydraulic cylinders and hoses
Frequently Asked Questions
Q: Are the lifting capacities of straight boom cranes and folding boom cranes the same for the same tonnage?
A: No, straight boom cranes perform better in long distance operations; folding boom cranes are preferred in confined spaces.
Q: How to accurately determine the lifting weight of a crane at a specified distance?
A: Refer to the load performance curve provided by the manufacturer.
Q: How should the tonnage be reserved for long distance lifting of heavy objects?
A: Select a model one level higher than the theoretically required tonnage.
Q: Can an 8 tons truck mounted crane be installed in a light truck?
A: It is not recommended, as the chassis load bearing capacity is insufficient, and there is a risk of tipping over.
Conclusion
Choosing the right tonnage for a truck mounted crane cannot be based solely on its maximum lifting capacity, it requires considering factors such as cargo weight, maximum lifting distance, chassis specifications, site conditions, and local regulations. For routine short distance operations, a suitable tonnage can be selected; for long distance, high frequency, heavy load operations, it is recommended to allow for a higher tonnage capacity. Proper selection can control procurement costs, ensure lifting operation safety, and extend the service life of the vehicle's hydraulic system.
