ISO 11662-1:2009 Mobile Crane Tipping Load Test Explained

Determining the Tipping Load

ISO 11662-1:2009 defines the tipping load as the load value at which the crane reaches the threshold of tipping. The standard specifies two methods for determining the tipping load: the theoretical calculation method, which derives the tipping load from the center-of-gravity positions of crane components and support reactions, and is suitable for predicting the tipping load during the design phase; and the experimental measurement method, which determines the tipping load directly through actual load testing and is used for verification after manufacturing. The theoretical calculation must account for the combined effects of dead weight, suspended load, counterweight, wind load, and inertia load, with a safety factor of ≥1.25.

The experimental measurement method requires the load to be applied at the hook center, with loading applied smoothly and slowly (loading speed not exceeding 5% of the rated load per second) until the outriggers or tires lift off the ground or the hoisting rope inclination angle reaches the specified value. During measurement, the outrigger reaction forces (measured using pressure sensors or load cells with an accuracy of ±1%), boom angle, working radius, and load values must be recorded at each load level. The tipping load is taken as the arithmetic mean of three valid tests, with the deviation of any individual result from the mean not exceeding ±5%.

Stability Test Procedures

The stability tests specified in the standard comprise static and dynamic stability tests. In the static stability test, the crane is positioned on level, firm ground (slope ≤0.5%) with outriggers fully extended (or tires in contact with the ground), and the boom is configured in the most unfavorable direction under rated conditions (the direction of maximum load moment). The load is then increased in stages to 125%–133% of the rated load and held for 5 minutes, during which the inclination angle and outrigger deformation are measured. In the dynamic stability test, combined motions such as hoisting, slewing, and luffing are performed under the rated load to assess the crane's dynamic stability, including the impact response during slewing start and braking, load swing during luffing, and load response during hoisting acceleration.

The acceptance criteria for the stability test are as follows: the maximum outrigger reaction force under any operating condition must not exceed 90% of the outrigger's rated capacity, and the difference between the reaction forces of any two outriggers must not exceed 30% of the average reaction force in the direction of the outrigger span. The overall inclination angle of the crane must not exceed 1°. During the test, the crane must show no abnormal noise, deformation, or leakage. The standard also specifies additional stability test requirements for mobile cranes configured in tower mode, where loading is applied in stages at the two extreme operating conditions: maximum working radius and maximum lifting capacity.

Measuring Instruments & Accuracy

The standard specifies the following requirements for test measuring instruments — electronic inclinometers or laser spirit levels for tilt angle measurement (accuracy ±0.1°), pressure sensors or load cells for outrigger reaction force measurement (accuracy ±1%), force sensors or dynamometers for load measurement (accuracy ±1%), and steel tape measures or laser distance sensors for working radius and lifting height measurement (accuracy ±1mm). All measuring instruments must be within their calibration validity period, with a calibration interval of ≤12 months.

Test environmental conditions — ambient temperature between -5°C and +40°C, wind speed ≤5 m/s (outdoor testing must be halted when wind speed exceeds 5 m/s), and a firm, level test ground with a load-bearing capacity of at least twice the crane's maximum outrigger reaction force and a ground inclination of ≤0.5%. Prior to testing, the crane undergoes a technical inspection to verify that all mechanisms function properly, the hydraulic system is leak-free, and safety devices are reliable and effective. Kelude completes stability tests on every mobile crane before delivery in accordance with ISO 11662-1:2009, ensuring safe and stable operation across all operating conditions.

Test Reports & Record Keeping

The test report must include — crane information (model, serial number, manufacturing date), test conditions (ambient temperature, wind speed, ground conditions), a list of test instruments (model, serial number, calibration validity), test records (outrigger reaction forces, tilt angles, and working radius measurements at each load level), and the test conclusion (whether stability is compliant and whether the design tipping load has been achieved). The report must be signed by the test supervisor and stamped with the testing organization's official seal.

The standard also specifies the retention period for test records — stability test reports must be kept for at least 3 years after the equipment is scrapped. If the crane undergoes a retrofit, overhaul, or a change in operating conditions, a new stability test must be performed. Kelude offers mobile crane stability testing services and issues nationally recognized test reports to its customers.

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