Overview
ISO 11662-1:1995 defines an experimental test method to determine the maximum capacity of a mobile crane to counterbalance loads applied to its hook block. The standard is intended for cranes whose rated capacity is based on static resistance to overturning (stability-based ratings), and it applies to all mobile cranes as defined in ISO 4306-2. It is used primarily for prototype verification and for adjusting a crane’s load chart where required.
Key topics and requirements
- Test principle: Suspend a known weight from the hook and either increase the load radius until the crane reaches the balance point (overturning moment equals resisting moment) or add incremental mass at a fixed radius until stability is lost.
- Balance condition: Defined as the condition where the overturning moment equals the maximum resisting moment of the crane.
- Measurements & accuracy:
- Load-radius measuring accuracy: ±1% or ±0.15 m, whichever is smaller.
- Test weight mass accuracy: ±1%.
- Means for measuring mass, radius and centre of gravity must be provided.
- Test setup and conditions:
- Supporting surface must be firm (concrete or equivalent).
- Crane level and gradient limits: ≤1%.
- For pneumatic-tyred cranes, tyre pressure within ±3% of manufacturer’s value; wheels ahead position.
- Fuel tank ≤ one-third full; fluids at operating levels.
- New machines should be operated about 4 hours before final adjustment and testing.
- Outriggers and mounts: Specific installation rules for tests “on outriggers” and crawler or tyre support conditions to ensure consistent stability measurement.
- Test procedure and reporting:
- Competent operator required.
- Mark axis of rotation projection and record radius and mass at balance point.
- Plot capacity curve (load in kg vs radius in m) using representative boom lengths.
- Test report must include machine identification, configurations, tyre/boom/engine data, counterweight, position of superstructure, test data and operator/date.
Applications and users
- Crane manufacturers (prototype validation and load chart verification)
- Testing laboratories and certification bodies (type-approval and compliance)
- Engineering and safety inspectors (on-site validation after modification)
- Fleet owners and rental companies (safety verification and documentation)
Practical benefits include verifying rated capacities, validating load charts, and ensuring safe operation limits for stability-based mobile cranes.
Related standards
Keywords: ISO 11662-1, mobile cranes, tipping loads, crane stability, load radius, balance point test, crane testing, load chart verification.
