ISO 10245-2:2008 Crane Limiters and Indicators Explained
ISO 10245-2:2008, "Cranes — Limiting and indicating devices — Part 2: Mobile cranes," is the dedicated safety device standard for mobile cranes. It specifies the technical requirements, test methods, and inspection rules for safety devices including load moment limiters, lifting capacity limiters, and radius indicators.
Load Moment Limiter Requirements
ISO 10245-2:2008 sets out detailed technical requirements for the load moment limiter (LML) on mobile cranes. The LML must monitor the crane's load moment in real time (the product of lifting capacity and working radius). When the moment reaches 90% of the rated value, it must issue a pre-warning signal (both audible and visual alarms). At 100%, it must activate a limiting signal that automatically stops hoisting and radius-increasing movements, while still permitting lowering and radius-decreasing operations. The LML system accuracy must be no worse than ±5% (combined error, including sensor and calculation errors), with accuracy drift not exceeding ±2% across the full operating temperature range of -20°C to +60°C.
The LML must feature a self-check function — performing automatic sensor zero-point calibration and system self-diagnostics at every power-on. If self-check fails, hoisting operations must be inhibited and a fault code displayed. The LML must record at least the last 100 overload events (overload time, overload value, and action taken), with data storage unaffected by power loss (EEPROM or Flash memory). The LML operation panel must display core parameters including current lifting capacity, working radius, moment percentage, and rated lifting capacity, with a display refresh cycle of ≤0.5s.
Lifting Capacity Limiter and Radius Indicator
The lifting capacity limiter (load limiter) must be provided independently of the LML, serving as a backup protection device in the event of load moment limiter failure. It must automatically stop hoisting action when the lifting capacity exceeds 105% of the rated value. The load cell is installed at the fixed end of the hoisting rope or at the drum support, with a protection rating of at least IP65. The radius indicator must display the current working radius in real time (horizontal distance from the hook center to the slewing center) with an accuracy of ±2% or ±0.1m, whichever is greater. For telescopic boom cranes, the radius indicator must be calibrated in segments for different boom length combinations.
Additionally, the standard requires the height limit switch to issue a pre-warning 0.5m before the hook reaches its highest position and to automatically stop hoisting at the limit position. A slewing angle indicator is required for tower-type operating conditions or when angular position limiting is fitted. All limiters and indicators must be vibration-resistant, waterproof, and dustproof (protection rating ≥IP54), with a reliability target of MTBF ≥5000h over the crane's life cycle (design working life ≥10 years).
| safety device | Function | Setpoint | Sensor Type | Accuracy |
|---|---|---|---|---|
| Load moment limiter (LML) | Real-time Torque Monitoring | 100%Rated load moment Stop | force sensor+Angle | ±5% |
| Lifting Capacity Limiter / Load Limiter | overload Backup Protection | 105%rated load Stop | pin Sensor | ±3% |
| Radius indicator | Real-time Working radius Display | — | angle sensor | ±2% |
| Height Limit Switch | Hoisting Height Limiter | Distance to Limit0.5mearly warning | Limit switch | — |
| Anglelimiter | Boom angle Limit | Setting Angle±2° | Angle Encoder | ±1° |
Test Methods & Inspection Rules
The standard specifies both type tests and routine tests. Type tests are conducted during product qualification and cover accuracy verification (at least 3 repeated measurements at 20%, 50%, 75%, 100%, and 110% of rated load to calculate combined error), environmental adaptability tests (storage and operation at -20°C to +60°C, vibration testing from 5 to 200 Hz at 2g, and salt spray testing for a minimum of 48 hours), and electromagnetic compatibility testing (radiated immunity at 30 V/m, electrostatic discharge at 8 kV contact / 15 kV air). Routine tests are performed unit by unit and include functional checks (self-check function, early warning and limit functions, display function), accuracy verification at 50% and 100% of rated load, and alarm function testing.
The standard also requires an annual periodic calibration of the LML system using standard test weights or force sensors to verify system accuracy, with calibration records archived with the equipment. A full system recalibration is required after any sensor repair or replacement. The LML Safety Monitoring System supplied by Kelude for mobile cranes holds CE Certification and meets the stringent accuracy and reliability requirements of ISO 10245-2:2008.
Fault Diagnosis & Maintenance
The standard also defines requirements for fault diagnosis and maintenance of the LML system. Common faults include abnormal sensor signals, system accuracy drift, alarm function failure, and display anomalies. On-site troubleshooting can be performed using the panel self-check function to quickly isolate the fault area — sensor faults are identified by checking sensor voltage, system accuracy is verified through load testing, and alarm functions are tested with simulated signals. After fault elimination, accuracy verification must be repeated and maintenance records updated.
Routine maintenance requirements include checking the LML panel display, sensor cable integrity, and alarm function (a single audible beep during power-on self-test) at the start of each shift. Monthly accuracy verification using standard test weights (or force sensors) with recorded results is also required, along with an annual full system calibration performed by qualified personnel. Software updates for the LML system must be authorized by the manufacturer — users are not permitted to modify system parameters on their own.
| maintenance item | Period | Content | acceptance criteria |
|---|---|---|---|
| Display Check | Per Shift | Panel Display Normal | Readings Clear |
| Alarm Testing | Per Shift | Self-test Buzzer | Audible/Visual Normal |
| accuracy verification | Monthly | 50%/100%Load | ±5%Internal |
| Complete Machine Calibration | Annually | Full Measuring Range Calibration | combined error Compliant |
| Sensor Display Check | Quarterly | Connection Cable/Plug | No Loose Connection/Corrosion |
Frequently Asked Questions
Q: What is the difference between a load moment limiter and a lifting capacity limiter?
A: The load moment limiter (LML) provides real-time monitoring of the load moment (lifting capacity × working radius) and stops hoisting and radius increase when 100% of the rated load moment is reached. The lifting capacity limiter acts as a backup safety device, independent of the LML, and stops hoisting when the load exceeds 105% of the rated capacity. The two systems complement each other to ensure safe operation.
Q: What are the accuracy requirements for the LML system?
A: The combined error is ≤±5% (including sensor and calculation errors), with accuracy drift of ≤±2% over the operating temperature range of -20°C to +60°C. Sensor load response time is ≤0.1s. Calibration is required at least once a year; sensors must be adjusted or replaced if accuracy exceeds the specified limits.
Q: Which safety devices are mandatory on mobile cranes?
A: The following are mandatory requirements: load moment limiter, lifting capacity limiter, radius indicator, and height limit switch. Tower crane configurations must also include a slewing angle indicator. All safety devices must have a protection rating of at least IP54. Kelude mobile cranes come standard with a full safety monitoring system.
Q: What is the calibration interval and procedure for the LML system?
A: Accuracy is verified monthly using standard test loads at 50% and 100% of the rated lifting capacity. A full-range calibration of the entire system is performed annually by qualified personnel. Re-calibration is required after any maintenance or sensor replacement. All calibration records are kept on file for reference.
