Load Indicator Technical Requirements: ISO 12484:2015
ISO 12484:2015, "Cranes — Load Indicators — Technical Requirements," is the dedicated standard for crane load indicators. It specifies the technical requirements, accuracy classes, test methods, and inspection rules for load indicators, including load sensors, load moment limiter displays, and audible and visual alarm devices.
Load Indicator Types and Functions
ISO 12484:2015 classifies load indicators into three categories: load indicators (devices that directly display the mass of the suspended load, comprising sensors and a display), load moment indicators (which show the load moment as a percentage of the rated capacity and serve as a core safety monitoring device), and combined indicators (multi-function displays that simultaneously show parameters such as Lifting Capacity, working radius, load moment percentage, and hook height). By sensor type, they are divided into pin-type sensors (measurement accuracy ±1%), tension/compression load cells (±1%), hydraulic sensors (±2%), and electronic load measuring devices (comprehensive accuracy ±3%).
The core functions of a load indicator include real-time display of the current suspended load (digital readout, accuracy ±5%), rated Lifting Capacity display (automatically referencing the corresponding Load Chart for the current operating conditions), overload alarm function (audible and visual warning at 90% of rated capacity, automatic stop at 100%), and self-diagnostic function (system and sensor checks at startup, with hoisting operations blocked in the event of a fault). The display refresh cycle is ≤0.5s, and the sensor signal update time is ≤0.1s.
Accuracy Requirements and Calibration
Load indicators are classified into three accuracy classes: Class A (combined error ≤±2%, for precision lifting operations), Class B (combined error ≤±5%, standard for general industrial cranes), and Class C (combined error ≤±10%, for manual or light-duty cranes). Accuracy is defined as the deviation between the indicated value and the actual value at any load point from 20% to 110% of the rated load, within the rated temperature range (-10°C to +50°C). Sensor zero-point temperature drift is ≤±0.1%/°C (Class A) or ≤±0.2%/°C (Class B), and creep is ≤±0.1% (30 min, at rated load).
Calibration requirements: a full system calibration must be performed after new installation or sensor replacement (using Standard Weights or force sensors at five points: 20%, 50%, 75%, 100%, and 110% of rated load), and calibration is required every 12 months during normal service. Calibration records must include the calibration date, personnel, instrument ID, and results, with a calibration label affixed to the display housing. Load indicator systems supplied by Kelude are calibrated to Class B accuracy before delivery and come with a calibration certificate.
| accuracy class | combined error | Application | Sensor Accuracy | calibration interval |
|---|---|---|---|---|
| AClass | ≤±2% | Precision Hoisting | ±1% | 6Months |
| BClass | ≤±5% | General Industrial | ±1%~±2% | 12Months |
| CClass | ≤±10% | Manual/Light Duty | ±3% | 24Months |
Display & Alarm System
The load indicator display must meet the following requirements: digital readout (LED or LCD panel with character height of at least 10 mm, clearly legible at a viewing distance of up to 2 m), backlit functionality (automatically activates in low-light conditions), and the ability to cycle or toggle between parameters such as Lifting Capacity, Working radius, Torque percentage, and Rated Lifting Capacity. The alarm system must provide Audible and Visual Alarm—a Buzzer rated at 85 dB or higher plus a flashing red Indicator light—with a pre-alarm triggered at 90% of rated capacity and a continuous Audible and Visual Alarm at 100% of rated capacity. The alarm signal must be audible over the ambient noise of the crane's operating environment (Buzzer volume must exceed background noise by at least 10 dB).
The display also features fault self-diagnosis: Sensor failure (Err01), system communication failure (Err02), and parameter configuration error (Err03), enabling maintenance personnel to quickly identify and resolve issues. The display's Protection Rating (IP) is IP54 or higher for Operator Cabin installations and IP65 or higher for outdoor control stations. Control buttons provide tactile feedback, and parameter settings are secured with password protection to prevent unauthorized changes. Kelude's load indicator system uses an industrial-grade LCD display that remains clearly readable in direct sunlight, with buttons tested to withstand 100,000 actuation cycles.
Testing & Inspection
Testing and Inspection are carried out in accordance with applicable standards and include: Type Test (accuracy verification, environmental test—high/low temperature, vibration, and salt spray—and electromagnetic compatibility testing, including radiated immunity of 30 V/m and electrostatic discharge of 8 kV/15 kV) and routine test (functional check, accuracy verification, and alarm verification). Periodic calibration is required every 12 months at the user's site. Re-calibration is mandatory after any Maintenance or Sensor replacement. Calibration records are maintained with the equipment. Kelude provides Installation & Commissioning, Calibration, and Maintenance services for its load indicator systems.
| Test Item | Method | acceptance criteria | Type |
|---|---|---|---|
| Accuracy | 20%~110%Loading5Point | ≤±5%(BClass) | type test+factory |
| Temperature | -10℃~+50℃Storage2h | Accuracy Drift≤±2% | Type Test |
| vibration | 5~200Hz/2g | No Functional Anomaly | Type Test |
| EMC | 30V/m/8kVStatic Electricity | No Malfunction | Type Test |
| guards | IP5X/IP6X | No Dust Ingress | Factory Acceptance Test |
Load Indicator FAQ: Accuracy, Calibration & Overload Settings
Q: What accuracy class should I choose for the load indicator?
A: Class A (≤±2%) is intended for precision hoisting applications, Class B (≤±5%) suits general-purpose industrial cranes, and Class C (≤±10%) is reserved for manual or light-duty equipment. Most industrial overhead and mobile cranes are specified with Class B accuracy. Kelude Heavy Industry supplies Class B load indicator systems as standard.
Q: How often does the load indicator need calibration?
A: A full system calibration is required after initial installation or whenever a force sensor is replaced. Under normal operating conditions, recalibration is recommended every 12 months. Calibration is performed using standard test weights or a calibrated force sensor at five load points: 20%, 50%, 75%, 100%, and 110% of rated load. The calibration label is affixed to the display housing.
Q: At what load level does the overload alarm activate?
A: An audible and visual pre-alarm (buzzer ≥85dB plus flashing red light) triggers at 90% of rated load. At 100% of rated load, a continuous audible and visual alarm sounds and hoisting and derricking movements are automatically stopped. The force sensor response time is ≤0.1s, and the display refresh rate is ≤0.5s.
Q: What ingress protection ratings apply to the display?
A: Displays installed in the operator cabin require a minimum rating of IP54, while those mounted on outdoor control stations require IP65. Character height must be at least 10mm for viewing distances up to 2m, with auto-backlit and sunlight-readable screens. Control keypads are rated IP67 with a service life of over 100,000 actuations. Kelude Heavy Industry displays use industrial-grade LCD panels.
