Kobelco cranes use a proprietary safety and control architecture built around the AML (Automatic Moment Limiter) system, which serves as the central platform for load management, boom angle monitoring, and overload protection. This system is standard across most modern Kobelco crawler and all-terrain crane models, and it works alongside a network of dedicated sensors to keep lifting operations within safe parameters. The sections below unpack how each component of that system functions, what sensors it relies on, and what options exist for upgrading or expanding it.
What control systems are built into Kobelco cranes?
Kobelco cranes are built around the AML (Automatic Moment Limiter) system as their primary control and safety platform. This proprietary system monitors load moment in real time, displays operational data to the operator, and automatically limits crane functions when a load approaches or exceeds the rated capacity for a given configuration. Most modern Kobelco crawler cranes also integrate electronic boom angle sensors, drum rotation encoders, and pressure transducers as part of the standard control package.
Beyond the AML, Kobelco incorporates several additional control layers depending on the model and configuration:
- Electronic load display units that show real-time load, radius, and boom angle in the operator cab
- Drum and winch control systems that regulate line speed and tension during lifting and lowering operations
- Slewing control systems that manage rotation speed and positioning
- Anti-two-block systems that cut power to the hoist when the hook block approaches the boom tip, preventing structural damage
Together, these systems form an integrated control environment where the AML acts as the brain, and the individual sensors and actuators act as the nervous system. The level of integration varies between older and newer Kobelco models, with more recent machines featuring CAN bus communication between components for faster data exchange and more reliable fault detection.
How does Kobelco’s AML system work?
The Kobelco AML (Automatic Moment Limiter) system works by continuously calculating the actual load moment and comparing it against the crane’s rated capacity for the current configuration. It takes inputs from boom angle sensors, load sensors, and boom length encoders, then uses the crane’s built-in capacity chart database to determine how close the crane is operating to its rated limit. When the load moment reaches a preset threshold, the AML restricts crane functions to prevent overload.
The AML display unit in the cab gives the operator a continuous readout of key parameters including:
- Actual load on the hook
- Working radius
- Boom angle and length
- Percentage of rated capacity currently in use
- Audible and visual warnings as the crane approaches its limit
When the crane reaches a critical threshold, typically around 90% of rated capacity, the AML triggers a warning. At 100% or above, it cuts out specific crane motions such as lowering, luffing out, or extending the boom, depending on which movement would increase the moment further. This automatic cutout is what distinguishes a moment limiter from a simple indicator: it does not just warn, it intervenes.
The AML system is also configuration-aware, meaning the operator must input the correct working configuration (boom length, jib angle, counterweight setup) before lifting. If the configuration entered does not match the actual rigging, the AML will calculate against the wrong capacity chart, which is why accurate setup is critical to safe operation.
What sensors does a Kobelco crane rely on for load monitoring?
A Kobelco crane relies on a combination of pressure transducers, angle sensors, and length encoders to monitor load in real time. The most direct load measurement comes from hydraulic pressure transducers fitted to the hoist circuit, which convert line pull into a calculated load value. Boom angle sensors and, on telescopic or luffing jib configurations, length encoders provide the geometric data needed to calculate the working radius and therefore the load moment.
The typical sensor suite on a Kobelco crane includes:
- Hydraulic pressure transducers on the hoist cylinders or winch circuits to measure line tension
- Boom angle sensors (typically inclinometers) mounted on the boom to track the luffing angle
- Boom length encoders on telescopic models to measure boom extension
- Anti-two-block sensors at the boom tip to detect hook block proximity
- Slewing angle sensors on certain models for configuration-dependent capacity management
It is worth noting that hydraulic pressure-based load measurement is an indirect method. The system calculates load from pressure readings rather than measuring force directly at the hook. This approach works reliably under normal conditions, but factors such as friction in the sheave system, dynamic loading during fast lifts, and sensor drift over time can introduce measurement inaccuracies. For high-precision applications or critical lifts, supplementary load measurement using dedicated load pins or load cells at the hook block provides a more direct and accurate reading.
Does Kobelco support third-party safety and control upgrades?
Kobelco cranes can support third-party safety and control upgrades, though compatibility depends on the model, age, and existing control architecture of the machine. Older Kobelco models with analogue or early digital AML systems are generally more straightforward to retrofit with external load monitoring equipment, anti-collision systems, or data logging devices, since these can be added as standalone systems alongside the OEM controls. Newer models with integrated CAN bus architectures may require more careful integration planning.
Third-party upgrades that are commonly applied to Kobelco cranes include:
- Supplementary load moment indicators or rated capacity indicators for redundancy or improved accuracy
- Anti-collision systems for multi-crane job sites or work near structures and power lines
- Remote data logging and cloud-based monitoring for fleet management and maintenance planning
- CCTV systems for blind lift monitoring and boom tip visibility
- Wireless load cells and load pins for direct force measurement at the hook or rigging point
When integrating third-party systems, the key consideration is whether the upgrade operates independently or interfaces with the OEM control system. Independent systems add a parallel layer of monitoring without modifying the existing AML, which is often the safest and most practical approach for retrofits. Systems that need to interface with or replace OEM components require careful engineering to ensure the crane’s original safety functions remain intact and certified.
What is the difference between a load moment indicator and a rated capacity indicator on a Kobelco crane?
On a Kobelco crane, a load moment indicator (LMI) measures and displays the relationship between the actual load moment and the crane’s maximum rated moment, expressed as a percentage. A rated capacity indicator (RCI) goes further by referencing the crane’s full rated capacity chart for the current configuration, displaying both the actual load and the maximum allowable load for that specific boom length, angle, and radius combination. The RCI is the more comprehensive system.
Load Moment Indicator (LMI)
An LMI calculates the product of the load and the working radius, then compares it to the crane’s maximum rated moment. It provides a percentage readout and triggers alarms when that percentage reaches a set threshold. LMIs are effective for general overload prevention, but they work from a single maximum moment value rather than a configuration-specific capacity chart. This makes them simpler but less precise for cranes that operate across a wide range of boom configurations.
Rated Capacity Indicator (RCI)
An RCI, sometimes referred to as a rated capacity limiter (RCL) when it also intervenes to stop crane motion, references the crane’s full load chart database. For any given combination of boom length, boom angle, and working radius, the RCI looks up the maximum permissible load from that chart and compares it to the actual measured load. This means the operator always sees the exact capacity available for the current configuration, not just a generic moment percentage. On Kobelco cranes, the AML system functions as an RCI, which is why it requires accurate configuration input from the operator before each lift.
Can Kobelco cranes be equipped with anti-collision systems?
Yes, Kobelco cranes can be equipped with anti-collision systems, either as factory-fitted options on certain models or as third-party retrofits. Anti-collision systems prevent cranes from entering defined exclusion zones or from colliding with other cranes operating in the same area. They are particularly relevant on congested job sites, offshore platforms, shipyards, and any environment where multiple cranes work in overlapping radii or near fixed structures such as buildings and power lines.
Anti-collision systems for cranes typically work using one or more of the following technologies:
- Zone limiting: Pre-programmed exclusion zones that restrict crane movement when the boom or load approaches a boundary
- Crane-to-crane communication: Radio-based systems that allow multiple cranes to share position data and trigger warnings or cutouts when their working envelopes overlap
- Proximity sensors: Ultrasonic or radar-based sensors mounted on the boom that detect nearby structures or objects
- GPS and angle-based calculation: Systems that calculate the three-dimensional position of the boom tip and compare it against a digital site map
For Kobelco cranes operating in environments where collision risk is a genuine concern, adding a dedicated anti-collision system provides a safety layer that the standard AML does not cover. The AML manages load moment, not spatial positioning, so the two systems address different risk categories and can operate in parallel without conflict.
When should a Kobelco crane control system be upgraded or replaced?
A Kobelco crane control system should be upgraded or replaced when it no longer meets current safety standards, when sensors or display units show signs of persistent inaccuracy or failure, or when the operational requirements of the crane have changed beyond the original system’s capability. Age alone is not always a sufficient reason, but a system that is difficult to calibrate, lacks spare parts availability, or cannot be maintained to specification is a genuine safety liability.
Specific situations that typically justify an upgrade or replacement include:
- The AML or sensor system produces inconsistent or unreliable readings that cannot be resolved through recalibration
- Spare parts for the existing control system are no longer available from the OEM or the aftermarket
- The crane is being reconfigured with a new boom system, jib, or counterweight arrangement that the original system cannot accommodate
- Regulatory requirements or client specifications demand a higher-specification safety system than the existing one provides
- The crane is moving into a new operating environment such as offshore or ATEX-classified areas where the existing system is not certified
- Data logging or remote monitoring capabilities are required for fleet management, and the existing system has no provision for them
A full replacement is not always necessary. In many cases, adding a parallel load monitoring system, replacing worn sensors, or retrofitting a data logging module can bring an older Kobelco crane’s control capability up to current requirements without touching the core AML architecture. The right approach depends on a technical assessment of the existing system’s condition and the specific performance gaps that need to be addressed.
How Pat-Kruger supports Kobelco crane control and safety
We design and supply advanced safety and control solutions that complement and extend the capabilities of Kobelco crane systems. Whether the requirement is a supplementary load monitoring system, a full AML replacement, or an entirely new layer of anti-collision and remote monitoring technology, we engineer solutions to fit the specific crane model, configuration, and operating environment.
Our services for Kobelco crane operators include:
- Load moment indicators and rated capacity indicators for retrofit or replacement of existing OEM systems
- Custom load pins and load cells for direct force measurement at the hook, rigging point, or sheave, providing more accurate load data than hydraulic pressure-based methods
- Anti-collision systems for multi-crane sites, offshore platforms, and work near exclusion zones
- ATEX-certified CCTV systems with pan-tilt-zoom capability for blind lift monitoring and boom tip visibility in hazardous areas
- Cloud-based data logging and remote monitoring for real-time load data access, historical records, and maintenance planning
- Winch force measurement and control systems for cranes with complex multi-drum or multi-line configurations
- Calibration services to verify and restore the accuracy of existing sensors and control systems
We work with crane owners, operators, and maintenance teams globally, providing both new installations and ongoing support for systems already in the field. If your Kobelco crane’s control system needs assessment, upgrading, or a fully tailored safety solution, contact our team to discuss the specific requirements of your machine and operation.
Frequently Asked Questions
How do I know if my Kobelco crane's AML system is reading accurately?
The most reliable way to verify AML accuracy is to perform a calibration check using a known test load and compare the displayed reading against a certified reference measurement, such as a calibrated load cell or load pin at the hook. If the AML reading deviates by more than the manufacturer's specified tolerance, recalibration is required. Regular calibration intervals should be part of your crane's planned maintenance schedule, and any persistent drift or inconsistency after recalibration is a strong indicator that a sensor component needs replacement.
What happens if the operator enters the wrong configuration into the AML before a lift?
If the wrong configuration is entered — for example, an incorrect boom length, jib angle, or counterweight setup — the AML will calculate load moment against the wrong capacity chart, which can either allow an unsafe lift to proceed or unnecessarily restrict a safe one. This is one of the most common sources of AML-related incidents on site, and it is entirely a human factors issue rather than a system fault. Establishing a pre-lift checklist that requires the operator to verify all configuration inputs against the physical rigging before each lift is the most effective way to prevent this error.
Can I add a wireless load cell to my Kobelco crane without interfering with the existing AML system?
Yes, a wireless load cell or load pin can typically be added as a standalone, parallel monitoring system that operates independently of the OEM AML. Because it does not interface with or modify the existing AML architecture, it does not affect the crane's original safety certification. The wireless load cell provides a direct force measurement at the hook or rigging point, which can be displayed on a separate indicator in the cab, giving the operator a more accurate secondary reference alongside the AML's hydraulic pressure-based reading.
How often should the sensors on a Kobelco crane be inspected or replaced?
Sensor inspection should be carried out as part of the crane's routine maintenance program, with the frequency determined by operating hours, environmental conditions, and the manufacturer's recommendations. Boom angle sensors and pressure transducers in particular are subject to mechanical wear, vibration fatigue, and environmental exposure that can cause drift or failure over time. Any sensor showing inconsistent output, physical damage, or calibration deviation beyond tolerance should be replaced promptly, as degraded sensor data directly compromises the accuracy of the AML's load moment calculations.
Is the Kobelco AML system compliant with international crane safety standards?
The Kobelco AML system is designed to meet the load moment limiting and rated capacity indicator requirements outlined in standards such as ISO 10245 and EN 13000, which govern crane safety systems in most international markets. However, compliance in a specific jurisdiction also depends on local regulations, the age of the machine, and how the system has been maintained and calibrated over time. If your crane is operating under a client specification or in a region with additional certification requirements — such as offshore environments governed by DNV or LOLER in the UK — it is worth having the system formally assessed against those specific requirements.
What are the most common mistakes crane operators make when using the AML system?
The three most frequent operator errors are entering incorrect configuration data before a lift, overriding or bypassing AML cutout functions without proper authorisation, and failing to account for dynamic loading during fast hoisting or slewing movements. Dynamic loads can temporarily spike well above the static load value, which the AML may not fully capture if the lift is performed too quickly. Training operators to treat AML inputs as a critical pre-lift step — not a formality — and to perform lifts smoothly within the system's response capability significantly reduces the risk of these errors.
At what point does it make more sense to replace the AML system entirely rather than repair it?
Replacement becomes the more practical option when the existing system can no longer be reliably calibrated, when spare parts are discontinued or unavailable, or when the cost of ongoing repairs approaches or exceeds the cost of a modern replacement system. It is also worth considering replacement when the crane's operational requirements have evolved — for example, if data logging, remote monitoring, or a higher-specification safety certification is now needed and the existing AML has no provision for those capabilities. A technical assessment of the system's current condition and performance gaps is the right starting point before committing to either path.