Franna was the brainchild of innovator Dave Francis, who saw a need to improve the safety of pick and carry “Tractor” cranes of the day … remember their nickname “Wobblies”? Over the decades, advancements in safety systems have significantly enhanced the reliability, performance, and operational ease of cranes. The history of safety system development for pick-and-carry cranes, as outlined by Franna’s journey, exemplifies the industry’s commitment to reducing risks and improving outcomes.
A timeline of progress: From radius charts to dynamic systems
The evolution of crane safety systems spans over four decades, driven by advancements in technology and a deeper understanding of operational challenges.
1978: Radius Load Charts
Early safety measures relied on radius charts that provided crane capacity data for straight-ahead configurations only. Operators were advised to “derate accordingly” on side slopes, no detailed guidance was offered, leaving room for human error.
The earliest safety mechanisms, such as the basic overload light, were rudimentary. These systems provided simple alerts when the rear axle was getting “light” but lacked the intelligence or precision required to guide operators effectively.
1992: Articulated Load Charts
By the early 1990s, articulated charts were introduced, incorporating capacity reductions when articulation exceeded 10 degrees. Load Charts tables had individual capacities for length and angle which gave the operator the ability to read the rated capacity significantly more accurately than the primitive Radius Load Chart.
It also incorporated reduced rated capacities when articulating. The system displayed a Yellow LED when articulated more than 10 degrees, indicating to use the Yellow Rated Capacities, marking an important step toward providing the operator additional safety information.
1995: The rise of electronics:
The increased market availability of industrial CPU-driven systems led to the development of load moment indicators (LMIs) for our cranes. These systems included electronic sensors for length, angle and luff cylinder pressure.
For the first time the operator could now see the actual lifted load and the rated capacity of the crane in its current configuration. Further advances led to the inclusion of motion limiters which restricted the operator when trying to lift over the rated capacity.
Fundamentals of articulated crane stability – forward tipping
The foundation of crane safety is stability. Forward tipping refers to a situation in which a crane becomes unstable and begins to pivot or tilt forward around its front axle or tipping line. This occurs when the combined crane and load centre of gravity shifts beyond the front stability threshold, typically due to excessive load, improper weight distribution, or uneven ground conditions.
Side tipping
Side tipping refers to the lateral instability of a crane where it begins to tilt or overturn sideways. This typically occurs when the combined crane and load centre of gravity shifts beyond the side stability threshold, due to exceeding the rated cpacity from uneven ground, excessive articulation, excessive boom tip height and load swing.
Stability standard – AS 1418.5
This standard established key benchmarks for crane stability. It used a tipping stability factor of 66.6 per cent for pick and carry operations to ensure that cranes operated within safe limits. Which effectively meant the crane would remain stable under static conditions up to 1/0.666 = 1.5 times the Rated Capacity.
2001: Deration Charts
The turn of the century saw the release of side slope deration charts. Up until this point the cranes load chart was based on flat level (up to one per cent gradient) ground, any deviation would require the operation to “reduce accordingly”.
Side slope deration charts gave the operator valuable information on how side slope reduced the rated capacity of the crane. The operator still had to understand and manually calculate the reduced capacity, hence it still heavily depended on an operator’s training and behaviour.
2013: Dynamic Load Moment Indicator (DLMI)
The advent of Franna’s patented Dynamic LMI system was a game-changer. Unlike earlier LMIs, which relied on preset capacity charts, Dynamic LMI incorporates real-time stability monitoring systems. This system uses a combination of advanced sensors and processors to continuously measure and adjust for:
• Chassis Pitch and Roll: Sensors monitor the inclination of the chassis, enabling the LMI to perform real-time dynamic calculations based on actual chassis operating conditions to maintain 66.6 per cent stability.
• Articulation Angle: An infinitely variable angle sensor, to precisely vary the geometry of the crane. This addition also increased the rated capacity over a wider range of articulation.
• Boom Angle and Extension: Real-time data on boom positioning ensures that the crane operates within safe limits, reducing the risk of overloading during extended boom lengths or high boom angles.
• Luff Pressure Sensors: To accurately measure the lifted load on the hook.
All these sensors, in combination with patented software application, allow the LMI to dynamically adjust the rated capacity for 66.6 per cent stability in real time, providing continuous information, allowing operators to adapt to changing conditions instantly.
For example, a crane operating on a side slope will receive real-time adjustments to its load capacity, reducing the risk of overloading and tipping. This gave the operator the precise rated capacity for the crane configuration and slope condition, eliminating the need for the operator to manually calculate from the deration chart.
Additional features such as automatic counterweight detection and LMI override timeouts eliminated much of the manual intervention, enhancing both safety and efficiency.
Stability Standard ISO 4305:
International standard ISO 4305 has further refined stability requirements, incorporating a five degree tipping angle to further account for operational dynamics. This shift brought a greater degree of stability for long boom lengths and high boom angles.
2024: Safety Radar
The introduction of the Franna patent pending Safety Radar system on the Franna Pick and Carry range of cranes represents a significant leap in safety technology.
Building on the Dynamic LMI foundation with real-time 66.6 per cent stability calculations, Safety Radar also includes the ISO 4305 Tipping Angle calculations giving a greater degree of stability for long boom lengths and high boom angles.
Safety Radar also does much more, it gives the operator valuable information to plan the next move. The previous Dynamic LMI system only gave the operator the rated capacity for the current configuration the crane was operating in.
But what happens to the rated capacity when the operator telescopes out, or articulates right?
Most operators understand when they increase radius the capacity of the crane reduces. But do they understand the difference between forward tipping and side tipping limiting rated capacity and how boom height and articulation effects this? Dynamic LMI could not provide this information.
Safety Radar takes it to the next level by providing the operator a clear visual representation of rated capacity changes in response to articulation and boom extension. The blue dot at the crosshair of boom length and articulation angle show where the crane is currently operating.
The Safety Radar visual shows where the crane can operate and the colour contours reflect the Rated Capacity Percentage. The truncated line of red indicates a rated capacity limited by side tipping. This is invaluable information the operator has never previously had available and allows the operator to plan the next move.
Safety Radar visual also gives the operator an understanding of how the rated capacity drops off more quickly in a side tipping limitation as can be seen by the varying thickness of the yellow zone for forward versus side tipping conditions.
Safety Radar is integrated as standard from the factory for Franna’s latest ADR compliant AT22-2, MAC25-5, and AT40-2 models and is available for complementary upgrade for all AT22, MAC25-4 and AT40 models delivered after 2023.
It is also available for retrofit on earlier model cranes. For further details of how Safety Radar works, view the YouTube demonstration video https://www.terex.com/franna/en-au/safety-radar
Lift Planner
The same technology that is used in the Dynamic LMI and Safety Radar systems is also made available in a web-based Lift Planner to allow a lift to be assessed and documented ahead of time.
The Lift Planner allows the user to select the machine model, lifting configuration and the LMI system fitted to the machine:
• Robway – AS1418.5 (Dynamic LMI) or
• Robway – ISO4305 (Safety Radar)
Both LMI systems use a minimum of 66.6 per cent stability factor, the main difference between the two is Safety Radar also includes the ISO 4305 Tipping Angle calculations giving an even greater degree of stability for long boom lengths and high boom angles.
ISO 4305 Tipping Angle calculations are currently only available in Safety Radar LMI system. It is important to note, when using the Lift Planner all pitch and roll inputs are chassis angle not ground slope. This means the user needs to add chassis/tyre deflection to the ground slope.
Chassis/tyre deflection changes depending on many variables – tyre pressure, articulation angle, boom position, lifted load as a percentage of rated capacity etc. Without any prior actual measurements, to be conservative it is recommended using four degrees ie the predicted chassis angle will be equal to the ground slope plus four degrees allowance for chassis/tyre deflection.
The cranes’ LMI system is actually more precise than the Lift Planner as the LMI system is using the actual live chassis angle for the condition the crane is operating at.
The predictive warnings, stability safety factors, and lift planning tools further streamline operations. These advancements not only increase operator confidence but also reduce the likelihood of accidents.
Commitment to zero harm
Franna’s driving philosophy behind these advancements is to achieve Zero Harm for crane operations.
Franna is committed to continuously improving its cranes and endeavour to provide intuitive human machine interfaces and technology to enable the safe and efficient execution of pick and carry operations – Safety Radar is a great example of what has been achieved as a next generation safety aid for Franna operators.