The now available LASSTEC Container Load Sensing and Accident Prevention System is able to detect this potential accident situation and it can either alert the crane operator of the danger or interact directly with the crane control system to immediately stop the hoist mechanism. At the same time during the lift, the LASSTEC system also accurately weighs the container and determines any load eccentricity.
Trailer lifting detection which is achieved by a software extension within the LASSTEC control unit, requires no additional hardware to the standard patented twistlock load sensors.
The LASSTEC system continuously monitors and compares the load sensors on all twistlocks while the container is being lifted off the trailer or railcar. If one or more sensors detect a continuous weight increase after the container is initially lifted, the control unit immediately sends an alarm signal. At constant hoist speed, this is accomplished within a maximum 1 m of lifting height – quick enough to prevent major damage.
According to Beat Zwygart, LASSTEC’s managing director, the LASSTEC Container Load Sensing and Accident Prevention System, which has proven its effectiveness in major terminal operations all over the globe, offers a combination of capabilities, unique in a single package:
• Weighing of containers to an accuracy of 200 kgs, even with twin lift spreaders. Weighing of all containers is expected to become mandatory under new regulations to be issued by the IMO
• Determining load eccentricity: particularly important in mobile harbour crane, straddle carrier and reachstacker applications and crucial to avoid road truck axle overloads
• Detecting snag loads when containers are still attached to the stack below or if interlocking twistlocks are jammed
• Detecting twistlocks not properly engaged in the corner casting when lifting containers
• Monitoring and recording twistlock load cycles and overload occurrences to allow for targeted and therefore longer, more economical replacement intervals.
All of these functions, plus a new trailer lifting detection, operate during normal container lifting actions with virtually all spreader types. The LASSTEC controls interface with any modern container handling equipment and using solid-state fibre optics technology, the system is maintenance-free and needs no re-calibration during the life of the twistlock.
Zwygart also points out that unlike the LASSTEC system, optical scanners sometimes installed on RTG/RMG/ASC cranes often only capture lifting situations where the entire trailer is lifted – not if it is only being lifted at the front or rear.
In addition, “our system does not depend on clean lens, which can be a problem in dusty or humid environments,” Zwygart concluded.