In the first PTI Container Weighing EBook, published this April, 2016 the advantages and disadvantages of weigh bridges and twistlock based weighing systems have been outlined in detail.
Also, weighing systems installed on headblocks or in sheave pins versus spreader twistlock based systems have been discussed. One important fact to consider is that a weighing system installed on a headblock belongs to the crane, while a weighing system installed on a spreader is not a fixed part of the crane but of the spreader.
The spreader can be removed to install, for instance, a coil boom or hookbeam under the headblock. On the other hand, a headblock mounted weighing system does not allow determination of container load eccentricity as easily and as accurately as a spreader twistlock installed weighing system. It has already been voiced that the next regulation which IMO will issue on container handling will be on limiting the eccentric loading of containers which will require weighing systems with load eccentric measuring capabilities.
The other evident disadvantage of headblock based weighing systems is the impossibility to determine the weight of each container in twin-lift applications. I would like to elaborate on different possibilities of using spreader twistlocks to weigh containers and verify the gross mass. There are solutions with load cells around the twistlock or products with a sensor inserted into the centre line of the twistlock, like LASSTEC using fiber optic technology with a Fiber Bragg Grating (FBG), which provides high measurement accuracy, an ideal compensation for temperature variations and insensitivity to shock loads and electromagnetic interferences…
