One of the most common mistakes made in load securing is the fact that the most important features of the tensioning equipment, whether belts, chains or ropes, are not implemented effectively.
These important features can be found on the belt label or chain/rope tag.
It is extremely important to know which data is to be expected for which backup method. The preload force (STF) is important for all force-locking securing methods. The lashing capacity (LC) is decisive for all form-fit securing methods.
Of course, friction also plays a major role in any securing method. This is particularly important for force-locking methods such as tie-down lashing. The method that is most frequently seen is where the biggest mistakes are made.
Practical examples
This picture illustrates the whole problem with lashing down. There are different coefficients of friction between all layers and the lashing angle changes in each layer.
This means that the required securing force, which results from the load weight, is nowhere near achieved.
In addition, the tensioning straps only have short lever pressure ratchets.
Some of them run over the dropside and are suspended from the frame.
This vibratory plate is also not adequately secured. The belt is guided over the side wall, which greatly flattens the lashing angle α and significantly reduces the vertical part of the securing force.
The belts probably run over the dropside because the vehicle was built for transporting bulk goods and has no lashing points. The vehicle would therefore not be suitable for such transportation.
Transportation of large appliances
Without calculating in detail, it can be assumed that the subsequent load is very likely to be inadequately secured.
Using the LC of securing devices is often useful when transporting large equipment, because larger masses can be secured with comparatively little effort.
Excavator transportation and construction site equipment are typical examples of this. But mistakes are made here too.
One of the most common mistakes is that the belt or chain is looped through the towing eye.
In this case, the chain only acts in the direction of travel, but not to the side.
This has the negative effect that the machine could slip sideways in the event of a swerving movement, thereby shifting the overall center of gravity of the combination. The result would be a coup.
This machine has three attachment points (yellow circles) and yet they were not used optimally.
The lashing angle α (red) is unfavorable because it is too large, the lashing angle β (blue) is OK. The securing forces in the direction of travel are considerably greater than those to the sides.
Diagonal lashing would have been the better solution without any additional effort, because both lashing angles transfer the forces optimally both lengthways and crossways.
It would also have been possible to attach both chains in the lashing eye.
Yours, Sigurd Ehringer
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Episode 27: What about the lashing angles?
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Episode 29: Discard maturity of lashing straps – The criteria
Tobias Kreft