|188.8.131.52 Overheight and overwidth cases on flatracks, example 3|
Inadequate load distribution and securing of three wooden cases on a 40' flatrack
Steel strapping tie-down lashings have been fitted. Since simple plastic cornerpieces have been used, the steel strapping will press into the wooden boards of the case top under load and its pretension will gradually diminish, resulting in the loss of its securing action. With a steel strapping lashing length of 7 m, pretension would drop to zero if the strapping were to press into the top boards by only approx. 10 mm.
Another problem is that the front case is overwidth and is nonetheless secured with tie-down lashings.
Securing by the wedges nailed in front of the cases has virtually no effect, since the effective height of wedges (1) and (4) is minimal and that of wedges (2) and (3) immaterial.
Use of very close fitting wooden bracing ensures adequate lengthwise securing:
Heavy-lift cornerpieces, as shown at (1), are rigid and allow prestressing forces to be maintained under favorable conditions. It is better to use edge protectors of a resilient material with good recovery properties - such materials, as with a piece of tire at (2), allow maintenance of pretension under usual carriage conditions.
The load distribution on the flatrack contravenes the regulations outlined in particular in the CTU packing guidelines, which state:
By calculating the moments, the best position may be determined for the cases. The Figure shows roughly how they might be packed and secured:
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