Cargo movement and deformation of securing devices
Direct securing, which is justifiably
regarded as highly effective, inevitably involves movement and/or deformation
of the cargo. However, tolerable limits for such movement or deformation are
not specified anywhere. They nevertheless exist and agreement should be
reached. It would then, however, be consistent to allow the same movement
latitude to tied down cargo units. The potential of frictional securing, which
is itself associated with drawbacks, could be further exploited as a consequence.
The deformation brought about by
development of force in portable securing devices may straightforwardly be
calculated with sufficient reliability. Obtaining comparable data for fixed
fittings and attachments on loading areas, such as sidewalls, end walls and
stanchions is problematic. Enquires may be made of the vehicle manufacturers.
Taking account of cargo movement and
deformation of securing means, the calculation of which has been demonstrated
in a number of examples, demonstrates the worrying order of magnitude of the
above-stated shortcomings in conventional calculation methods in both the
positive and the negative direction.