Curtain call: 1
Page 34
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• I would like to pass some comments on Mr Tonge's letter (CM 1248 Dec 1991) which may help him feel more comfortable when driving on our roads. Lawrence David has been a leading manufacturer of commercial vehicle bodywork specialising in curtainsiders for over 17 years and can assure him that all Lawrence David bodies are built to comply with the DTp Code of Practice: Safety of Loads on Vehicles which requires that a vehicle body must be able to restrain a force equal to the full weight of the load in a forward direction, and half the weight of the load in the sideward and rearward direction.
Further requirements are embodied within BS5759, which relates to curtain sides, and here one should point out that the curtains are in fact a series of load restraint assemblies bonded into a weatherproof cloth cover.
These call for, in the case of road transport, the rated strength of the webbing assemblies to be at least equal to the weight of the load with a 2:1 safety factor being used to calculate the webbing assembly strengths. These assemblies are tested using a direct tensile pull and the term "assemblies" relates not only to the webbing but to the buckle, the bottom strap, the rave hook, the top D-ring or equivalent, the rollers and to all the stitching and fastenings which bind the parts together.
Reputable manufacturers can demonstrate that they meet these requirements, and typically a semi-trailer carrying a payload of 25 tonnes will have 19 restraining assemblies along each side, given that they are rated to at least 678kg, meaning they have been proven under test to at least 1,315kg.
Operators frequently incorporate further load restraint within the bodywork where the payload may be of an unstable or irregular nature. Properly constructed bodywork is at least as safe as roped and sheeted loads, and a great deal easier and more pleasant to use. Lawrence Marshall, Managing director, Lawrence David, Peterborough.