Curtainsiders without walls
Page 19
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• Lawrence David has launched a curtainsided 13.6m semi-trailer with a self-supporting roof and no intermediate pillars.
Its strength comes from a tapered steel pressing for the cant rails under the roof edges: these deepen toward the rear where they are joined to the rear frame, which anchors the whole structure. The wide spread of the rear frame is bolted to the steel floor frame and the trailer chassis. Although the floor slopes down at the rear the roof line stays horizontal to give a constant loading aperture height. Unladen weight is 7,460kg.
The front bulkhead is aluminium planks braced by deep top-hat sections with tapered flanks. These outer pillars provide the strength to contain the load, while their wrap-around sections smooth the airflow around the leading edges. A rounded top cross rail also helps the trailer aerodynamics; according to Lawrence David a streamline fairing is not necessary.
A more orthodox design is also available with cant rails parallel to the floor and quick-release sliding mid-pillars. To ensure a flush floor the midpillars nest over the floor side rails.
Strain relief is built into the front bulkhead joints using stiff rubber pads. This allows the trailer to flex without overstressing the bodywork. It also absorbs energy in a frontal impact to minimise damage. Cast aluminium cappings will protect against damage from overhanging branches; at the rear the lamps are recessed into the underrun bar.
The unpainted body with curtains and load restraint costs £4,800.