Stronger chassis from Merriworth
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A STRONGER chassis with greater resistance to bending but with extra flexibility in twist has been introduced on Merriworth semi-trailers.
The new trailer has been designed for a gross trailer weight of 32 tons, which means that it can opeiate well within maximum weight limits on the Continent without overstressing. A high degree of standardization means that a faster production flow can be created for both home and export vehicles.
The chassis has been given a 16 per cent increase in deflection stiffness and a seven per cent lowering of stress by using 0.75in thick bottom flanges for the 19.25 in deep 1-section side-members. The top flange remains 0.5in thick.
Cross-members of the new chassis have been arranged so that two stiff sections — over the suspension and over the fifth-wheel coupling plate — are connected by a more flexible centre section.
Merriworth points out that leaf-spring suspensions do not yield much, which means that it is easy to put excessive twist into the kingpin coupling and intermediate cross-members if the wheels on one side roll over a hump or very high kerb. Putting some twisting ability into the centre section of the chassis relieves such strains.
The four-spring, balancebeam suspension is of Merriworth design and features 3.5 in wide six-leaf springs.