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Scammell sub frame option for 5th-wheel
Page 48
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• A specially shaped sub-frame for supporting the fifth-wheel couplings on tractive units, now being offered as an option by Scammell, is claimed to double the chassis strength at the point of maximum stress. The sub-frame spreads the stresses from the coupling and also provides reinforcement for the chassis frame, giving additional torsional as well as bending strength.
The side pieces of the sub-frame are of inverted-L section pressed from 0.3125in.-thick steel. The edge of each 6.5in.-wide top flange is vee'd back to the web of the inverted-L section by 0.25in.-thick plate. Bracing the two side pieces is an 11.5-in, wide and 3.5in.-deep top-hat section cross-member pressed from 0.25 in.-thick steel plate.
The coupling sub-frame is 46in. long and has separate 14in.-long tapered tail-pieces. These support the front-ends of the curved lead-in ramps over the back of the tractor chassis to aid trailer-coupling.