Lighter, cheaper trailers from Scammell
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• Production has started at the Basingstoke works of Scammell Lorries Ltd of a revised, rationalized range of Challenger S (single axle) and Challenger T (tandem axle) semi-trailers. These are designed to work with tractive units in the 24 to 32-ton articulated range, as were the previous Challenger models, but in addition to these there is also included a range of trailers for use at 34 tons gvw in anticipation of new regulations. These latter carriers will have a 2.05m widespread bogie as standard. The revised designs are, it is claimed, more competitively priced and lighter in weight—yet with no loss in strength.
A rolled I-beam section, 16in. deep and with flanges fin. thick and 5-1-in wide, is still used for the main-frame side-members, but it is now of stronger steel, of 24 tons tensile strength. This has enabled the slimmed neck portion of the forward-end of the frame (over the coupling) to be made more simply. The same thickness of bottom flange is now used throughout whereas before a separate, thicker strap had to be inserted into the neck section of the frame.
A full-width pressed-steel channel cross-member, ;tin. thick and with 3M. flanges, runs across both front and rear of the new chassis frame. The main intermediate cross-members are large diameter tubes welded between the webs of the side-members so that the chassis is given a high torsional strength.
Further bracing is provided by the full-width cross-bearers, of 4in. deep and Ifin. wide rolled I-section, threaded through the webs of its side-members near the top and welded in position. The cross-bearers are joined at their tips by specially rolled side raves of +in. thick steel.
One of the distinguishing features of the new Scammell Challenger trailers is the deeply gusseted headboard with a protective step above the box which affords protection for the air-brake connections on the front. The front ends of the chassis side-members project beyond the headboard to provide extra rigid support for it.
The rubbing plate spanning the underside of the chassis neck, where it rests on the fifth-wheel coupling is only tacked with weld to the lower flanges; stress-raising in this area is therefore avoided. Instead, the rubbing plate is stoutly backed by deep cross-members and it is these which • transmit the coupling load into the sides of the chassis frame's main girders.
When dual-purpose trailers—decked, but equipped with twistlocks to fasten down ISO containers—are specified, the container locks are supported on the ends of deep box-section cross-beams of full width, continuous span threaded through, and welded to the frame side-members.
Extra weight-saving can be achieved on the Rubery Owen suspension, which is standard on Scammell trailers, by specifying single-leaf springs. Two-speed landing legs are standard to support the front end of the trailer when detached from the tractor.
Weather-sealed Rubbolite junction boxes are a feature of the electrical system, as is the use of circuit breakers instead of fuses. The latest design of Rubbolite rear-lamp cluster, evolved specially for British Leyland group trucks, is fitted to the new Scammell trailers.