Alloy Castings Used in
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A New Lightweight Cab
ADRIVER'S cab built in light alloy, of highly original design and construction, has been brought to the series-production stage by E. W. Campion and Sons, Ltd., Leicester The most interesting feature is the use of alloy castings in building up the front end.
The Campion concern, which specializes in van bodies, started to construct them of light metal immediately after the war. This decision was dictated by the extreme shortage of well-seasoned timber and other materials needed for the orthodox method of coachbuilt body construction. Moreover, the few skilled coachbuilders remaining available were occupied in repairs to existing vehicles.
Three Castings
The front end of the new cab is built from three castings in Noral 160 alloy, and the windscreen frame is a one-piece casting. Leftand right-hand units are secured to the ends of the frame, each unit being a single casting which forms a door pillar, windscreen pillar, scuttle side member and aperture for a glass panel.
A great deal of careful thought has gone into the design of the cab, in order to make it adaptable to a variety of bodies. Apart from the castings mentioned, alloy angles and extruded sections in heat-treated Noral 51 SQ are employed in building the frame skeleton. Panelled with alloy sheet, the ensemble is extremely rigid.
Side members of the door frame are made from extruded-section angle, with a wide flange on one side of the angle. This flange is milled to take the curvature of the door panel. The panel itself is stiffened on the inside by a broad
A32 strip of alloy sheet with a central web.
The three castings which form the front end of the cab are bolted together; lugs are arranged at the top and bottom of the windscreen frame to correspond with flanges on the sidemember castings. A good point in design is the marked reduction of the usual "blind spot" at each end of the windscreen, caused by the combination of side pillars and screen frame ends.
When used in conjunction with a Luton pantechnicon body, the stiff, extruded-section members at the top of the cab frame, together with the top edge of the windscreen, form a foundation for rubber strips which ensure flexibility between cab and body. When arranged for normal use as a cab only, a panelled roof of sheet alloy is fitted, but if access from the cab into a van body be required, side panelling to an extra depth of 12 ins, is added and the normal type of roof assembly retained.
The use of aluminium-alloy castings may, perhaps, give rise to some doubts among coachbuilders who think in terms of past standards, for such castings were not always capable of withstanding much stress. To-day, the position is entirely changed, as a mutt of progress in metallurgy and the vast increase in technical knowledge gained during the war years.
The frame skeleton for the Campion cab is erected on a jig, as also is the complete roof component. Door handles are recessed into the panelling. whilst hinges are bolted up in recesses cast in the side -pillar members. The weight of the complete cab, which is a full three-seater, is 2 cwt.
Cwt. Saved This is, of course, slightly heavier than would be the case if extruded sections or pressings were used, instead of castings, but vastly lighter than a cab of orthodox construction. While.we were visiting the works at Leicester, Mr. R. A. Neaverson, works manager of E. W. Campion and Sons, Ltd., showed us an 18-ft.6-in. pantechnicon, in which 1 cwt. had been saved by the
use of the cab design. • The company's system , of construction is the subject of several patents, which are pending at the moment. It is probable that the special extruded-section alloy side members of the door frames will eventually be replaced by castings, as these have proved so successful in building the front end. Ordinary sand castings are used at present, for the employment of dies could be justified only by really large series production.
Apart from the original driver's cab design, Mr. Neaverson showed us many interesting examples of Campion lightmetal bodywork under construction. The system of building up bodies from pre-fabricated components, or partial assemblies, employed at. this works, differs from that used by other coachbuilders, both in France and in this country.
Sections completed before erection are much larger, and the framework is panelled before erection. Although this system may not appear to be strictly economical, Mr. Neaverson explained that it results in a marked reduction in man-hours. This, having regard to the high rates of pay now ruling for panel beaters and others, means in the long run an actual saving in cost.
Large Units The entire side of a van body is constructed as a unit, whilst roofs are built in two sections, except in the case of a very long pantechnicon body, where a third section May prove to be necessary.
Top-hat extruded sections are used for the framewOrk and—an interesting point—the curved end members of roof ribs are light-alloy castings. Popriveting with hand-operated tools is employed for the panelling, a method borrowed from aircraft constructional practice.
While going around the works we noticed a particularly good example of van .body for the delivery of biscuits. Mounted on a Commer Q.3 chassis, with a 12-ft. 9-in, wheelbase, it has an internal capacity of 500 cubic ft. The Campion method of building prefabricated body sides in one unit, and roof in two sections, is employed, and we noted the great rigidity of the top rail. This is formed from two top-hat extruded sections joined together.
Extra Floor
Each of tjte van side components has seven pillars, and racks are arranged for empty biscuit tins, so that these can be shot forwards. As in other Campion bodies, the floor is of heavy gauge alloy sheet, with rectangular corrugations. One advantage of this sheet is that, when dealing with heavy loads, the floor thickness can be readily doubled, as the corrugations fit exactly into one another.
, Mr. Isleaverson paid a special tribute to Northern Aluminium, Ltd., of Birmingham, which supplies castings for the cab. He said that this company had given valuable assistance in the way of technical advice. •