New Constructional Features in
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ALL-METAL BODIES
IN passing from the offices to the Midland Works of the Metropolitan-Cammell Carriage, Wagon and Finance Co., Ltd., at Washwood Heath, Birmingham, a visitor may notice a most unusual railway track, consisting of seven different rails and providing a choice of six different gauges.
This indicates in obvious fashion the world-wide nature of the company's trade. If that visitor be then taken, as was our representative, for a railway journey through the works, he will have some idea also of the size of this concern which, indeed, has five large factories in the Birmingham area alone.
When it became known some time ago that the Metropolitan-Cammell Company was turning its attention to the construction of all-metal bus bodies, much interest was naturally aroused, but not until the new designs had passed through extensive tests was it possible to publish details.
Last Wednesday there gathered at the Midland Works a large party, consisting of representatives of well-known vehicle builders and operators, both municipal and private.
After lunch, at which the company's vice-chairman, Mr. A. Spencer, presided, the party was given a demonstration run in a bus having an all-steel double-deck body ; the chassis was a Dennis Lance. Contrary to the expectations of many, drumming was practically non-existent and, although the roads traversed were for the most part commendably smooth, it must be said that the body was extremely quiet and comfortable.
Probably the most interesting individual feature of the design is the formation of the pillars. This may be described as a combination of a channel, a T section and a square tube, the result being a member of small weight but possessed of considerable resistance to torsional and bending loads.
To produce it, a 2-in, diameter steel tube is drawn to the required shape and consequently the metal is continuous right around the section. Another advantage of this arrangement is that the flanges provide a convenient anchorage for the panels and brackets.
Starting at the bottom, the channel-section steel crossbearers are riveted to the longitudinal members, which are
steel angles. Steel gussets are used to connect the crossbearers to the special pillars already described and these are tied together on each side by means of a light aluminium rail at the bottom of the windows.
At a point some distance below roof level, they are again connected by a steel angle cant-rail and, in the ease of the single-deck bodies, aluminium brackets and angles carry the roof. In the double-deckers, however, the roof sticks of the lower saloon are of the same steel sections as the pillars, the top roof construction being similar to that of the single-deckers. In passing it may be mentioned single-deckers.in a double-deck body the pillars are not continuous from top to bottom, but the upper part is built as a separate unit, which is bolted on to the lower part.
Much of the strength of the body is, however, due to the 20-gauge steel panels riveted to the pillars on the broar flange which is innermost. They are thus in a comparatively protected position and, except in the case of a majm accident, they are unlikely to be damaged.
On the outer sides of the pillars aluminium sheets arc used. These carry no load and are not so much a part oi the structure itself as a covering for it. Should any oi all of them be damaged, nothing more than the appearance of the body will suffer. In consequence, the bus can continue in service until it is convenient to replace the damaged panel: by new ones.
Nevertheless, it is desirable that the replacement of c damaged panel should present no difficulty and this b ensured by the method of attachment. The channel of till pillar section faces outward, and in this a wood fillet held by means of screws which pass through the sides o the channel. To these fillets the outer aluminium coverim is attached by means of wood screws. If a moulding o waistline be required for the sake of appearance, it can h attached to the aluminium by means of screws passel through from the inside, so that the screw heads ar concealed.
Lest it should be thought that this all-metal constructioi must result in excessive weight, it should be noted that 30-seater single-deck body to suit an A.E.C. Renown chassi turns the scale at 1 ton 11 cwt., whilst a 49-seater doublo deck body for a Regent chassis is said to weigh 2 tons 9 cwt i.e.. just 1 cwt. per passenger.
It is understood that trial bodies of this type have, fo many months, been in service in London, Birmingham an elsewhere, with results which have led to the placing c substantial orders.