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THE FUTURE OF METAL BODYWORK.
Page 97
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As the Steel Ship Has Ousted the Wood Type, So May the Metal Body Displace that Built of Wood. Some Typical Forms of Construction.
A SUBJECT which should be of considerable interest to all users of commercial-motor vehicles and to coachbuilders is that of metal bodywork and its possibilities. At the present time the wood body still holds its own end even with new construction this type predominates, but it remains to be seen whether this be due to the fact that bodybuilding in wood is an art which has developed during the course of many hundreds of years and is known to a great many workers who, if dealing in metal, might find themselves invading new terrain, or whether it be because the wood body has outstandingly good characteristics.
We are inclined to the belief that for many classes of work the metal body is quite as good as the wood body, and, sometimes, better, this depending upon the experience and designing ability of the makers. The metal body is really more of an engineering job than the coachbuilt pattern. It is a question of putting the metal in the right place and carefully working out the various stresses which it has to experience not only through the actual running of the vehicle but resulting from expansion and contraction consequent upon alterations in temperature, although these are of more importance in tropical clinics than in temperate zones.
In certain designs the practice followed closely resembles that employed in the construction of a steel ship, excents that riveting is often displaced by welding, and we all know how the steel ship has completely outclassed the old "wooden walls." It is too soon, however, to say whether this allegory will be carried out to its conclusion. As a matter of fact, very few bodies ostensibly constructed of wood are entirely so ; most of them are well braced by metal brackets, corner pieces and, in some cases, steel inserts, notable examples of this construction being the London General Omnibus Co.'s bus, where metal employed in conjunction with wood is carried right around the body, also in Strachan and Brown. Duple and Hall Lewis construction.
The protagonists of the metal body, and particularly that constructed of steel, claim for it that there is more elasticity, which -permits give and return, whilst the wood body gives but does not return ; also that this type of body can be made much lighter, strength for strength, than the wood type and be much more lasting. For instance, actual examples of 26seater all-weather bodies weigh 21-cwt. when Constructed in steel and something like 35-cwt. in wood. There is also the point of safety in the event of accident. The steel body merely bends under the effects of collision and does not splinter, although it may take a 'permanent set, whereas serious injuries are often caused through broken wood splintering into pieces with spearlike points. From the mainte»once point of view there is the advantage that bent or dented parts can often be straightened.
On the other hand, those who favour wood construction believe that the metal body is far more likely to drum and otherwise emphasize chassis noises and vibrations. Why this should be, however, cannot clearly be stated, for in nine cases out of ten the so-called wood body is panelled in metal, and it is the panels which usually cause any drumming which may exist, and these panels may be secured just as firmly in the case of a metal framework as with the wood framing, although it may be that wood pillars, etc., tend to act as vibration dampers. Considerable success is being obtained by the type of body in which the pillars, window frames, etc., are constructed in light alloy, these parts often being supplied in standard sections by such well-known makers as Anster, Ltd., Crown Works, l3arford Street, Birmingham, and Beckett, Laycock and Watkinson, Ltd., Acton Lane, Harlesden, London, N.W.10, but in this article we shall deal chiefly with the allsteel body, referring particularly to a novel and scientifically designed pattern which is being built by the Motor and Accessories Co., of 40, Waterford Road, Walham Green, London, S.W.6, which specializes in an all-steel body of the all-weather pattern, although fixed-head bodies can, of course, be supplied if desired. These bodies are built right on to the chassis frame, but care is taken not to weaken the main frame members, and no holes are drilled in the flanges. Each body cross-bearer rests on the side members, but is carried at its ends by neat brackets bolted to the webs of these members. Packing is inserted between the cross-bearers and the upper flanges of the side members. Small cross-bearers for the running boards are bolted to the cross-members of the chassis and the channels of the main cross-bearers are filled in with wood to take the floor. The arrangement of the pillars, which are all constrncted in welded steel, can best be seen by referring to one of our sketches. It will be seen that, at the top, each pillar carries 'three bolts which are welded to it, and these serve to carry the longitudinal wood members to which the lining of the body is attached. • Incidentally, if the exterior panels have to be replaced at any time, it is an extremely simple matter to remove these wood members; which do not form part of the main framework.
At the forward end of the body the running boards are not supported separately, but are hung from a cross-bearer, and the brackets on which they are carried , are provided at their upper ends with in-jutting pieces which press against the side members of the chassis some few inches below the level of-the cross-bearer. Each of these brackets adds greatly to the strength of the construction, ancl any pull on, say, the door pillar, merely puts tension upon the dress-bearer and compression upon the short in-jutting portion of the bracket, so that one can actually pull on the door pillar with all One's strength without any appreciable give occurring.
The sides of the door pillars are welded, but cast-aluminium Plates are riveted on, and the binges are secured to these plates by setscrews which pass through angle irons at the
hack so that they can be renewed with difficulty. A lead 4
or taper of in. is allowed on the width of each door pillar.
Each door is constructed on the principle of that of a safe. The complete door forms a box member of great strength and rigidity built up from only three pieces of steel -welded together. At the upper part of each door opposite the hinged side is a tongue or hook fitting into an eye on the pillar, both these parts being of hardened steel. When the door is shut they lock pillar and door firmly together and prevent any risk of the pillar pulling away from the door, as se often happens. At the bottom of each pillar on the lock side is also a large V-shaped rubber cushion fitting into a socket of similar shape on the door.
The exterior of each door is constructed of 20 s.w.g. leadcoated sheet-steel, whilst the inner portion is of 22 gaugesteel.
For holding the setscrews used •for attaching the interior panelling, nuts are actually welded to the metal of the door.
In eases where a drop glass is employed in the door, the rear panel is provided with a large circular orifice which gives access to the glass-actuating mechanism. In any case, holes are provided in the panel to give access to the screws which hold the lock and locking tongue.
In the all-weath body the bulbous fixed back portion is
made in one piece and lap-jointed to the lower panels„the juncture being riveted and covered by steel moulding, which also assists in strengthening the body. We noted particularly that copper rivets ace used for this work.
At the windows the panels are stepped, and the window frames are fitted from the exterior, the frames being bolted through to nuts inside the panels. In saloon vehicles setscrews are inserted into tapped holes in aluminium internal beading, as this gives a better finish.
By loosening a few screws any window in the fixed back can be removed complete with its frame.
All the external panels are in 20-gauge c.r.c.a.
To permit movement between the body and the bonnet, a floating dash is incorporated, the joint between the two portions being made by a greased-leather water exeluder, over which projects a cover secured to the scuttle dash, the point of juncture being concealed by beading.
A particularly interesting feature in the construction is that the rake of the whole dash can be adjusted from underneath the front of the body, as the dash pillars are supported at their bases by special brackets, the upper parts of which are screwed and fitted with nuts. TI-e adjustment of two nuts at each side alters the rake and thus allowance can be made for any setting which may occur in the aas8is frame. Such adjustments as these arc, of course, of a semi-permanent nature and might have to be done only once during the life of a vehicle.
Even the spare-wheel locker has a door of box section, this being made of two pieces only, and one of these includes a steel wire which constitutes the hinge pin.
The driver's stepboard is in one piece of 18 s.w.g. steel bolted to the pillar brackets. It also forms a support for the rear of the wing at that side.
The importance of accessibility has also been well considered, trap-doors of adequate size being provided over the axle for the full length of the cardan shaft and over the battery, whilst a toolbox of adequate size is sunk into the floor.
Each pair of seats is constructed of a single steel shape, with two springs for the back. These springs are carried above the cushion pan and then passed through holes in the back so that they are bolted to the rear of the squab holder. Wood shapers are provided fOr the squabs.
For securing the seats to the floor. lengths of angle steel are bolted to the last-named and each pair of seats is held by four bolts to these members.
The sliding glass in the driver's door can be removed by undoing six screws only, when the complete frame comes away. Rubber rollers are provided between the window frame of each door and the pillars, whilst tongued rubber strips are utilized on the hinged sides.
A simple device, but one which greatly feeilitates the Movement of the sliding hood, is the type of bracket used at the ends of each hoop stick. In the ordinary pattern where the stick remains upright, pull on it exercises such a leverage on the bracket that it tends to turn and jam on the runners,
but in the new type the portion carrying the stick is hinged, so that immediately the stick is pulled it assumes a horrzontat position and permits the bracket to be pulled along the runner without any tendency to jam. When brought over the wing-nut, the hoop stick is raised to the vertical position, when a fork at the bottom of the bracket fits under the wing-nut and locks the stick firmly in position.
Only a few months ago we gave details in this journal of the system of all-metal construction in light alloy employed by Short Bros. (Rochester and Bedford), Ltd., the well-known bodybuilder of Rochester. The materials utilized are aluminium and Duralumin, the latter being employed in those parts which have to take stresses.
It has been found that in a small single-deck vehicle seating from 14 to 20 passengers a saving of 30 per cent. in
body weight can be effected. For example, the body of a 20-seater bus built recently weighs only 11 cwt., against the 17 cwt. of a similar construction in wood.
It is unnecessary for us to repeat information already published, but we would refer our readers to the part-sectional drawing in which the method of flitch plating, etc., eau clearly be seen.
There are other claims for the superiority of all-metal bodies, and ene tf the most important of these is improved safety in the event of an outbreak of fire either when the vehicle is on the road or when it is in the garage.
So far asthe life of the metal body is concerned, it is probably considerably greater than that built in wood. There is no natural warping, and whilst steel may corrode unless properly protected by paint, the light-alloy body, is almost entirely free from trouble of this kind.