The Ideal Chassis for Publicity Bodies
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Scope for the Use of a Full length Unbroken Platform Area Contributes Towards the Desired End, and Modern Developments can be Used to
THE original object of building automobile bodies to conform, to some extent, with the laws of streamlining was to enhance the efficiency of the vehicle by minimizing its wind resistance. The practice, naturally enough, has hitherto been confined, mainly, to the private-car field, in which modern streamline design has often been criticized on the ground that the basic plan has not been followed. body designers having permitted considerations of appearance to outweigh those of the scientific ideal.
That some of this criticism is justifiable points to the fact that enhanced appearance is of greater practical value than diminished wind. resistance, If that be the case with private cars, it should be all the more so with commercial vehicles, the speed of which is so much lower, In our industry good appearance is extremely important for its advertising value. Accordingly, any factor that contributes to the attractive lines of the body is to be encouraged, and streamlining certainly achieves this object.
An accompanying illustration affords a good example of this form of publicity bodywork. It also gives an idea of the 'difficulties that have to be over-. come.. The special bodyis built around the chassis, the original design of which was not intended to carry such a structure. The chassis was planned for 'a body of conventional type, but, we ask, is it ideally suited even for that?
Whether sweeping curves, maximum capacity, or almost any special body characteristic be required, a chassis with an engine protruding at the front and a radiator perched before it is an awkward base upon which to erect a goods container which is efficient for its primary purpose and pleasing to the eye. If the body be a model, large Or small, of a commodity in which its owner deals, the case is all the stronger.
'Where no fanciful design of body is employed, the coachbuilder, as a result of long years of habit, might excusably a2fl be at a loss to know how to make a body front, if there were no radiator, and, indeed, for the same reason, the appearance of such a vehicle might be considered odd. There are, however, plenty of cases where this small difficulty has successfully been surmounted.
There are big compensating advantages to be gained, however, and few drawbacks. The radiator could be mounted at the rear under the body, inside or outside the frame, or, possibly, on the roof. In the last-named case, however, the long pipes would be rather undesirable. The difficulty of filling the water system is apparent, and it is not good to have what is essentially a chassis component carried independ ently. Otherwise, the idea of an oVerhead cooling plant. has seVenal attractions.
The obvious aim is to have a fiat area at about frame level, unbroken except by the controls. Accordingly, the power unit must he accommodated appropriately. Various methods have been suggested in the past, and the Conimer Pug is one example of how it can be done for goods-carrying, whilst for passenger tranSport the A.E.C. Qtype is an instance.
N.Ve reproduce an illustration that appeared in The commercial Motor ' ir. a recent article on a kindred subject. This shows a scheme for a rear installa tion. There is an almost inevitable sacrifice of accessibility', but with modern reliable engines this is not a serious matter. Moreover, if the particular object in view be publicity a slight loss in another direction is not a big price to pay.
The horizontal type of engine is strangely slow to develop, largely, perhaps, because of the difficulty of accommodating it. Mounted in the frame with a longitudinal crankshaft, the engine is inaccessible in respect of the cylinder head, whilst if placed transversely the transmission present's a problem. The drive has to be taken around a second 90-degree corner, unless the unit is placed at the back so that the crankshaft can be geared: to the axle, which would obviously have to be of the cardan type. Then, direct drive in the sense in which the term is commonly used is unobtainable.
The axial engine offers a perfect solution of the problem, and with.the knowledge that the Bristol company , has obtained encouraging results from its power unit of this type, one is more inclined to predict that, in this way, the ideal chassis of the future may eventuate. The advantage of an unbroken platform area is afforded by the batteryelectric. The traction motor is conveniently housed within the confines of the frame, and the accumulators are as easily accommodated well below floor level.
The sloping front and rear of the streamlined body represent a considerable sacrifice of useful space, but, on the one hand, there is rarely any stringent limit to overall length—a short wheelbase is more important—and, on the other, the same argumept applies as in the case of accessibility.
A more difficult problem is the rear door. If the operator be content with only a front entrance, it does not arise; if not, a side door can be incorporated without seriously spoiling appearance, although an unbroken panel is certainly desirable. Where a rear aperture is essential, there is no insuperable obstacle in the way of employing a roller shutter, particularly in view of the fact that the Brady concern now embodies a window in this form of equipment.
This, however, is a matter of bodywork rather than one that concerns the chassis, and there are still the controls to consider. Steering is a simple matter, for the driver must sit as near the front as is practicable, and the wheel can be mounted appropriately. This position will not involve any • appreciable deviation from the normal design of drag link or other items of the layout.
No difficulty is constituted by the hand-brake, and the pedal for the ,foot system can be arranged in any cOnvenient position in an assembly with a . Lockheed master cylinder, the pipe lines • eliminating all complications that might otherwise ensue on account of crosssisafts, rods, and links. A similar form • of hydraulic actuation could, if necessary, he adapted to the clutch.
The ideal gearbox, from the point of view of control, is one that can be electrically operated, such as the Cotal. Then, wherever it was mounted in the chassis, only electrical cables afe required to connect it with its lever.
Amongst recent developments there are many that can be profitably employed to facilitate the task ,of designing the bodybuilder's ideal chassis.