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The Possibilities of

8th March 1932, Page 108
8th March 1932
Page 108
Page 109
Page 110
Page 108, 8th March 1932 — The Possibilities of
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CONVERTIBLE MUNICIPAL VEHICLES

A Modern Investiga tion of an Old Sub ject. The Problems Involved in Produc ing an Interchange able-bodied Vehicle

'17ER since the era of mechanical

4 1 ' road transport dawned, some 30 years ago, there has been at the back of many designers' minds the thought that a vehicle ought either to be built as a complete unit, like a ship, or more advantage should be taken of the fact that, in make-up, the chassis and body are separate entities. On the face of it, a twocomponent machine, that is a chassis and a body, is wrong in principle— at any rate from a production point of view—but a little investigation of the matter gives it an entirely new complexion.

Such an investigation hardly conies within the scope of an article F50 such as this, which is intended to show the possibilities of producing a chassis that would be capable of carrying several different types of body. It is sufficient for us to take for granted accepted practice and to recognize that, under existing manufacturing conditions, chassis building and body making are, in effect, two separate trades.

This brings us to the point enumerated in the opening paragraph—could not more advantage be taken of the methods of manufacture now employed and thus use one chassis to carry a.number of specialized types of body? Naturally, such a principle could be employed only

where the type of work undertaken by the operator—be it a municipal undertaking or a private concern—is wid e ly varied and the fleet of machines used is, comparatively speaking, small. In large undertakings the best course would obviously be to have a machine of each type, such as a van, tipping lorry, etc.

There are many difficulties in arranging for an interchange of bodies, and it is a matter of speculation as to whether they are all insuperable. One has to bear in mind that if specialized labour has to be employed to effect a change of body, such charges as are involved naturally militate against the saving effected by utilizing only one chassis, as against a number.

In a municipal garage there is usually a permanent staff, so that the question of labour charges is of less moment than in a private undertaking, where the work is not so varied in nature. Furthermore, facilities are usually available for the repair and maintenance of vehicles which would fit in nicely with the requirements about to be outlined.

Broadly speaking, municipal vehicles usually fall under one of the rollowing headings :—An open platform lorry, a tipper, a refusecollecting machine, a an which may be used for a. large variety of jobs, including the maintenance and relaying of electrical equipment, a water wagon and a lorry for carrying road-making material. Now, in nearly • every case the loads to be carried are commensurate with the employment of a fairly large vehicle, say a 5-tenser or G-tonner, and it is on such a basic that we have framed our proposals. • • As will be seen from the accompanying drawings, • a, karma' type of straight-framed chassis of medium length and height has been evolved, and in order to obtain a reasonably low loading height the diameter of the wheels has been reduced as much as possible. Twin tyres at the rear enable the full load to be taken without contravening any of the Ministry of Transport regulations, whilst a Mil-width forward-control cab permits a couple of men to be earned in addition to the driver— an essential item in municipal work —without trespassing upon the loading, space of the chassis.

Without a crane or hoist of some description the whole scheme would fail, but, again, ft may he mentioned that the equipment of most municipal garages is complete, and it is doubtful whether many corporation transport departments exist which are devoid of a crane. As an outside estimate, the weight of any of these specialized bodies should not exceed two tons and the hoist, being moderate, should be well within the capacity of any existing lifting machinery.

We can now turn to details of con struction. Ordinarily all types of body are bolted to their chassis and in nearly every instance a wood framing is incorporated on the underside of the freight container. This form of construction is hardly permissible in the proposed layout, because the framework of the body must be capable of taking care of the freight loads without the intermediate support such as is given in the ease of the normal type of vehicle with a fixed body. The reason for this is obvious.

A body that is quickly to be mounted and dismounted must have few points of attachment—the fewer the better, always provided that the mounting plates, or whatever form the connecting devices take, are substantial. Bolts and nuts must be avoided, because, for one thing, they become damaged and, another thing, they are liable to take a considerable time to secure properly, whilst care must be taken to ensure -that securing the attachment pieces is not a " fiddling " job, which would, in consequence, waste time.

There are, of course, many ways in which an attachment could be effectively made ; the method shown in the drawings is by no means the only one, but it is illustrative of how a simple design can in practice be effective.

It will be seen that beneath all the bodies two channels are arranged in such a way that they lie, just outside the main frame members of the chassis, with, of course, working clearance between them. To the underside of these body channels dowel pins are attached, the ends of which are tapered to allow of easy entry into the sockets built on to the chassisframe side members.

A certain amount of accuracy in manufacture is bound to be necessary, but once the body and chassis frames have ve been properly ma tettup there should be no question of misalignment occurring. Variation in atmospliQric temperature will, no doubt, have its effect upon the exact length between the centres of the holes in the sockets and the &mei pins, but it is most unlikely for the temperatures of the body channels and the chassis-frame. members to vary more than a few degrees.

It is clear, then, that, provided the work is carried out properly when the machines are first constructed, there should subsequently be no question of any of the " Matings " becoming wrongly aligned.

In the case of vehicles requiring tipping gear, the method of attachment is rather different. The rear part of the frame needs a hinged joint, whilst the fore portion demands merely lateral location to give all the necessary security. It would be stupid to suggest that the dowels would centre themselves perfectly• after every tipping operation, but it should be remembered that, under the conditions when lining up is necessary, the body is empty. Consequently, a lever applied between the frame members of the chassis and the body would soon centre the attachment pegs in the sockets.

Securing a Stationary Body.

For ordinary use spring cotters would seem to be all that is necessary to secure a non-tipping body to the chassis; they would be easy to fit and, if made of good-quality steel, should not wear unduly. In any case, the replacement of a dowel pin would be inexpensive and easy.

Criticisms might be made against the hinged attachment for the tipping bodies. A single' hinge-pin entered from the side should suffice to provide all the security demanded. If any difficulty in entering the pin be encountered, it should be a fairly simple matter to provide a plate packing piece at the rear, which will give the exact centres for the two elements. Thus, when lowering the body on to the chassis, the forward dowels would give longitudinal location, whilst the plate will give vertical location.

Although in one of the accompanying drawings a hand-operated tipping gear is shown, there seems to be no reason why a mechanical tipper could not just as easily be used. A drive could readily be obtained from the gearbox.

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Organisations: Ministry of Transport

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