Body Integral with Chassis the next weight-saving step
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No Deadweight, Other than the Payload, Should be Permitted. The Body Should be More than a Receptacle, Contributing to the Strength of the Whole
THERE is an increasing trend in car design to combine body and frame in a unit with the necessary components--engine, gearbox, and axles—suitably mounted in their respective places, and there is much to be said in favour of this plan. It is, indeed, a more. logical method than building a chassis and then adding. a body, which duplicates to some extent certain of the chassis functions.
Bodies do not, as they; should, add to the strength, and, therefore, the efficiency, of the vehicle' as a transporting unit.
Body Not "Pulling Its Weight."
Put in anothel-avay,.we know that a chassis, as turned Out by the iiianufacturer, is tested with a gross load, i.e., body plus pay-load (admittedly concentrated), in excess of the weight Of goods the complete vehicle. will carry. Is it not more lOgicai that, if the body be playing its part as a portion of the completed vehicle, the chassis alone should not be capable of carrying such a weight?
It would seem, then, that our chassis are designed in such a manner that the addition of a body--apart from its useas a container for a scattered load • or from any:aesthetic or publicity valtieit may possess_
.actually. 'detracts'. from the efficiency • of the chassisas a machine. By sug
gesting, recently,.. that all, that was needed was a box . or platform to carry the load, Capt. J. B. Walton, of Unilever, Ltd., raised a storm of protest-. Nevertheless, the normal body is no more than that.
Non-standardization a Difficulty.
At the outset, it must be admitted that the private-car manufacturer is in a stronger position to produce a frameless vehicle than is the commercial-motor maker. Cars are so nearly completely standardized that purchasers, in the main, are not allowed any whimsies, other than preferences as to colour, in the matter . of bodywork.
With few exceptions, the manufacturers in our industry are called upon to supply something in the region of 50 per cent, of their output with bodywork that is special to some degree. . Such . a consideration, although a drawback, is notan loan perable .Obstacle to . the design of frameless -vehicles, lint. calls for. care in designing ...to cover a range of wheelbases on chassis of the same basic type.
Whilst the franieless cars already on the market show the possibilities of the idea, the treatment of the problem on the cominercial, side would require to follow different lines. The strong pressed-steel or cast-aluminium construction of the car: body is not possible with. lorries or large vans, and even with buses of 'moderate size would be too expensive to produce..
Accordingly, we are left with two likely methods of chassis modification for securing reduction of weight, and, at the same time, making the body more integral with the chassis.
Side Members Unnecessary at Centre.
We could, for instance, use a cruciform-braced chassis and cut out the central portions of the side-members between the arms of the crossmembers, leaving parallel portions, fore and aft, to take the engine and front axle, and the rear axle respectively. Such a chassis would sit down . in the middle" if loaded up without its body, but by suitably strengthening the bottom body sills the complete ensemble could be made thoroughly rigid and up to its job.
The less orthodox and more satisfactory method would be to employ a stiff body assembly, containing, within itself, most of what we commonly know as the chassis frame, and to add front and rear-axle units in bogie form. With the engine at the front, a forward bogie assembly, comprising engine, gearbox, and a driving axle, mounted as a unit, could be designed to be satisfactory for all except the very heaviest service.
The problem of wheel adhesion could be overcome by mounting the engine well forward and the axle well back, a design which is less repugnant on mstlietic grounds than it was a few years ago, people having become accustothed to the bull-nosed type of vehicle.
This layout is also suitable for use with the two-front-axle vehicle which is becoming increasingly popular. In this case -both front axles, or only the centre one, could be driving axles.
Whilst the front bogie would be rather complicated With such an arrangement, the rest of the Vehicle. would be simple. There seems no reason why the bogie should not be easily accessible.
;Engine Part of Driving Bogie.
The possibility of another variation of the same idea ii opened up by the interest being 'taken in 'fiat, horizontally opposed multi-cylindered engines. Here the engine, gearbox. and driving axle would unite to form a rear bogie, ready to slip.into place in the chassis -frame cumbody assembly, with the front axle or bogie at the other end.
No problem of driving-wheel adhesion arises with this layout, the tendency being rather that too. Much weight is at the rear. To offset this, the driver's seat could be far forwards, with no overhang in front of it, so that the load could be carried well over the front axle, which could be brought rather far back to give proper weight distribution.
Early Developments Likely.
The frameless vehicle is no new idea in these pages, but the seeds The Commercial Motor has planted seem now likely to develop into bearers of fruits. As a means for saving weight, the integral body and chassis will become a major issue before long.
There is more than one bodybuilding concern now concentrating attention upon combining the body and the chassis into a homogeneous whole, installing the components as the body is built on the production line, and covering a limited range of body styles.
Unorthodoxy is now less suspect than in the past, so that the field is. freely open to all manufacturers who will look ahead. F.L.J.