TECHNICAL IMPRESSIONS AT THE CAR SHOW.
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The Trend of Design of the Private Car and Its Effect Upon That of the Commercial Vehicle.
IT has been said by some that the design of the commercial motor could, with advantage, be brought nearer in line with that of the private car. This is probably the opinion of those who are familiar with the very high standard of reliability and efficiency to which the private car has been brought, rather than the opinion of those who have had practical experience in the design and maintenance of commercial motors. With the exception of the engine and a few other points, it would seem that the problems of private-car design are entirely different from those which arise in the lorry.
Taking the general trend of design at Olympia, one can find only a few points in which the design of the private car and the lorry keep close company. We may go farther than this and say that there are many components of the commercial vehicle which have been adopted simply on account of their design having been found satisfactory on the pleasure car and without a great deal of thought having been given to the conditions under which the business vehicle has to work. In many cases a clean break-away might be beneficial. With regard to the engine itself, it is quite possible that If private-car practice were more nearly approached, better results would be obtained. Many engineers who are competent to judge consider that the lorry engine is often too heavily built, especially. in its reciprocating parts, and that the designer, in his effort to construct a strong engine, has actually made one that knocks itself to pieces through the weight of its moving parts.
It is evident that the problem, which is yet unsolved, as to which is the most perfect form of rear axle for commercial vehicles is equally unsolved in the private car. At Olympia this week cars may be seen in which torque tubes are fitted and claimed as an advantage, whilst in other models of the same type and style of car the torque is taken entirely on the springs. Radius rods may be seen on some models and not on others. Torque rods with springs at their front ends are shown In some cases, whilst the torque is rigidly taken in others.
As the models referred to are, in most -cases, shown by firms of repute, it is evident that no one system can have any outstanding advantage-ever-the others, as if
this were the case the various makes would have fallen into line by now.
Neat appearance and silent running of an engine are, undoubtedly, the main points which have to guide the designer of a private car. Casting the cylinders en bloc and tucking away out of sight every working part are the main features of most of the engines shown. From the point of view of the man who has to keep a fleet on the road such features do not, however, always recommend themselves as being good to adopt. Simplicity and ease of access are the features which appeal to such a man. With regard to silent running of engines It is, however, evident that more attention will have to be given to this point in future in the design and construction of engines for commercial use.
The high speeds attained to-day by commercial vehicles, speeds which are maintained for hours at a stretch, call for more silent-running engines. A man driving in the cab of a lorry will always favour a silent engine and intending buyers of lorries will insist on a less noisy outfit.
The multi-disc clutch is that which is mostly tO be seen at Olympia this year. The unit construction of engine and gearbox is in evidence, but is by no means universal. This form of design produces neatness of appearance, but is not always favoured by the man who has to k-cep things in repair. It is not accessible.
Many of the gearboxes where they are separate from the power unit are situated far behind the engine, with
cardan shaft and universal joint connecting them. It has been thought by some that the unit construction would become almost universal, but the present Show proves this not to be the case. The position of the gear lever, whether central or at one side, still remains a matter of taste.
As with other points, there seem,s to be no falling in line in the matter of suspension, springs of all kinds being well represented. Half-elliptic; quarter-elliptic and cantilever springs are to be seen on the various models.
Generally speaking, the trend of the Show is towards small refinements and attention to details, and there is but little that could be copied with advantage in th construction of the commercial" motor.