THE MOTOR LOB OF THE FUTURE.
Page 10
Page 11
Page 12
If you've noticed an error in this article please click here to report it so we can fix it.
Have We Achieved in Design? No!
A SHORT TIME AGO fhe writer put forward in
these columns, under the title "Lessons from the War," certain ideas and deductions based on the experience gained from war service and its effect on motor lorry design M general. It was shown that, in the Writer's opinion, the performances of the vehicles turned out in large number's by several of the leading makers have been so uniformly satisfactory, making due allowance for the arduous nature of the work performed, that little change in design need be and is to be looked for in post-war models, always excepting those of certain makes which are of a type that is rapidly becoming obsolete. The question as to whether or not we have now evolved a type of design, which is so nearly perfect that no radical change may be expected in the future, is, however, a very different Matter, upon which the writer did not attempt, at the time, to express an opinion.
Since the above-mentioned article appeared, an inducement to refer to this larger aspect of the subject has been afforded, by reason of the fact that the deductions reached have, apparently, conveyed an impression to some readers that the writer considered the modern worm-driven type of lorry to represent the practical limit of engineering achievement in this direction.
"The Inspector," in the course of some interesting remarks in the issue for 2nd May, gives expression to this opinion and, incidentally, refers to the present writer's article as substantially tending to support his views.
It should not be forgotten, however, that the attainment of what, at first sight, appears to be 4 aatisfactory degree of finality in any.branch of human endeavour is, nearly always, ultimately shown to be, not this elusive goal at all, but merely a step or stage in that direction, from which, presently, we move on to fresh progress, perhaps to an extent undreamt of by those pioneers who were instrumental in solving the initial difficulties of the earlier stages.
As an example let us take the case of the evolution of the ocean steamship: How many times have we been told of the achievement of finality here, either in size, speed, or propelling machinery, only to find the prophecy belied shortly after by some new invention or the larger application of an old one? For instance, the change from reciprocating to turbine engines was surely somewhat of a blow to the finality theory.
Again, consider the recent invention of the hydroplane, which completely revolutionized our ideas as to the possibilities of speed on the water. Turning to military engineering and, particularly, the science of gunnery, not so long ago we used to speculate as to whether a mile or two could be added to the effective range of our large naval guns. Then (.` overnight," as our American cousins would put it, our scientific enemies astonish us with a few practice shots fired on Paris from a range of nearly 80 miles, thus, at one step, trebling the limit hitherto achieved_
Surely this kind of thing should Make us vezy chary of prophecy as to the limits of progress in any branch of engineering.
The writer's personal opinion is that there is no such thing as true finality in any branch of human endeavour, but, before we venture any further into this subject, it would be well if we attempt. to define what we mean ..by finality as applied to the particular branch of engineering with which we are dealing.
It is almost superfluous to state that by finality, generally, we mean the attainment of the ideal, or the nearest ptacticable approach to the ideal. What, then, are the essential features of an ideal vehicle for mechanical road haulage likely to be? We may, perhaps, get a clearer idea on this point by attemptmg to describe what particular and familiar features it will not possess. In the first place, it will not be provided with a prime mover, or power plant, which absolutely wastes a large proportion of the energy contained in the Inel. burned, as does the modern petrol engine, even the most skilfully designed. Neither will it have an elaborate and extremely vulnerable, not to • say troublesome, water cooling system, designed to dissipate that large proportion of heat or •potential energy of the fuel which the imperfect engine of the present day cannot transform for us into useful work. Surely posterity will smile indulgently at this enormous waste, which is, strangely enough, calmly accepted as a necessary evil by the average motorist. Secondly, we shall not have a type of engine containing numerous reciprocating .parts working at high speed and, therefore. causing vibration and wear and
demanding constant attention to keep them in a reasonable state of efficiency.
Again, and most emphatically, our ideal vehlee will not have a system of transmission which eat,. ,s a driver who is not skilled to produce the most earsplitting noises, resulting from violent clashing of gear wheels in his frantic endeavours to' hasten the progress of his vehicle from a speed of, say, two miles per hour to double that figure almost instantaneous4,
The step up gearbox which makes this possible is alone sufficient to prevent the present type of vehicle from being considered for one moment as anything like ideal. It is, probably, one of the most hideous mechanical abortions tolerated in modern mechanism the reason, of course, being that nothing better has yet been perfected.
• There are other features which will not be found on the ideal motor lorry : for instance, a transmission system which, apart from the drawbacks mentioned above, contains numerous friction-producing elements, all of which have to be carefully lubricated, failing which they will wear with alarming rapidity, Further " impossible " components are springs —which "more or less " intercept road 'shocks and tyres. which merely attempt to. perform the same function, viz., those of the solid rubber variety.
When we think of these points, all or most of which are to be found incorporated in the standard lorry of to-day, with the idea of perfection prominent before our minds, can we he otherwise than convinced that, although we have at hand a motor vehicle which is satisfactory in its way and represents the best that can be produced in the light of mechanical progress up to the present, yet we must net, on that account, give up hope of further improvement.
The true engineer does not sit still and accept any product of his craft as perfect, for he knows that pertection in human affairs, more especially in mechanical matters, is non-existent.
If, at times, we cannot see far enough ahead to -discern the opportunity for further. improvements in this or that direction, it does not, by any means, follow that we should, therefore, be content with what we have, for that way lies retrogression and decay. The Chinese' afford us an excellent example of a nation afflicted with this kind of "laissez faire" outlook upon life, and, as a result, all their mechanical contrivances, and they are not numerous, are in about the same state of perfection, or lack of it, as they were a thousand years ago.
Let it be understood, however, that it is not intended to imply that "The Inspector's" views are as antediluvian as those of the Chinese, and the writer hopes that he will not be rashly accused of any such doubtful insinuation. It is merely his wish to point a moral as to the ultimate results to which the too easy acceptance of the doctrine qf "no improvements needed may lead.
If we are not sufficiently gifted with the prophetic vision to foresee ultimate developments, we -can, at least, patiently forge ahead improving little by little, for it is by this means that all great mechanical achievements have been brought about.
Having indulged in some more or less negative criticism of the theory put forward by "The Inspector," the writer feels that his remarks may be more convincing if he attempt to tread the dangerous ground of prophecy and endeavour to give some rough idea as to what kind of motor lorry we may expect to have offered us by our enterprising' manufacturers in, say, 10 or 15 years from now_, when we may hope to have advanced a stage further on the road to perfection.
Generally, we look for the elimination of all but essential features in the way of working parts ; in other words, we may expect to see mechanical transmission eliminated, and, in its place, probably an hydraulic or electric system. Probability rather points, in the writer's opinion, to the former owing to the fact that it offers the possibility of applying the motive power directly to the road wheels, whereas an electrical system requires, so far as one can see at. present, a geared rear axle similar to that now used on the Stevens petrol-electric lorry, which is. in fact, identical with the ordinary type of worm-driven axle.
Another advantage of the hydraulic transnah sion lies in the fact that all working parts are selflubricating, since oil is, of course. the fluid medium. used. Again, that necessary evil the differential gear; would not be needed. owing fusee power being delivered to each driving wheel nide endently.
Of course, it is well known that one or -two trials have already been made in this direction. but they have not, as yet, resulted in a sufficient degree of efficiency being obtained to enable commercial production to be possible. Further improvement is merely a question of time, and the advantages of the system as such, both actual and potential, will scarcely be denied.
If any reader n doubtful on this point, he is recommended, -when opportunity offers, to visit any dock where large steamships may be seen unloading. Some will 'certainly be found fitted with hydraulic cranes, others with the old style steam winch. Comparison in this case will certainly be odious, the silent power of the one and the noisy rattle of the other being immediately evident..
With regard to the power unit, the most vital and important item in any self-contained motor vehicle, prophecy is a little difficult, but the writer will venture the opinion that some kind of rotary internalcombustion engine, analogo-us to the steam turbine, will eventually be developed ; not the type of rotary engine with which we are familiar in aeroplane work, but one which does not involve the use of reciprocating pistons and valves with the attendant vibration and multiplicity of wearing parts. Many inventoes are at work on this problem, and we live in hope of their efforts being attended with early success. The above suggestions are based on the assumption, not by any means necessarily correct, that the propulsive energy will continue to be derived from some variety of liquid fuel consumed in an internal-combustion engine of some sort. Our ideas on this subject also may, of course, need to be revised at any time by reason ofthe discovery of some entirely different means of generating power. Concurrently, with the above-mentioned changes, we may look for a greatly increased simplicity of control. That nightmare of budding drivers, the change speed gear, will, of course, disappear along with the out-of-date gearbox, and in its place we should have a system which allows of control by means of a single lever governing the speed of the vehicle, the engine, meanwhile, having its speed and throttle opening automatically controlled to suit the load at any particular moment. In -other words, we should have a control as simple 'as that of the electric tramcar plus the necessary steering gear. This latter must always be improved in the direction of reducing to a minimum the effort required to operate it. On somedesigns, this desideratum is already practically accomplished. With regard to wheels and tyres we already possess frictionless Ithler bearings, and tentative experiments with large pneumatic tyres should be carefully watched, for they indicate the probable line of development. The solid rubber tyre is, at best, but a makeshift device.
The present type of leaf spring is, likewise, not by any means ideal, and we may expect to see this arrangement superseded in the future by hydraulic or pneumatic suspension. • We must not forget, also, that along with improvements in the vehicle itself, the art of road construction will, undoubtedly, be developed on the lines of a, smoother and more durable surface.
Already, in America (until recently very backward in this respect) hundreds of miles of ooncrete roads have been built. This form of construction seems to be the keynote of future progress in road construction, as it possesses, in a high degree, those elements of strength and durability which are absolutely necessary in view of the enormously increased use of heavy motor vehicles which is already in sight.
Lela AXLE.