Air, from Tyres to Suspension
Page 42
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THERE are not wanting road transport operators and engineers who are inclined to believe that the development of air suspension for motor vehicles is only secondary in importance to that of the pneumatic tyre. There is, of course, a curious similarity between the two, in that some forms of air suspension are closely akin to tyres in their construction and the value of air for the purpose of supporting heavy loads has been well proved. There is the added advantage that pressure at each point of support can be made to balance the loading there, so that the stability of the vehicle as a whole can be definitely improved.
In view of the advantages claimed it seems curious that so little has apparently been done in the past to make use of air in this new way. But once started, progress has proceeded apace. Moreover, such systems of suspension should be lighter than the conventional methods, although perhaps the saving may not be so great as might be assumed, for the reason that air, unlike a laminated spring, cannot in itself perform the dual functions of taking braking and other stresses and must therefore be provided with restraining media to give locational strength. It was these combined attributes that have given the laminatee spring such a long run as a main constituent of motor vehicles of almost every type. Incidentally, it acts largely as a damping device, resulting from the friction between the sliding leaves, but it is not capable, in general, of dealing satisfactorily with minor vibrations, which normally are transmitted to the chassis without any real damping effect. Consequently, shock absorbers or ancillary forms of spring are usually employed.
It may be too early to wax excessively enthusiastic over air suspension, despite its early successes. It will pr9bably require experience over a period of years to permit arriving at a definite decision as to how great an advance it may be.
That appears to be the way in which air suspension is being viewed at present. If it shows itself to be a great success it may exert a strong influence upon the future of vehicle design. It is quite likely that it may become possible considerably to reduce the weight of both chassis and bodies, as a result of the cutting down of vibration and racking stresses, whilst the life of vehicles specially designed for this form of suspension should be much enhanced.