THE SIX-WHEELED VEHICLE

Evening Post, Volume CIX, Issue 148, 26 June 1925, Page 15

THE SIX-WHEELED VEHICLE

So great is the reduction on road -.wear by six-wheeled heavy tonnage motor trucks that the question arises: Will this type of vehicle eventually by legislation be the only heavyweight automobile permitted to use.the highways? The road .engineers of every civilised country' in the world aro greatly exercised in. their minds at the vast increase in the volume of motor traffic and the consequent extra wear both on surfacings and foundations. It is being realised on every hand that the science of road construction is not advancing at anything like "the same speed as the growth in road usage, and that the cost of building and upkeep—always great—is likely to reach critical limits unless something be done to alleviate the situation. It will soon be necessary either to build roads which will possess a greater potential life, or to reduce the factor of road wear per vehicle.; As "matters stand., it would appear that road foundations (even in Europe and America, where scientific road construction is more advanced) have almost readied the limit of their development, so far as the materials employed and their actual construction are concerned, am! it is. therefore, most essential Mutt careful attention be given to the second method.of solving the problem. It may be done partially Ijv the more extensive employment of pneumatic tires, even on the -heavier classes of vehicle, but still more is lo be said for multi-wheel construction. ■ Experiments conducted by the U.S.A. Government have; deninn^tratcd that v 5-ton -lr-.-nl can l.c carried .as far on one sit of |)"i)eiiiinitiuj on ssi.v wheels' (Lun '-suit ajid foui' ftt yejy of. yeUid^L s$ pij

two complete sets —eight tires—on a four-wheeled truck. As this means a 25 per cent, reduction in tire wear and as tire wear bears a certain ratio to road wear, this factor alone is important. Then, as to impact, it has already been mentioned that a 2-ton 4-wheeled truck, shod with solids, with a 2-ton load \rp, gave in a test an impact figure of 21,9001b. With pneumatic tires fitted in place of the solids, the impact was reduced to 73001b. Again a 5-ton 4-wheel-er, fitted with twin solids at rear, and loaded up to five tons, gave the high impact figure of 29,0001b. Fitted with pneumatics and six tons up, the figures were reduced to 11,900. This is a remarkable reduction, but nothing to what happened when a six-wheeler, carrying a load of 8J tons, was put to the test. The impact figures fell to 70001b, or 3001b less than the pneumatic shod 2-ton truck, with less than a quarter of the leading up. What a difference reduction in impact would make'to road wear, which after all is not so much a question of vehicle weight as of spreading the load at point of road contact. ' There certainly appear to ba great potentialities in the development of the six-wheeled automobile for heavy motor truck and motor bus work.