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YOUR OPINION
Page 113
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:sign Progress ?
OUR recent road test report of a mass-produced 7-ton truck (Morris FJ, August 6) left me wondering just much progress has been made in vehicle performance ing the past 10-15 years, particularly in this class. Jsing past road tests of The Commercial Motor as a le for the vehicles in the 5and 7-ton capacities, nd the figures of considerable interest. The two accomying graphs have been drawn up using averages for icle performance.
'he most significant fact shown, in both the 5and 7-ton es is the steady increase in the unladen chassis weights, ticularly in the latter class. No doubt that can be punted for by the more general use of heavier transsion components such as 5-speed and overdrive gear:es. 2-speed axles, and so on. The use of these wonents, however, has reduced the vehicle acceleration es from 0-30 m.p.h. by about 30 per cent for the inners and as much as 50 per cent for the 7-tonners. wever, in view of the more modern materials and techties being employed, one would have thought that the aden weight could have been kept down.
'he power/weight ratios increased appreciably in the 1950's and have remained fairly stable since, but le of the current 5-ton vehicles are showing a decline their power/weight ratios, no doubt because of the tinually increasing chassis weights, and this despite the id towards larger and more powerful engines.
,aden fuel consumption is about 10 per cent worse on rent 5-tonners, but it has remained fairly constant over years on 7-tonners. From the safety angle, braking ances have been reduced on both classes of vehicle— re drastically on 5-tonners, where a 33 per cent reduei has been obtained, compared with the 15 per cent uction for the 7-ton vehicles. It can only be concluded m this that more effort have gone into speeding up 7-ton class than in trying to brake it more safely.
'inally, according to the performance figures of today's idles, it would appear that we have faster but safer idles than a decade ago, at the expense of m.p.g.
lirmingbain, 10. N. J. PAINTING, lirmingbain, 10. N. J. PAINTING,
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