WEIGHT AND RATIO

Wanganui Chronicle, Volume 73, Issue 370, 13 September 1930, Page 21 (Supplement)

WEIGHT AND RATIO

It is an axiom that other things being equal, the lighter thc weight of the car the more economical will it be from thc point of view of fuel consumption. There have been c..rs w.th good engines spoilt because thc load of body and chassis has been too great to permit thc car to have a good road performance. The matter of thc gear ratio between engine and road wheels is also of very great importance. It would be easy to take an engine developing 30 h.p. at 3000 r.p.m. and so gear it in a ?ar that thc ratio and weight would entirely prevent the engine getting any chance of rotating at its 3000 r.p.m. Therefore, it could not develop its 30 h.p. and it would be slow by reason either of too small a back axle ratio or too much weight of chassis and body. It is an easy matter to alter the gearing—and it is often done—to accommodate a heavier body load. But if the ratio were made lower to suit, an increased load thc road speed at any given rate of engine revolution would obviously be re ;/ed.

This consideration points to the importance of keeping weight down and since the car has lo carry thc engine, chassis, and bodywork, as well as the weight of the pi.ssengers. it is of thc utmost importance to eliminate every ounce of superfluous weight in its construction. It is only in this way that the best performance and economy from any particular engine can be obtained. The use of metals ot light-weight becomes then essential in motor car construction; and then, again, in order to get thc highest effective speed from thc engine, the designers have found the absolute necessity of reducing the weight of reciprocating parts. This has little to do with thc total weight of thc vehicle, but owing to the effect of inertia, it both increases power losses from friction, and limits the speed at which the engine will rotate. It is thc main factor in limiting power output and to reduce it has been the aim of engine designers for many years past. It will be admitted that in this they have achieved remarkably good results when wo <>ompare the engines of to-day with those of 10 or 12 years ago.