MAKERS BUSY

Sun (Auckland), Volume IV, Issue 1030, 22 July 1930, Page 6

MAKERS BUSY

NEW SILENT GEARBOXESBEING EVOLVED With a continual improvement in top-gear performance of motorcars, a new class of transmission system has been emerging in which a successful endeavour is made to overcome the two disabilities that have so long been prominent features of the orthodox gearbox, namely, noise and difficulty in handling. New gearboxes, in which one or more of the indirect gears is very nearly as silent as the direct top gear, are now standardised on several cars; the figures being five British, four Continental and -seven American. The difficulty which most people experience in changing gear at anything but low speeds, together with the noise produced by the gearbox on indirect drives, have been rightly regarded as a drawback. Consequently a determined effort has been made during the past few years to overcome these disabilities without losing the essentia! features of efficiency arid longevity To a very great extent the silent third or “twin-top” gearboxes, which are a feature of such a number of 1930 cars, meet the requirements which have been stated. Furthermore, the fact that a silent third-speed ratio is available, and can easily be employed by a simple movement of the gear lever, has enabled designers to use a higher top-gear ratio than is otherwise considered desirable. The argument is that as the “silent third” can be fully employed for acceleration and the climbing of severe hills, the top-gear ratio may well be made higher so as to cut down the rate of engine revolutions when the car is running at fairly high speeds on a main road. This not onlv reduces the wear and tear on the engine, but also makes a car more pleasant to drive. It is claimed that a “silent third” gearbox might permit an alteration in top-gear ratio from 5£ to 1 to to 1, and this would achieve a reduction in engine speed of from 3,000 r.p.m. to about 2,400 r.p.m., which must result in a considerable reduction in the petrol consumption.