"TWIN-TOP" GEARS.

New Zealand Herald, Volume LXVII, Issue 20596, 21 June 1930, Page 38 (Supplement)

"TWIN-TOP" GEARS.

BILENT THIRD SPEED. * . With a continual improvement in top-gear performance of' automobiles, a a new class Of transmission system .has been emerging in which a successful endeavour is made to overcome the two disabilities that havo' so long been prominent features of the orthodox gearbox, noise arid difficulty in handling. New gearboxes, in which one or more of tho indiiect gears is very nearly as silent as tho direct top gear, aro now standardised on several cars now on tho market, the figures being five British, four Continental and SQven 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, havo been rightly regarded as a drawback. Consequently a determined effort has been made during the past few years to overcome these disabilities without losing tho essential features, of efficiency and longevity. To a very great extent the silent third or '"twin-top" gearboxes, which ore 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 tho gear lever, has enabled designers, to use r 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 at fairly high speeds on a main road. This not only 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 altration in top-gear ratio froip 5£ to 1 to 41 to 1, and this would achieve a reduction in engine speed of from 3000 r.p.m. to about 2400 r.p.m., which must result in a considerable reduction in tho petrol consumption. PARKING IN THE CITY. A pound an hour appears to bo the standard rate at an English Police Court, for cars left beyond tho time limit in city car parks, according to. an English journal.. This exhorbitant. charge is intended, cf courso, to discourage excessive parking. The writer suggests that what the motorist who parks in the city really needs is a car which will change its ap!iearance automatically after a certain apse of*, time. It is to be hoped that the' decision of tho Auckland City Council 'to prohibit all-day parking in the city, as from the beginning, of next year, will not result in • such drastic penalties being inflicted on any offenders. PETROL SUBSTITUTES. Two substitutes for petrol as-a. motor': fuel are being studied, one-in Switzerland and one by the United States Bureau ?;df Mines. The Swiss fuel is called and is manufactured from .wood charcoal. This would be used chiefly for the operation of ' trucks. It; is said to show an economy of 70 per cent, in operation. The AmericJ.n fuel is petrol made from- shale oiL Refined shale oil gasoline under ; test .developed more than 4 per cent, electrical horsei)ow i er more than the ordinary petrol. * % ." ■ ■' - ' •' ■ . • x : . NEW- AMERICAN RECORD. It" has been announced by the Florida; representative of the American' Automobile Association, after a comparison of the official records'/ with the speeds Kayo Don Attained during his 22 trial; runs,: that a new American straightaway record of; 151.623 m.p.h, for' five miles has been set'up. The-previoua record was made' in 1920 by Tommy s Milton, -who averaged : 149.5 m .p.h., when driving • a 12-cylindcr : Duesenberg. •_ *.'• , *■ - , THE LATE COUNT BRILLI PER]!. Motorists have learned with regret of the death of Count Gagtono Brilli Peri, ■who was killed in Tripoli when, practising for the Tripoli Grand Prix. An amateur, Brilli Peri was a brilliant driver and a ■very. popular figureMn the. Continental' racing world. Most of his successes were associated with Alfa-Romeo cars, but he met his death when driving a 1500 c.c. Talbot, which was the identical car in which he won the Tripoli "Grand Piix last year. Brilli Peri won the Grand Prix of Italy at'Morizaiii 1925 with ah Alfa-Romeo; in''l926,' 1928 and 1929 -he ■was second in the Grand Prix of Rome; ' in 1928 he' waii fourth in the' Grand Prix of the Nations > at- the- Nurburg Ring; last year 'he won the ' Grand Prix 'du Mugello and ih'e Grand Prix of. Tunis, The lCLkilometre International Class D record also stood to his credit at 138.77 m.p.h. USE OF AIR FILTERS. It may not bo generally known among motorists that aluminium pistons wear the cylinders more than cast yon. pistons if.: the air to the carburettor ( is ipot efficiently filtered. This is because the soft aluminium holds the minute particles of grit drawn in through the carburettor in its soft surface, and these, wear and score the cylinder wall as the piston moves up I and down. So much is this' so that a email, high-speed engine has been known to be reduced in power efficiency, by. 25 per cent., in a matter of ten. thousand miles. The piston had worn the cylinders Bo that there was practically no. com-, pression. If this state of things has been allowed to. develop the only remedy is to yebore the cylinders and fit entirely new pistons c f the correct new size. The trouble of worn cylinders can be avoided by proper attention to the lubrication from the start of using the car, and by fitting to the carburettor an efficient air .cleaner or filter. With an air filter, which is cleared at fairly frequent intervals, and good lubrication carefully 'filtered and frequently renewed, piston -'wear should not arise until very great mileages have been covered. The buyer of-a-car which is not fitted with an air cleaner should have one fitted. It can bo done easily and the cost' is small, compared with tho money_ for renewals and tho disappointment in performance which it will save.