FRONT WHEEL DRIVE

New Zealand Herald, Volume LXVI, Issue 20372, 28 September 1929, Page 14 (Supplement)

FRONT WHEEL DRIVE

A COMING DEVELOPMENT. Front,' '-wheel drives have passed the oxperirricntajstage, mid following tho British tftdJ .Continental lead, an American firm / produced a standardised closed with <tho drive by tho front axles. Otic oF-these interesting vehicles will in .Auckland shortly. Thero are fndjfitioM that front wheel drive is tm tho';fhcrCaso and some experts even predict /tEjat it will eventually become as populates- front -wheel braking. Fronts wheel transmissions «iro by no rneyns hew. It is interesting to observe that it 'isi-tho fruit of racing experience, as far aro concerned, although, , drive by totli front and back wheels has been used in American and British commercial Vehicles to a limited extent. Auckland motorists will recall a demonstration given in Auckland some years ago with an Ainericai^'four-wheel drive truck, which climbed remarkable grades. With commercial vehicles front wheol drive has been applied in conjunction with normal rear drive to give better traction on steep or unmetalled roads. Jt. is a different object that has actuated designers of front wheel drive cars, and tho change does rot necessitate the retention of back axle transmission. The interesting examples of front wheel drive cars now available for tho ordinary motorist are tho Alvis (British), Cord '(American), Tracta (French), and Selve Select a (German). Twenty-two years ago, a front wheel 'drive car was built for racing in tho United States, and tho system was very highly developed in tho American Miller cars, which are now so conspicuous on tho board tracks in tho United States. It is in fact, remarkable that tho front axle transmission was applied to both British and Continental production models before an American example made its appearance. %

Front wheol drive permits a great reduction in body height, and the car can be built to hug tho road. The rear axle is the limiting factor in reducing the height of a car. With front wheel drive, a livo rear axlo is unnecessary, and the unwieldy bulgo is eliminated. The wheels havo to do nothing* more than carry tho load, and it is not really necessary to carry an axlo across tho car. At least two makers havo stub rear axles. Body builders havo naturally great latitude with front drive chassis. It gives them a platform entirely free of mechanism. In one eight-cylinder sedan with a large comfortable body, front wheel drivo has brought the highest point of the body down to 61 inches, still leaving 38 inches of headroom. Although so low-built, the car j retains the clearance of most rear drive cars.

Fast cornering was tho characteristic of front wheel drive, which led to its application to racing. It was seen that there were advantages in pulling instead of pushing a car around bends. In fast driving on tho open road, tho usual method of taking a bend is to coast into it as fast as safety allows, and apply tho power just as tho car is coming out. .With front drivo, tho procedure is different. A steady speed is chosen, and tho power is kept on the whole timo. This is not altogether a virhie, as it might lead to rathoi fast cornering in ordinary driving. Front drive enables suspension improvements by reducing tho unsprung weight and replacing tho long drivo shaft with a very short shaft. Even tho brake drums ' nded "not bo mounted on the front wheels with this form of transmission, somo makers having placed this gear on tho short drivo shafts. Tho wheels, therefore, are very light, and tho brako .equipment is sprung weight. A disadvantage of front drivo is that the weight on tho front wheels may not bo sufficient to give a good wheel grip in, wel conditions. Wheel slip naturally interferes with steering, and is accordingly more serious than-slip with rear drive. In the French Tract a, the front wheels are independently sprung-' by cylindrical tubes, containing' coil springs, .which function quite freely while tho ' drive is taking place. The brake drums y aro close to tho differential, which is placed low down in front of the radiator. A four-cylinder 12h.p. engine is installed and the saloon is just over five feet in height. f ' BPRAGS REVIVED. Many • years ago cautious motorists v would "have welcomed a spragging device which would have prevented the car running backwards on a hill. A number of spraga wero patented in tho early days ■ of motoring, but they were all clumsy and unpractical. Even in Now Zealand application was mado for a jamming device.; Optimistic inventors have actually ■evolved fittings designed to trip and spike tho ground. All theso early devices caused trouble when normal reversing was dernfed. '

Sprags located behind tho gear-box have now been standardised on two of the highest quality cars produced in America, and substantial firm 3 directs attention" To recent forms of tho apparatus. ,In America sprags aro known as " no-backs." They aro intended for the driver who gets into, troublo when stopping or starting on a hill. The test is to run up a hill and slip tho gear-lever into neutral, allowing tho car to coast to rest. Tho car simply rolls to a stop, and thf!n takes up tho back-lash in its transmission, and stops immovable against its spiag. No .brakes aro necessary. To start off, low gear is'engaged and tho clutch operated for a smooth pick-up without any recourse to tho brakes. Should tho engine bo stalled in takingoff, tho car would simply slip back on its sprag again, even on a grade of 1 in 3j. When it is actually desired to roverso with tho engine, tho action of slipping the lever into engagement, automatically puts -the sprag out of action, so long as tho gpar is engaged. Tho apparatus has thus ho serious faults and it certainly allows great driving ease in traffic. One is never troubled hy tho tendency to roll back while waiting for tho traffic signal. Tho device which has been put into production in America embodies a roller and wedge which cause gripping action on a drum.' Any backward movement causes tho roller to jam, Tho inter-connecting of tho gear-lever operates a stop device to pormif intentional reversing. Several are on tho market in England as extras. Ono can bo. fitted to certain cars for/about £lO. A sprag could probably bo fitted for about £1 if incorporated in a car as a standard, and built in behind tho gipar-box at tho factory.