MOTORING

Press, Volume LXIX, Issue 20789, 24 February 1933, Page 7

MOTORING

ENSURING SAFETY. THE ANNUAL OVERHAUL. NEED FOR ADJUSTMENTS. Many old motor-cars on New Zealand roads arc endangering the lives, not only of those in them,, but of everyone who passes them. Especially in the holiday season, when roads are crowded, anyone who drives an inefficient car is at least a nuisance, if not a menace, to other users of tho roads. The simplest and most effective insurance for motor-vehicles is preventive maintenance through periodic inspections. Such inspection will catch trouble before it happens by uncovering the need for adjustments or repairs at a time when they can be made easily. : Carried through to their logical conclusion, regular inspections represent an actual investment, because they lower the final cost of ownership by maintaining the performance, comfort, and appearance as well,.as the safety of a car at a high level. Old Vehicles Scrapped. The modern automobile is as safe as it is possible to make it when it leaven tho manufacturer's plant. Brakes uri more powerful, more efficient, and easier to maintain. Headlights are scientifically designed tp illuminate tho highway without blinding on-coming drivers. Steering mechanism' is bettor, .tyres are sturdier, horns are more dependable, and windshield wipers and rear vision mirrors are standard equipment on all models. Car manufacturers have gone even further in their efforts to do their share in safety maitnenancc. Tn America last year they voluntarily scrapped 360,000 vehicles which were deemed to have served their time and were considered no longer capable of being maintained in a safe operating condition. Such cars formerly were re-sold at whatever price they would bring, and added materially to the hazards of driving. Compulsory Inspection. The industry has developed and spread widely equipment which makes inspection and servicing of a vehicle's safety factors a simple and convenient process. Inspection at least once a year is compulsory in a number of American States, while largo numbers of municipalities are conducting safety inspection campaigns which make it easy for the motorist to learn the true condition of his car. jpven whero such campaigns have not been officially conducted the facilities are available for thorough safety inspections at regular intervals. No piece of machinory, no matter how well it is constructed, can be operated continuously without becoming worn or without getting out of adjustment. Motor-vehicles are no exception. They, too, demand proper maintenance if they are to deliver to their owners the fullest return on their investment. Operators of commercial motor-vehicles have recognised this need to a largo extent. They subject their buses, or trucks, or passenger cars to regular inspections, not only to make sure that all chances for accidents are eliminated, but also to reduce operating costs and to hold down depreciation. MOTOR CHASE. POLICE OFFICERS ACCOUNT. For the first time (outside numerous works of fiction dealing incidentally with such incidents) a police officer has given to the public, through Iris evidence at a Polico Court, a plain and lucid account of a motor chase with minute details of the manoeuvres, states tho "Weekly Scotsman." While patrolling Uxbridge road in a police car with two other officers a touring car containing four men passed west. He drew level and saw some cartons of cigarettes in the back of the car. (For brevity, we may call the police car A, and tho other car B.) B, ''noticing we were interested in him," increased speed and edged out towards A, while* A tried to edge him towards his own side of tho road. B, being challenged fey whistle and otherwise, refused to stop. Going thus they overtook a heavy lorry. B, being thus blocked, turned towards A, struck his front vneel, and forced him over in front of an oncoming car. This wa3 a point to B, for A had to brake suddenly to avoid collision and B went ahead. Continuing tho chase, A had to swerve sharply twice to avoid missiles thrown at his windscreen.. One of these missiles was the rear seat of B's car. A then twice charged B's ear from behind, hitting it each time, but failing to stop it, and the pursuit continued. It ended when A executed the daring manoeuvre of striking B's offside wheel with his own nearside wheel, forcing B on to the footway, where B's car overturned. The four occupants were arrested. Three were remanded in custody and the fourth had to go to hospital. /The London bus driver is said to be the most skilful of all motor drivers. But even he has not to take any of the chances entailed by a nicely calculated collision at high speed,, as this police driver did. REDUCED TAXES. EFFECT ON MOTOR INDUSTRY IN DANZIG. In the Danzig Free State the motor industry was becoming retrograde; high taxes and appalling economic conditions bad their influence on : the number of registrations, which were steadily declining. That was the position at the commencement of this year. The Danzig Government decided to take radical stops to remedy this situation, and at the beginning of April the horsc-powcr tax was lowered on commercial vehicles by 25 per cent, and on private cars bv 50 per cent. At onco the industry revivod. Itoevntly official records became available Private cars showed an ama«ia:» increase, tho number of registrations having grown by more than '-0 per cent. Jn the case of commercial vehicles the success oi' the new measure has not been so marked, owinj; to tr:;dc loss by reason of the recent diversion of Polish slapping to the port of Gnydia. The increase, however, is 15 per cent., which, iu tho circumstances, is very creditable. Have you anything t'o sell—Do you wish to buy? It so a small advertisement in the classified section of Th» Press will be all you need. 12 words Is, three insertions 2s 6d. <—<>

BY «ROADSTER."

LOW BODIES. STABILITY AND CLEARANCE AN AID TO SAFETY. The layman is sometimes inclined to think that tho new low bodies which have replaced the high ungraceful structures of a few years ago have been achieved at the expense of ground clearance. This is not, however, the case. The effective ground clearance of any ear is the distance between the lowest point of the chassis and the road. It is no use perching a body high up in tho air on steeply cambered springs if the front and rear axles have only 8 or 9 inches clearance, and yet that is what was happening in the past. Today, while ground clearances aro substantially tho same as tticy were, body height has been by s>x or eight inches, and in some cast' 3 even more. What has influenced this trend, and how has it been carried out with no sacrifice in road clearance? The answer to the first of these qucrios is simple, and can be summed up in tho word "safety." The high average touring speed of which the modern car is capable has made u necessary to build a chassis possessing a degree of stability hitherto considered unnecessary. Take the present-day edition of any popular car you may happen to know, and imagine the engine fitted to its namesake Of seven or eight years ago. What would be the use of the power, the acceleration, and the high-speed, silent, intermediate gears, if we had to travel at an average speed of 20 to 23 miles an hour in order to avoid the risk of overturning on corners or shooting off the road altogether on really broken surfaces? Tho absolute essential of fast, safe motoring is a low ccntro of gravity and this has been achieved, strangely enough without detracting from the effective road clearance. The centre of gravity is the point at which the weight of tho car is taken to be concentrated. This point is calculated mathematically, and its height from the ground determines the stability of the car on curves and corners, its liability to skid on wet surfaces, and tho directional control afforded to tho steering gear. Skidding, and the tendency of a car to lean outwards on corners is simply tho effect of centrifugal force acting in an outward direction upon the centre of gravity of tho car. It is obvious therefore "that tho higher the body, and consequently the centre of gravity, the greater will be the leverage exerted by centrifugal force and the greater the risk of overturning or skidding. A high body naturally gives rise to a great deal of sway, and also accentuates tho action of the springs over rough road surfaces. Tho lower body therefore, in addition to its safety features, also contributes very largely to comfort. Wind Resistance. Jticardo, the famous designer and consultant, once mado a remark to tho effect that a machine to be right must look right, and this simple statement it will bo found holds good in all branches of engineering. Even.tie layman has an inherent feeling that for speed and safety a car must look low and compact. That is why, apart from anything else, the new cars possess a degree of grace aud beauty which gives one a' feeling, of confidence in tho essential soundness of their general design. Tho present low bodies, possessing as they do a greatly reduced frontal area and smoother, more flowing lines, contribute very largely to the elimination of unnecessary wind resistance. The .reduction in overall height of the modern car has been attained by dropping the chassis frame between tho axles. The height of the front and rear axles is the factor determining ground clearance, so that by dropping the height of the chassis frame "between the axles, tho body can be set well down within the whcelbase without reducing in any way tbo essential clearance between the car and the ground. In order to bring about this alteration, ideas as regards springing have had to undergo a considerable change. The old conception of a spring was that it'should be a steeply curved affair, with the ends a considerable height above the centre. Designers have now shown, however, that this steep camber is quite unnecessary. and that flat springs, or even springs with a reverse cambor, are equally effective from the point of view of shock absorbing, and very much more stable at -high speeds. So that, if the owner of a modern car notices that when loaded the ends jof his springs are lower than the centre, or, shortly, that his springs have assumed a reverse camber, he need entertain no fears regarding «oft springs or other "horrible imaginings." For 1933 some British car makers have gone even further than the double drop frame, and have slung the frame under the rear axle instead of over it. This procedure is a complete reversal of previous passenger car practice, and its success proves that a spring can •perform its useful functions whether it is flat or curved, or whether it is carrying its load in suspension or compression. BACKFIRING. . NO NEED FOR ALARM. Alarm is sometimes experienced by those who are driving their first car. to find that when taking their foot off the accelerator pedal, whije driving aloug a level road, and especially downhill, to hear a series of loud explosions oecur in the muffler, known as backfiring; and there are probably very lew car owners who really know the cause, aud may imagine that their engine is badly out of tune. Backfiring iu the muffler is likely to occur ou any car when the foot is suddenly removed from the accelerator pedal or when coasting, so that the car is "pushing" the engiue. Theoretically, what happens is this: The sudden closing ot the throttle results in a very high vacuum in the , intake manifold. This excess vacuum ; interferes with the incoming charge, producing an over-rich mixture which is not completely burned, and is consequently pumped into the exhaust mauifold and muffler along with tlie exhaust gases. The heat iu the muffler then vaporises this over-rich accumulation, and when it reaches the proper state, it is exploded by other charges from the exhaust manifold. This produces the backfiring noises iu the muffler. If these explosions occur too frequently, it-might be well, of course, to have the carburettor inspected, as cases -have been known where tho needle valve is worn and an over-rich mixture has resulted, leading to imperfect carburatiori.