High Speeds Need Sound Braking Units

Sun (Auckland), Volume II, Issue 342, 1 May 1928, Page 7

High Speeds Need Sound Braking Units

How Modern Cars Alee t Traffic Demands The development of the modern car is along the lines of speed, acceleration and rapid deceleration. The light car with the small and highly-efficient engine is the natural result of the attempt to combine these desirable features with small operative costs, and the results are seen in the trend for what we may call the super efficient small car, which will do what only a few years ago, could only be attempted by high-powered and heavy vehicles. Increasing congestion on the roads has called, and is calling more and more, for this “nippy” class of car, with an engine of good accelerative powers and with that advantage has arisen, concomitantly, the very serious necessity for brakes which shall be as efficient and as rapid in their decelerative powers as is the engine in the matter of acceleration. Traffic driving—even on the main arteries between our towns and cities —has become very largely a matter of taking opportunities for passing rapidly and for quick retardation when in emergencies—for emergencies are more numerous and more sudden than they were a verv few years ago. This means that the brake gear of the car should have the same atten-

tion given it—both by the designer and the user —which is given to the propulsive mechanism. The accelerative properties of the engine may be considered almost as a measure of the decelerative properties necessary in the case of brakes. Four-wheel braking has given us the means of rapidly drawing down the speed without great strain upon the tyres, which —as must be recognised—are the sole medium between the car and the road, and which have to take the whole of the retarding and the propulsive effort. The distribution of the braking strain over four wheels, instead of only two, has had the effect of greatly increasing our storming power while not seriously increasing the strain upon the tyres. It has also, incidentally, increased our safety on greasy and slippery and loose surfaces. But with this increased efficiency has come the need for more careful use of the brakes and greater attention to be given to their careful adjustment and keeping in fully efficient operating order. The wise motorist who considers his own and other road users’ safety will make a point of seeing that his brake adjustments are properly made and that braking is equal, under all conditions, on the two wheels of a given axle. The wear of brake linings, in spite of the remarkably good and safe materials now available, must, of necessity, be greater than they were before we had the speeds and traffic which we have today. And town driving imposes a responsibility upon them which* is heavy to-day compared with what it was a very few years ago when the traffic was not so dense. The wise motorist will make the brakes his first care. Their correct functioning is of more serious importance than the correct functioning of the power plant, for inefficent brakes mean danger and perhaps disaster, while an inefficient power plant may only mean speed reduction and delay. “CURING” TYRES FROM BOTH SIDES One of the peculiar things about rubber is the fact that heat passes through it very slowly. For instance, heat passes through steel 200 times faster than it passes through rubber. Because of this fact, when a tyre is cured from outside only, the temperature at the inner side is 28 degrees below the outside temperature, even after 300 degrees of heat have been applied to the outside for more than an hour. When a tyre is cured from the outside only it is a good deal like baking a loaf of bread in an overheated oven. The outside of the leaf quickly becomes done, but the inside, because of its failure to get the same amount of heat as the outside, remains doughy and spongy. With water curing, Goodrich has overcome one of the greatest problems of tyre-making—the problem of securing even distribution of heat all through the tyre. Almost exactly the same heat is applied to the deepest layers of the tyre as at the tread. No part is over-cured. No part is undercured, and thus results a tougher, longer-wearing tread. A powerful bond between the tread, breaker, and plies, and elimination of ply separation! A tyre which is tough clear through! It is reported that Mrs. R. N. Stewart will shortly make further attempts on speed records at Montlhery; she will ride 350 c.c. and 500 c.c. J.A.P.engined machines.