MODERN MOTORING.

Auckland Star, Volume LVI, Issue 189, 12 August 1925, Page 12

MODERN MOTORING.

THE GENEALOGY OP BRAKES. The department of public safety In New York and several othc? American cities have flying squadrons,' whose chief duty ie to stop unsuspecting motorists, appropriate the isiheel, and proceed forthwith to test the brakes. In one month recently 1000 brakes trere co treated, and something more than 700 owners were requested to fix the brakes or see the judge, or both. Signs of the times! The handwriting is on the wall, to say nothing of the police blotter. It behoves you and mc, Mr. Lay Mann, to investigate the •übject of brakes before a traffic " cop " brake-specialist does it for us, says the Sydney "Telegraph." Mr. Pre Historic, when driving his Dinosaur Six, found that it slid down hill faster than it ran on the level. It took work to make the grade, but when he reached the top that energy was stored up, and as he made descent, it was manifested in increased speed, sometimes so much so that he felt need of something to break the force. Accordingly, he hitched a rawhide around a rock and heaved it over at the top of the hill. Result: the rock just balanced the extra force, and he rolled to his cave with dignity. Being of an inventive mind, he soon tired of carrying the extra load, and found that a stick pegged on the side of his cart would accomplish the same result. And there is the whole story in a hub-cap. When Mr. Earl E. Roman perfected the Clubby Chariot, he found that he had greater speed and could carry bigger loads than his predecessor. This brought the necessity for better means of stopping. Simple methods of leverRges came into play. He used a stick, ■which was pressed against the wheel. As the time passed, the two-horee power chariot gave way to the four, and then more pressure became necessary. To do this double leverages were invented, and linkages came into being. " Linkages n are nothing more than sets of levers hitched up together. To-day it is not uncommon for the linkages to give a mechanical advantage of 30 to 1. This new power developed by the linkages brought additional trouble for a time. The wooden lever and wheel did not possess sufficient lasting qualities. When applied for some time, with the vehicle moving at high speed, our friend, J. Caesar, was humiliated to find that his brakes were on fire, and he skidded across all Gaul. Then came a big discovery. In bringing a moving object to rest the motion is converted into heat. Therefore, some substances that will stand high temperature are necessary for a ■ braking medium. The next stop was metal to metal. This served for many years on passenger vehicles, and is still found on a few. Many combinations were tried, with the hope of durability and quietness; iron on steel, bronze on steel, steel-on steel. These experiments resulted in bringing forth the knowledge that the less wear in a given time the better are the brakes and lining. To-day the metal to metal brake is rapidly becoming extinct for automobile purposes. The chief objections are noise, and the difficulty and expense attendant on repairs, the cost of metal blocks being excessive. Early substitute materials used as brake linings included leather, camels' hair, jute, and cotton. All lacked the necessary qualities to stand up under the tremendous heat developed by John D. Friction and our forefathers had to "squeak" along as best they could with the metallic brake. Early in this century a lining was produced from that queen of minerals—asbestos. With true femininity ,it was cold to heated, advances .of steel, yet possessed sufficient temper to cling when the victim was slipping. And co is written the genealogy of brakes, the three essentials being ample co-efficient of friction, slow wearing factor, and a reasonable cost. Look well, then, to this, the most important part of your car. A tree or stone wall will effectively stop a car, but in the process the driver, his passengers, radiator, mud-guards and other equipment usually are injured. Motorists! You should know that your linkages, toggle joints, lining, etc., are in perfect working condition. Then when some inquisitive traffic policeman a tops you, you can say: " Yes officer, I have a perfect braking system of the external contracting type. With a mechanical advantage of 30 to 1. properly adjusted bands, and a lining of the highest quality, I have an ample co-efficient of friction of point forty." Seriously, however, there is no doubt but that of the hundreds of motor fatalities that take place every year, many may be traced to. defective brakes. It is astounding to think that to-day there are probably thousands of cars in this country that have control apparatus that is in need of adjustment. Even without legislation there is no excuse for any motor owner to endanger his or her passengers' lives, or those of the public, by driving with unsafe brakes. It is a very simple matter for anyone to test them. Assuming that, your speedometer., is reasonably accurate, drive your car on a quiet piece of level country road, at various speeds as below, and when passing a certain fixed spot or landmark, such as a telegraph post, milestone, gate post, etc., apply in turn each brake. As soon as the car has stopped, measure the distance back to the spot where the brake was first applied. See how.your distances correspond with those given in the following table:— * Table showing distances in which a car travelling at various speeds should be are U |fflclcnt a stnndstin lf tlie brakes used v.t . „* Dietance in which car should Car speede be pulled ud In miles With two-wheel with four}er hour. brakes. wheel brakes. 10 9-3 ft. c f t 15 21 ft. 13 sft 20 37.5 ft. 24 ft' 0 84 ft. R.i f t 35 114 ft. 735 If--40 100 ft. ni° \\- -50 232.4 ft. 106 ft. If your figures do not come up to these, you should lose no time in having your brakes attended to if you are unable to adjust them yourself.