MOTORING

Evening Star, Issue 16624, 5 January 1918, Page 11

MOTORING

/ [By CAKBTJB.ETTOB.] Brief accounts of holiday trips, roads, and places ' of interest are invited for the '' column. MOTOR CAR BRAKES. The distressing accidents and fatalities , that have occurred -throughout the Domii nion during the last few months cause one • to ask wherein lies the danger. Is it due ; to inefficient brakes or to the difficulty of ! changing gear at fairly high speeds, or i partly" to both causes? The ideal brake i would doubtless bo one' which would hold ' a car on any hill that the tyres would : grip, and that wtrold rapidly pull up the car at whatever speed it might be travelling. With two brakes fulfilling these ro- • quirements, a driver need not fear any hill that the wheels wouild grip. : But the best of larakes may get out of adjustment, so that even the two brakes might hardily prove sufficient to hold the car. Yet the careful driver. speedily discovers any lack of grip in liis brakes, and takes other precautions. If the magneto is switched off, and tlio car left in top ; gear, the power required to keep the engine going is -sufficient to act as a gc*>d , brake. Tn second gear fairly 6teep hills > can be negotiated with no brakes on. while in first or bottom gear really stiff declines can be taken. And with the two brakes on as , well, if tbo byakes are in good r order, a car can descend practically any 1 hill that will offer a--gripping surface to '■ the tyres. Where a Bowd-en " extra air " is fitted, the opening of this will still ; further retard the car, more especially in the lower gears, sine© it speedily cools the engine,' and the cosier the engine the stiffer it is to turn. An ideal gear changing would be one which precluded the possibility of missing the gear. Some such gear box may have been devised or may y«t be produced. I [ cannot say. With tho ordinary gear box the difficulty of'changing down or up at high speeds is dire to the fact that two sets of cog wheels revolving at high and different rates of speed, may not mesh. The more nearly tho two or more wheels - are revolving at the same speed, the more easily can they bo meshed. In changing gear, one : of the oog wheels disengaging one wheel has to mesh with another at a different speed. With © car moving slowly, the actual difference in speeds is not as great as when the car is travelling fast, although the relative speeds are the same at all rate 3 tho car travels at. Therein lies one of tho advantages cf changing down early in the deswnt of a steep hill. The other advantage arises from the fact that the car will not travel as fast on a lower gear, and there is less need of the brakes and less chance of them becoming very hot and failing to act efficiently. Naturally, a break iy. any part of the transmission would pi event the engine being used to retard ih-e car, but such breaks Tarely occur when descending hills. Until motor car brakes become so reliable that risk is eliminated, motorists do well to use their lower gejjrs in negotiating steep descents. On all flf our main roads there' are steep hills, -with sharp bends, and these should always be treated with 1 respect. I drop into " second" _ coming down Saddle Hill and Lookout Point, and prefer " bottom" whon Hearing the bends of the North road leading into the Valley. , I may be too cautious, «et I recognise the possibility of the brakes failing on some of our troublesome hills. Man may seem a pigmy by the side of the marvels he has created, yet nothing has been more remarkable in the history of locomotion than the way in- which the human brain and physique have maintained their ascendancy throughout. Pioneer motorists will remember how wonderful it seemed when a motor car ■ first attained a speed of 60 miles an hour. Yet it is now many years since S. F. - Edge v.-ent round the clock at an average ' of sixty-five, although a well-known specialist had declared that the human brain was quite unequal to controlling a ! motor car % at 60 miles &n hour for more 1 than a few minutes at tho outside. It is a good long time, too, since two miles a minute was first accomplished on tho Florida Beach, and ev-jn 100 miles an hour at Brooklands is new an ancient record. Then flying introduced new problems; and when the mastery of-the air was finally obtained the question of high speed arose once more. There are machines -now in existence on which it is possible to attain a flying speed of 145 to 150 miles an hour, and this means that, with a gale behind, the SOO-mile mark may i at times be passed, while dives may even . be brought oft at a speed considerably in excess of that figure. Still the human brain and human physique have proved equal to the demands upon them of pure speed. Now, however, n new factor has arisen. y The aeroplane is not merely fast: , it can climb to heights that were once un- , dreamt of. The exigencies of air-fighting have made it necessary for the field of action to go higher and higher as the war has dragged on, and the machines them- ', selves have been continuously improved t until it is not out of the way for fighting scouts to fly as high as 20,000 ft. But \ alpinists well know that every I,oooft tells where respiration is concerned, and . aviators being able to climb still higher than the loftiest Alp are now finding that in some cases the human factor must needs be reckoned with in a way that has hitherto been unknown. The number of men who can move in comfort at 15,000 ft ' is gradually reduced at each succeeding stage beyond that altitude; and when itcomes to 20,000 ft and over tho machine itself, in some cases, is more efficient than the man. An English pilot was invalided home as ■ the result of high flying, and, when he had apparently recovered, and went out over an English aerodrome, he found i . himself unequal even to a moderate effort, ; and came down with a crash. At last, therefore, man has produced a machine which may be greater than himself, save in exceptional instances, and it will be j necessary to exercise great care in the ' choice of men fitted for the task. But the j interesting point that still remains is this I —so far, no one has evolved a motor car ; I too powerful for a man to drive. Will j aeroplane construction progress until the i machine itself will be able to attain a . j height beyond the pilot's faculties? f Those who were privileged to hear Mr , R. L. Jones's recent lecture at the O.M.C.'s monthly -meeting speak highly of tho manner in which tho lecturer handled his subject. Mr Jones first showed an ordinary storage ignition, and then "took down ' a magneto. During j his remarks he stated that he did\ not j think magnetos should be oiled as fre- '. quently as the agents said they should, as ! ; the oil, if over-supplied, might find its , i way into the workings and , affect the ! current, ordinary visiting card was | a useful " too)" to show how far the j points should bo separated, from the central electrode. A spare ring should also be carried to put in the little circular ring which the magneto contained to make the break, in the event of the spring which was already there breaking. A watchmaker would* make a similar one out of a watch spring for about 3d. Mr Passmore pointed out that on one occasion he had broken his spring, and had removed it and jammed in a small piece of rubber. This had enabled him to reach home. Other systems of ignition were also rei ferred to, Mr Jones mentioning that American car men were divided in opinion as to which of the systems would finally hold the market. Not the least interesting part of the lecture was the cardboard illustration of the working of the make and brake. On the card was affixed the workings, with a retarding -lever, and by turning two bevelled brass wheels at the back of the card the principle stood out clearly before the eye. In replv to of question Mr Jones said that the distance between the make and brake should be about the .same as that of the plug points —viz., the thickness of a visiting card. A big battleplane has been recently constructed for the British Admiralty by Mr Handley Page, and while not as "large * as' the huge 1,200 h.p. Curtiss triplane delivered to the Admiralty, is still of cori-

siderablo size. It has a span of about 98ft, a length of 65ft, and a height of 20ft. Seats are, provided for five people, and mountings are availablo for three Lewis guns. The craft is propelled by' two 12cylinder Rolls-Royce motors of'-280 h.p. During a recent flight this battleplane carried 20 passengers and pilot to a height of 7,180 ft. 6