MOTOR AND CYCLE.

Taranaki Daily News, 16 July 1921, Page 10

MOTOR AND CYCLE.

NEWS AND NOTES.

A cablegram from America innounces the victory of T. Milton in the 500 milea Indianapolis Motor Car Track Contest, which was decided on May 30. This is the classic speed event of America and carries with the trophy an amount exceeding £4OOO to the winner; whilst the total prize list amounts td nearly £lO,OOO. Milton’s time for the 500 miles was 5 hours 17 minutes, some 23 minutes faster than G. Chevrolet’s winning drive last year. Milton’s performance is easily a record for the event, and his average of nearly 94 miles an hour for the full distance is a remarkable one. His mount would probably be a “straight eight” cylinder “Dueaenberg”—an American car—upon which he has achieved many fine performances on American speedways. Ralph de Palma again put up a spectacular drive, leading for half the distance and then retiring thrbugh engine troubles. Last year he was nearly 5 miles in the lead at 400 miles when hia car caught fire, costing him the race. GRAND’PRIX RACE. In view of the forthcoming Grand Prix road race to he decided over the Le Mans circuit in France next month, Milton’s success will enhance the interest in this classic road contest, for he is one of the team of drivers selected to drive the “Duesenbergs,” America’s only representatives in the race. The ear driven by Milton was built to conform with the Grand Prix regulations, consequently its success promises well for its chance of carrying off the great French event. At the same time it has to be recognised that a road contest with its sharp corners etc., is a vastly different proposition to a race around a two miles banked circuit, such as ‘the Indianapolis Speedway. At all events Milton’s success appears to give America a chance to redeem its European reputation in classic road contests, for in the past the U.S.A, representatives have been practically outclassed in these events, in which the French and Ger- ! man car manufacturers and drivers ! excel.

According to evidence given at the Coroner’s enquiry into H. Parson’s fatal c. ecident on the Epping Road near Melbourne. the throwing of a stone at some loose horses being driven along the road, caused the collision that resulted jn the death of the finest motor cycle rider Australia has produced. That Parsons was travelling at a high speed was evident, for he was picked up 46 yards from the point of accident, whilst his machine ricochetted along the road some eighty yards. It is proposed to erect (by his many admirers) a memorial to his memory. AN ELUSIVE POWER. Horse-power is an elusive term to many motorists. When a beginner buys a ear he asks the horse-power and is Usually told its rating according to formulae. In many instances he obtains a car considerably higher powered than anticipated, as many of the horse-power •formulae take no account of engine speed and base thfeir results on bore and stroke only. Such formulae can only be approximately accurate at the predetermined speed for which they were drawn up. They give some indication of what an engine should do under certain conditions, but that is about all. There is, however, a difficulty in including r.p.m. in a formula, because if an engine gives 20 b.p.h. at 2,000 r.p.m. it by no means follows that it will give 40 b.p.h. at 4,000 r.m.p. In fact all formulae for arriving at the horse-opewer of any engine from the R.A.C. rating upwards are only approximations useful as a means of comparison, but nothing more. That being so, why not make a formulae as simple as possible, say, let every 100 c.c. of the total piston displacement equal one horsepower? Every modern engine should be capable of this. If it is not, it should be overhauled, for something must be radically wrong with it.- In fine, what the car owner wants is good performance for moderate fuel consumption and the ability to climb fast rather than the ability to climb on top gear. When all is said and done, and we come doivn to the bedrock, what we want is power. In some engines this is obtained in one way and in others in another way. The Americans are inclined to favor size, while the British pin their faith to efficiency. One engine may be capable of high power because of its piston area; another in virtue of its capacity to “rev” at a high speed. Horse-power 5 is after all, simply the rate of doing work, and consequently an engine that can move quickly need not put so much 1 power into every stroke. The product of the mean effective pressure on the piston heads and the piston velocity will give an indication of the horse-power; if one of these factors can be increased the other can be correspondingly decreased. If two cars of equal weight and wind resistance are ascending the same hili side by side, the two engines are obviously at that moment exerting the same horse-power, although they may be very different in size or, being in equal size, are revolving at different speeds. It is instructive to note that some of the 15 h.p. and 18 h.p. cars on the Australian market develop from 45 to 50 h.p. on the brake.

SLIPPING CLUTCH. There is one very annoying trouble which at one time or another seems to fall to the lot of many motor cyclists, and that is a slipping ’ clutch. When it sets in, it takes all the pleasure out of riding, it is worse than a slipping belt, for that, at least, can he cured iu a few minutes, whereas the origin of the clutch trouble is often very elusive and difficult to trace. On present day machines fitted with a countershaft gearbox, the dry plate clutch is invariably located inside the big chain sprocket driven direct from the engine. Often it is enclosed by the chain case. A dry plate clutch consists of a series of plates which, when the clutch is “in” are pressed together by a spring or springs, and require no “Declutching” means releasing the pressure of the springs and so relieving the friction between the plates, which immediately cease to grip one another, thereby preventing the transmission of power from the engine to the gearbox. The number of plates comprised in the clutch varies according to the engine power. A lightweight machine may have only three plates, whilst a powerful anti heavy passenger motor cycle usually has five, and occasionally seven. The number is never even, since the driving plates are interposed between those they drive. The driving plates carry a friction material either a lining riveted on,

or in the form of plugs inserted in the perforated clutch plates. This material is usually Ferodo (or of a similar nature), and in clutches of the plug type, cork and thermoid are generally employed. In the case of a five plate clutch, there are three plain steel dises, each connected solidly with the gearbox mainshaft, and two lined plates driven by the engine, when the clutch is engaged, the pressure of the spring or springs binds all the plates together as one, and thus the drive is transmitted direct from engine to gearbox. The tracing of clutch slip therefore resolves itself into discovering at what point the plates are not being held in firm contact. Before dissembling the clutch to search for hidden trouble, first make quite certain that the fault does not lie on the surface. In quite a large proportion of cases of clutch slip the reason lies in the operating mechanism. The bell-crank which conveys the motion of the clutch pedal should not bear on the thrust pin when the clutch is “in.” It should have just a little slack or lost motion. The operating mechanism should be tested for free working right through to the bell-crank; occasionally a stiff pedal or sticky bearing in the control is sufficient to prevent the clutch going right home. Assuming the fault does not lie here, the thrust pin should be similarly tested for freeness in the gearbox* mainshaft. Although the foregoing may seem trivial and obvious points, yet a combination of them all can cause a very puzzling trouble—that of slowness on the part of the clutch in taking up the drive on middle and top gears. However, if the clutch still slips when the thrust pin is completely withdrawn from the gearbox, investigations must be pursued into the clutch itself. Removing the chain case, or that portion of it which covers the countershaft, the clutch housing is exposed to view. If one large spring is employed the action of screwing up the nut on the end of the shaft will increase the pressure on the plates, and this should be tried before proceeding further. If the slip still persists then the clutch has to ‘be taken down. It may then be found that the plates are fouling, caused through‘wear of friction material, the offending plates usually bearing polished spots. A few rubs with a fine file will usually remedy this trouble. Again oil may have got on to the plates, when slipping is inevitable. Washing clutch out with some hot water and soda will genereally remove the oil. Should the slipping not be remedied by the attention mentioned, then it is better to get a mechanic to overhaul the clutch. A GREAT INDUSTRY.

The automobile business is the largest manufacturing business of finished goods in the world. This year the total volume of the automobile, accessory and supply business in America alone will reach £880,000,000, of which over £400,000,000 will represent passenger cars and trucks. There is one car in use for approximately every 13 persons in the United States, as compared with one for every 268 an England, 402 in France, 684 in Germany, and 5,300 in Russia. Europe has 449,000,000 people and only 437,000 automobiles. It is estimated that 45 per cent, of the automobiles sold in America are bought by farmers and the inhabitants of small towns. There are about 800,000 motor trucks in operation in the United States, hauling an average of 4£ tons per day each, which amount to a total of 3,000,000 tons per day, or 360,000,000 tons per year. Figures show that the average ton-mile cost of motor truck haulage is about ninepence in America. Haulage by horse is estimated to cost Is per ton-mile, and it is said that truck haulage has released 3,600,000 horses for various other purposes in the United States. The automobile accessory and. supply business, including tyres,, petrol, and oil, has reached a volume greater than that of the automobile itself.

IGNITION TROUBLES. Many cages of ignition trouble have been traced to the use of improper spark plugs or to faulty location of these members. Manufacturers of spark plugs have given the matter of location considerable thought during recent years, and the endeavor is to produce a plug specially designed or adapted for the motor for which it is to be used. The spark plug shell or base is constructed so that spark points will project into the combustion chamber. It is also important to make provision for proper cooling of the spark plug. This last named factor is an important one that is seldom given consideration by owners or repairmen who change the spark plugs without making sure that they are adapted to the motor. To obtain the greatest efficiency from the explosion it is important that the spark, points project into the combustion chamber in such a way that they he surrounded with cool gas. If the gap of the plug is located in a recess or pocket, dead gas is apt to accumulate about the joints, and combustion will be ifiuch slower than it would be with the spark plug, projecting into the intake chamber, permitting the spark to take place in fresh mixture and promote rapid spread of ignition flame, It will be apparent that with a projection from the plug body having a space around it in which the hot gases may collect, the plug will heat up much quicker than the mounting in which the heat will be conducted away by the cooling water. A plug that becomes heated will tend to soot up and carbonise muth quicker than one in which provisions have been made for proper cooling.