MOTOR AND CYCLE.

Taranaki Daily News, 21 July 1917, Page 10

MOTOR AND CYCLE.

NICWS AND NOTKS. As a military ineligible, write- a wellknown Knglish motor expert, I have tried to find any sort of war work within my scope, and have found sundry opportunities of adjusting privately owned cars belonging to people engaged on duties of national importance who were unable to obtain the services of professional mechanics. These job- have taught me a great deal, and of all the impressions which they have made on my mind, the chief is that the very partial accessibility which exists on the

average chassis is mainly accidental in character. Scrcral brains co-operate to produce a car, but in few cases are there many signs that it was the special business of a particular brain to facilitate adjustments, repairs and re-assembty, so as to cheapen and simplify the maintenance of a car in running order, whether by amateur or professional mechanics. Vestiges of forethought are occasionally encountered, especially in respect of the location of the magneto and carburettor. But, as a rule the en-1 gincer who designs the chassis is perfectly satisfied if the. details of the naked chassis can be manipulated with tolerable case by trained mechanics, using a special set of tools, and familiar with the construction of every part and the order In which it "goes on." The designer of the body appears to be perfectly satisfied if his coachbuilders under similar circumstances, with every part new and clean, can erect the body in a reasonable time, and so forth. But I have never yet encountered a chassis which made me say "The fellow who sells tliis car runs a duplicate himself, does all his own work on it, and ruthlessly eliminates every detail which proves a source of trouble or delay by reason of its position and arrangement." Tho fact is we are hypnotised by the obsessions of the cycle and carriage-building trades; we have not begun to realise that automobile accessibility is a science in itself; we have made no inventions in this line, and anybody who -hankers after innovations is always deterred by the thought of cost. Tam convinced

that sooner or later the motor industry will bo driven by empctition to work out a whole new scries of mechanical clip* and fasteners suited to its special needs, and when our universities establish their faculties of automobile engineering there will lie a special chair for accessibility. One result of the present shortage and high price of petrol should be to focus more and more attention upon the proMem? of carburation. Tlie carburettor as at present designed, certainly jmvcs good results when using the fuels to which we have been accustomed in past years, but the number of motor vehicles put into use is being increased at an enormous rate each year, and the inroads which are beinjr made into the limited stores of motor spirit, as we know it at present, suggest that it is vital that every effort should be made to ensure that none of it is wasted. Tn America where the fuel problem is becoming acute, it has been borne in upon those who have been investigating the subject, that the carburettor of today has ceased to be more than a measuring device, and that the true vaporisation takes place in the intake manifold. This suggests that ideas regarding carburettors are in great need for revision in the direction of the fitting being eon sidered not merely as a unit by itself, but as a part, of a complete vaporising device. This view is borne out by experiments which were carried out some time ago in Chicago. Various carburet-

tors wore, tested, and in order to observe the notion of the spirit n. glass boll was arranged over the carburettor oirtlct so that the suction of the engine jfell on the jot in the, usual maimer. but tile resulting mixture wa- thrown into the glass hell before being drawn into the engine. Tt was observed that at low throttle openings tlie inporisation was practically complete, the mixture entering the engine in the form of a fog. But as the. throttle was opened and the vacuum began to drop, instead of :i fog, the resulting mixture became a spray carrying large globules of rawgasoline to the engine. This raw gasoJine was caught by the bends and elbows in the inlet pipe, and. collecting into pools, gradually ran down into tlie

cylinders. It wa< found that the temperature to give a good mixture was W.t degrees Frtr. To attain this it was necessai y for the entering air to liave a temperature of about 152 degrees Fabr.

in order to compensate for the +3 degrees drop in temperature which took place during vaporisation. As is wellknown, when using petrol in a cold engine, it is necessary to open the full jet to ot't a big supply of fuel in order that the lighter (dements may make up for the non-vaporisation of the heavier elements. The latter remains in liquid form and travels along to the engine, being unevenly distributed to the various cylinders and burnt incompletely with a deposit of carbon. This indicates tho necessity for the installation of an arrangement for pre-heating the intake manifold, in order to secure thorough vaporisation of the whole oi the fuel. If this were done it would be poss ible to use smaller engines, for it has been calculated that engines are usually so large for their work that 98 per cent. of their operation takes place wniTe the charge is greatly reduced by throttling. This decreases the amount of vapor charge necessary and thus lowers the temperature necessary to run. For intance, -when the throttle is closed so that there is only S6 per cent, of a full air -harge a complete vapor charge could exist at 69 degrees Fahr., and the temperaturo of tho incoming air need he onlv 111 degrees 'Fahr. As the- tendency is for the utilisation of the heavier grades of motor spirit, and at considerably increased prices over the old spirits, which easily vaporised at ordinary atmospheric pressures, it is surely opportune for the production of carburettors, or rather vaporising devices, which shall permit of tho utmost power oeing obtained from the fuel used. Wet sparking plugs arc an annoyance to say the least—yet they are of frequent occurrence on a motor-cycle. A tip that works out well—especially so where the plugs are set upright in the cylinder—is to protect the plug with a dome of brass. A) half of a brass ball from a decorative curtain pole end can be ,bought at any housefurnishing store and is well adapted for the purpose. The spun hemispheres are held together simply hy friction and arc, easily separated. Simply drill a small hole for the terminal screw and screw the shield in place with the terminal nut. Tho decive, aside from keeping the plug free from the least trace of moisture sets as a heat radiator, considerably reducing the working temparture of the plug and adding to its life as a matter of coursp.

When one watches a motor car turning a corner at speed, the strain on the lyres is very noticeable. A Californian profesMir recently made some tests to determine the. amount of thrust sustained by the tyre at various speeds, die found that a car weighing iSOO lbs., taking a curve of .")0 feet radius as 4m.p.h. Imposed practically no additional strain on the tyres, as the contrifugal tendency of the car is lost or absorbed in the tyre structure at that speed. When the ,amc car takes the curve at "20 m.p.h. not only is most of the 3500 lbs of the car thrown upon the two outer tvres, but in addition there is a contrifugal load or side thrust of about 1-100 lbs or a force of l>b\> lbs per tyre, applied in such a way as to tend to roll tin; tyre oil' the rim. This means that there Is an extra force of about 700 lbs trying to destroy the tyre at the moment when it is being called upon to support almost twice the load which is carried on the straight and for which it was designed. Taking curves slowly, therefore, takes away the most serious of the causes of rim cutting and deterioration of the side walls of the cover. The motorist who drives around corners slowly adds very considerably to the lire of his tyres and gains financially, for his tyre upkeep is reduced.