Motor Notes

Hawke's Bay Tribune, Volume XX, Issue 264, 25 October 1930, Page 13

Motor Notes

MODERN DEVELOPMENTS. Many accepted practices of only a tow years back in the automobile industry are to-day only memories amongst old-time motorists and entirely unknown to the present generation of car owners. In early days, tiller steering was standard on one or two makes of cars, whilst such popular makes as the DeDion and Darracq had the change gear lever on a quadrant, set on the steering column under the steering wheel.. It is interesting to note that there is a definite tendency to revert to this practice. Acetylene headlamps were standard on all makes, with kerosene side-lights and taillights. Detachable or spare wheels, also demountable rims were unknown, and a roadside tyre repair was a laborious back-breaking job. Many a pioneer motorist was lucky if ho could effect a tvre repair—patching tube and often the casing—within an hour. Steel studded covers were popular with many motorists in those days. A handy auxiliary that used to be carried by some of the early motorists was a cylinder of compressed gas—CO. 2— carried in steel bottles; there being sufficient gas in a contained to inflate six to ten tyres, according to size of bottle. Such things as grease guns were undreamt of in the earlv days, and greasing a car was a long, tedious and often unsatisfactory job. Now, on some makes of cars, a push on a pedal automatically lubricates all neccessarv chassis points almost instanteously.

POWER LOSSES. Motorists will be surprised to learn that it is computed that about one car in every five, loses engine efficiency in some degree owing to petrol gas forming in the fuel line. The cause of this trouble is usually owing to the petrol lead running too close to the exhaust pipe, or tho carburettor, or the vacuum tank is overheated owing to high temperature under the bonnet; this has a tendency to boil petrol and the resulting gas forms into bubbles that interrupt the even flow of petrol. This causes the engine to lose power, misfire, and even sometimes to stop entirely owing to fuel starvation. It will surprise many car owners to learn that at about 00 degrees atmosphere temperature, the heat under the bonnet may climh as high as 230 degrees, whilst the temperature. of the carburettor jet may reach 175 degrees. This “Jet” figure was ascertained during recent tests where a carburetter made of glass was tested for petrol bubbles, under varying degrees of heat. In the tests it was found that the petrol bubbles, at high engine speed, were sucked through the jet with little effect on engine running, but once tho revs, got down, the bubbles increased in size, arid choked the small orifice of the jet. When it is pointed out that the volume of petrol gas is approximately 185 times greater than an equal weight of liquid petrol, it will be realised how impossible it is for the very small hole through the carburetter jet to nass sufficient gas to enable tho engine to function properly. . This explanation will probably elucidate for many motorists why their cars run so much better and smoother during cool weather, than when the thermometer figures register high To cure the trouble cited is in some cases a difficult matter, but where it is found that tho petrol lead runs close to the exhaust pipe or near tho exhaust box, ar’ gets unduly hot, this can be remedied bv lagging the exhaust pipe with asbestos cord, or by removing the petrol pipe to the opposite side of the chassis. A cure has been effected in some instances by fitting a larger petrol pine, and covering the vacuum tank with asbestos sheeting. A change of petrol will sometimes overcome the trouble, for the more volatile the fuel is, tlm readier it will form gas under heated conditions A heavier grade fuel may therefore imnrove matters, although it mav slightly affect starting of tho engine, but that trouble does not often worry Australian motorists during the summer months.

DISFIGURED CARS. Many of the open touring oars seen on the roads to-day have their appearance disfigured by either broken or cracked celluloid hood screens. At no time has this material been perfect' for automobile hoods, as it discolours and in our climate becomes brittle and consequently easily fractured. A better and more suitable material has long been wanted, for nothing is more unsightly on an otherwise well-kept car, than broken celluloid screens. If reports to hand from France are eventually borne out, it now looks as if a transparent material bag been evolved, that promises improvement in this direction. From Paris comes word of a synthetic flexible glass, which is stated to be an advance on anything of the kind yet produced. It is patented under the name “Similex” and is stated to be unsplinterable; also fire, damp, and acid proof. A French company has been formed to manufacture this flexible glass and no doubt in due course, this material, if proved satisfactory on the Continent, will be marketed in this country. GEAR-BOX CHANGES. In the old days when engine speeds were low and cars were short, the design of the propeller shaft was not a matter that worrhia the motor engineer much. All ne had to do was to provide a piece of round steel of a diameter sufficient to transmit the twist without fracture and with joints at each end to allow for the movements of the rear axle. The first change to upset this stats of affairs occurred when it became the fashion to build the gear-box in one unit with the engine. Naturally, this involved moving the 1 gear-box forwards to the extent of anything between Ift. and 18ins., so adding very materially to the length of the propeller shaft. Simultaneously, the wheel-base customary tor cars of medium size commenced to increase. The propeller shaft designer then had a new problem: apart from being faced with a 50 per cent, increase in the length of the propeller shaft, he had to allow for a very big increase in revolution speeds. Not everyone realises that when a car is moving in top gear the propeller shaft turns at exactly the same speed as the engine, and this may amount to 3,500 r.p.m., or more in quite ordinary cars. Mysterious vibrations are often traceable to the propeller shaft, which may be out of balance either through inaccuracies in the universal joints or through defects in the shaft itself. Thus it is not sufficient that the shaft should run true because this alone will not ensure freedom from vibration unless the material of the shaft be uniformly disposed around the centre of rotation. For examplo, most shafts are tubular: conseouentlv. it is very important that the thickness of the tube should he absolutely uniform throughout. If the hole in the centre is eccentric to the outer surface a centrifugal force will be set nn which will tend to cause whip and vibration. The design of tho universal joints is another important matter that has a considerable bearing on the efficient transmission of power to tho back wheels.

"OLD CROCKS” RACE. An interesting and amusing event in the form of an "old crooks” race was recently sandwiched into the programme of an automobile race meeting at Brooklands. England. Great was the merriment and laughter as 39 old cars—some dating back as far as 1896—took part in two groups in a speed event. Some of the old cars had heen a dwelling place for rats for 30 years past, whilst one had a tree grow through its chassis, ns it stood neglected in on orchard. The fastest time recorded was bv a 1903 "DeDietrich.” which averaged noarlv 44 m.n.h. for the race, and actuallv did a Inn of “Rrooklands” at 58 m.p.h. Other old-timers to perform well wore a 1004 Rnlls-Rovce. a 1902 Daimler, a 1899 "Progress” Voiturette, a 1896 Bena and a 1902 DeDion. TWO NEW SDHSTITUTFS FOR PETROL. Two substitutes for petrol as a motor fuel are being studied, one in Switzerland and one by the United States Bureau of Mines, The Swiss fuel is called “gasolene” and is manufactured from wood charcoal. Tt is said to show an economy of 70 per cent, in operation. The U.S. substitute is petrol made from shale oil. Refined shale oil gasolene under test developed more than 4 per cent, electrical horse-power than the ordinary petrol.