MOTORING

Nelson Evening Mail, Volume LVI, 13 June 1925, Page 9

MOTORING

CHARABANC, LORRY, AND BUS EVOLUTION EIGHT WHEELS AND ELECTRIC TRANSMISSION (By H. Massac Buist) LONDON, May 1 The B tory of the evolution of motoring iv that many desirable mechanical features are nevertheless destined never to come into use because the period necessary to develop them to a. commercial stage is so long that, in the meantime, other apparatus, theoretically ottering nothing like as good possibilities, is nevertheless eommcrcialivcd to an extent sufficient to serve the purpose., lake the sliding spur type gearbox, than which no part, of early ears eras more Liable, ur costly, What were the alternative?? Petrol-electrical transmission, hydraulic ear transmission, and so forth. Having had experience of various examples of those two systems in tentative, been nee experimental, lurm, nearly a score of years ago. I can appreciate how if has come about that neither has stood any chance against the exolved sliding spur change speed gear because on many and so costly stages of evolution have to he passed through to attain iho desired results and. in the interval, the motor vehicle buying public could nof be, kept waiting. Therefore, the first motor cars that had reliable sliding spur ivpo gearboxes had them fashioned of metal which actually cost about, its weight in silver. Hut no sooner had the light metal, and the right method of treating it been devised, together with a piaefieal scheme of design, than the demand became so great- that, it was possible to commercialise (be materials, and standardise the methods of production, so That the cheapest car nowaday;has gem's designed and made "bettor of better materials more intelligently treated than the dearest motor car of oven a dozen years ago. ADVA NTA GES CL AIMED Rut this dues not mean tha-t the sliding spur typo of gearbox will he universal practice indefinitely for ail classes of motor vehicles. Evolution depends on the development of uses for the motor vehicle. Tc-dav we regard the propulsion of the passenger-car as requiring negligible force compared, for example, with propelling a lorry with trailer, or a charabanc, or an omnibus. A feature of omnibus, service, for exaple, is continual stopping, starting, accelerating, and stopipng again by contrast with the more or less even flow of touring by private passenger-car. Likewise, generally charabanc services tiro run over routes that occasion the lengthy use of indirect- gears. Therefore, problems of new style power transmission continue to engage the attention of automobile engineers. For instance, the Versa re Company has built a ten-ton eight wheel experimental omnibus chassis with petrol electric drive especially for the purpose of dealing with the increasing loads awaiting transportation by utility motor vehicles. The advantages sought in the eight wheel vehicle, the frame of which has as many springs, are that it should be possible to carry greater loads in synchronism with reducing tho weight per inch of tyre width, Further, it- is believed that shocks duo to the impact of the wheels with obstructions, or irregularities, of the l ’ad surface will he of less intensity to ‘he chassis, and that alike the pounding effect on the road and the stresses on the chassis body due to road shocks will be reduced materially, thereby lengthening the life of the highway and of vehicle parts. 'Hitherto, the problem of designing an effective steering mechanism has prevented designers being more hold in the matter of attempting eight wheel vehicles, which must necessarily ho of 'great length yet capable of being manoeuvred in narrow street’s and on winding thoroughfares. In tho case of tho Versace, which lias an overall length of 36 ft. the vehicle practically presents the appearance of a Pullman car with four wheeled bogeys at either end.

STEERING PROBLEMS The front pair of wheels on tho forward truck, as it is called—or bogeys—are turned by tho driver in much tho .game way as in ordinary four wheel vehicle practice. The two front wheels of tile rear truck are provided with an automatic device that allows knuckle steering to be used. Tho cross links to these wheels are attached to a small wheel mounted slightly in front of and in the centre of the axle, the control of which- small wheel is provided by _a telescopic rod and attached to a point on the frame about 7 feet in front of the axle. In other words, both these trucks are provided with a fifth wheel which allows of swinging them through an angle of 45 degrees to either side of the straight ahead position, tho arrangement making it possible to turn tho bus in comparatively shall compass aud, it is also claimed, to prevent side-slipping. The use of swivel type trucks, and the weight and size of ‘tho vehicle, make it desirable to provide electric transmission. A lOt) h.p. engine drives the generator, which is supplemented by two motors, one on each bogey. The engine having been started, the driver throw's tlie motor control lever into- one of the operating positions, then, tho vehicle is ready to move, the engine throttle, being practically the only control in use regularly. Variation of engine speed is sufficient to produce the desired voltages, lienee bus operating speeds. The field resistor unit is used only when climbing steep grades, or to achieve maximum acceleration under heavy loads. The master-controller, connecting the motors to the generator, corresponds to the gear change lever on an ordinary motor vehicle, but, apparently, it lias to be used less often. Grades up to 4 per cent can be ascended with the motors in parallel. Despite tho extraordinarily rapid and assured growth of utility motoring in this country, and especially the great increase of the moving of heavy loads by road at night time, nevertheless one feels that the average British thoroughfare is not ready suitable for such vast classes of vehicles. ROADS AND RUNNING COSTS It has often been suggested by tho writer that the cost of motor taxation in those Islands is not onerous provided wo get roads suitable for motor vehicles because that would represent a very great saving in expense, alike as regards fuel consumption and tyre wear, to say nntliiug of shackle-bolf s and other parts of the chassis. Unfortunately, however, no experiments have been carried out in this country that have a direct bearing on proving this contention. But the Engineering Experiment Section of the. State College of Washington, U.S.A., reports that tests carried out to determine' whether the saving in fuel and tyre wear and tear on good roads warranted the greater cost, of them or, more precisely, what amount of traffic an approved road of a given type must carry in order that the additional cost of it may bo compensated for by savings due to reduced fuel consumption and tyro wear, show that tyre tread wear is 56 times as great on pure macadam as it is on concrete roads, and that the consumption of fuel is 50 per cent higher on roads of bad surface than on good. Throughout the

lest the speed was kept- as. nearly consistent as possible, end special precautions were taken to avoid running through mudlmles, or any other accumulations of moisture on the roadway. The need for this was emphasised when a- tyre thus moisTer-cd near the end of a run absorbed moisture equal in weight to the wear of 12 miles of macadam. It was found that atmospheric temperature has a considerable effect on the rate of tyre wear, therefore temporal lire measurements were made during each run. '1 hr tests prove that the rate of tyre wear increases with the speed of the vehicle. The explanations are that at high speed there is- more violent impact of tyres against road ohsitructions. besides which there is nuv-’e bouncing of the. wheels on and off the road wavs, followed by spin ning of Ihe driving wheel and grinding of the tvre tread against the road surface vh n it makes’ contact- with it ag;vu. Ihe experiments show a continuous increa r in fuel consumption with increaes of speed, which is to he looked for in face of the law whereby resistance to forward travel increase? as flic square of the speed. i

THE USED CAR PROBLEM The Ford Company , which recently assembled the 250,000 th car built in f hi j country, is continually expanding its enterprise in America. as may he judged fimn tile fact that then l is now a tri-wneklv aeroplane service carrying 1.03(1 lie load of Ford ear parts by air from Henry Ford s aviation ground in Detroit pi Chicago. This scheme is to he do- doped rapidly by organising similar supply service:; to Min.ncapolis. St. Paul, and a number of other centre?’. Further, on the aviation ground in question there is being erected a- large mooring lover f.;r airships. In other words.’, the great mass production car builder is giving eerie-is attention to the commercialisation of aviial travel. In synchronism, he has just launched in America what is styled a national list'd car sales policy. This is designed with the twofold object of stabilising the prices of second-hand Ford vehicles strictiy on tiic basis of unused transportation and of bringing all such bns.inesfi to authorised Ford agents. Under this plan each car sold will hear a seal guaranteeing it to he in sound condition and the- agents arc required to see that they give ser\ice. Tl.c buyer lias a week's trial and a month's guarantee. The factory will k'-ep a close cheek on valuation hv all its agents, and will further insist that all its dealers shall make the sale of used cars yield them a- profit. Edsel Ford, soq of the founder of the business and the. present President of the Company, said by wav of explaining tho new police : ‘'Every used car represents so much unused transportation and is of value to someone. Our dealer through his intimate knowledge of the car should he the best, judge as to tho value of this unused transportation and better able than anyone else to determine a price on the mileage the car may yet. bo expected to bo capable of traversing. For this advantage the dealer is prepared to give the buyer of such a car benefits not- likely to he obtained elsewhere. If i ocotidil inning is necessary, lie has the work done by trained Ford mechanics using improved equipment and genuine Ford parts. With these economies and advantages, lie is able to offer the.used car to the buyer at a low cost and with a. guarantee covering its. mechanical fitness.”

There would seem to he hero the basis of certain possibilities in regard to developing the used car proposition in this country where, however, the situation is appallingly complicated by reason of the rapid changing of models and the extraordinary number of types marketed by individual firms, also, of course, by the unprecedentedly numerous makes of cars on the market, there being no other country in the world which presents such a complicated situation. Over 80 firms are supposed to he building motor cars in (iiis country; the number of imported cars is far in excess of that-, and scarcely any firm confines itself to the production of one model only. Hence the trouble.