MOTORS AND MOTORING

Dominion, Volume 11, Issue 287, 23 August 1918, Page 9

MOTORS AND MOTORING

—,— <Hy "Clutch.")

| • Cp/rc of Tyres. The surface of a well-worn cover will' bo found cut in many different ways as the result of wear; one kind of murk, however, betrays tho bad driver—a scries <>f long parallel lines or scratches, sometimes even (lie actual surface scraped away, due to the wheels • having been locked by violent braking and the car | having slid forward sledgewise on one section of tho tyre. The preservation of a motor tyre involves rather a curious contradiction, for while,'as a general rule, water and damp are favourable to tho rubber of which tho tube and cover are composed (6omo kinds of rubber being preserved by immersion in water for long periods), it is highly destructive to the other essential part of the tyre—the cotton fabric foundation. The object of rubber in a tyre is to give resilience and take the wc<ir, but without the support of a fabric the pneumatic tyre could not exist. The mniu object, therefore, of nil attention given to tyres should he to maintain a Eound fabric, for with this not only can good retreads he made, butmany forms of external injury In the tread or walls can ho successfully repaired by vulcanising. A handy instrument for probing and cleaning tho dirt out of cover cuts is the tang end of a small file; with this one can soon tell by feel if the cut litis reached tho canvas, but the probing should ho done gently, as it is easy to puncture the tube inside if tho fabric happens to havo been cut right through. Any form of injury to the canvas is worth attention, and this will vary according to the resources of tho owner and the nature of the damage, irotn ordinary tyre stopping to vulcanising new pieces on the inside to replaco rolled layers of canvas. Whether it is worth spending much lime over superficial cuts with tyre stopping, which' can seldom be relied on as a permanent cure, is a matter for the individual owner to judge. In dealing with either tho rubber or the canvas, it is important to see that they are dry before attempting repairs. Csrburation. No one needs to bo told that the great object of mngr.eto designers is to produce tho largest mid hottest spark possible, in order to get the most complete combustion at the determined ignition moment ~ . . Steadily since the old days of the surface wick and 'lick-up" carburettors -the Maybach. spouter is. not the least of tho Bochc crime's—wo have been forgetting that the other party to the deal is carburation. Now spray or atomise by all means, if you can do it right on the spot, so dead close up to the combustion space and tho ignition moment that it becomes an operation of the working cycle. It is probably tho more scientific and economical way, especially with constant speed motors'. And, making the gravity question all hut negligible as it does, it gives you a far greater choice of fuels. Only don't imagine you are even vapourising tho fuel, much less carburotting any air. You are making . . . a heat expansion engine of it, an lntexnal-combustiuh engine, if yon will, slow or fast, bitf nothing more. An explosion motor never. Yet if you attempt to cotfLbine tho conventionally advertised M epouter with, the induction 01 an explosion motor, heaven knows what se,ft of crossbred you are begetting. • • ■ Would it not bo better, then, to try first to design a true gasifying device that really corburates?-"Artifcx" »n A Tho Auto."

F/übber. Middle-aged people, and those older, but comparatively few of tho younger generation, will recognise in tho terms 1 gum elastic" the substance with which their motor and cycle wheels are shod. Kubber in those early days was a word rarely howd, while commercially it waa known as caoutchouc, and was iised only in sma/.l quantities for general purposes. J hero; as now, the term "india rubber" was usually confined to the substances used for erasing ink and lead pencil '"'.irks; indeed, up till about 1829, rubber wus used, practically, for no other purpose. It was not \mtil the discovery ' of tne process, of vulcanisation, about ISI3, that the possibilities of the wonderful natural product, began to be tooogui6cd. Two chemists, working inde-pemlcntly-an Englishman, named Handfock, and Charles Goodyear, an Ameri-can-discovered that by mixing the raw material with sulphur, and heating it to about 300deg. its elasticity was very much increased, and that it was to ii I great extent rendered immune from iho effects of cold or heat. When cold, natural or pure rubber becomes bard, and loses elasticity, while it becomes soft and viscid in heat. For a long period 5 tlie imports into England were small- , /Kl tons in 1552, 2385 tons in 1862, and I 78,55 in 1872. It was all nntural-<;rown | 'rubber, coming principally from Bntzil--1 lan and other South American forests, and in small quantities from South Africa, Mauritius, and, India. Plantation rubber was unknown, and is, indeed, a very modem development. The world's production of rubber in IS-06 was (•0,210 tons, of which only 51(1 tons was plantation rubber. In 1917 the production showed a huge increase—2o7,o<M torn) —of which the plantations furnished 20-1,0(10 tons. Had it not been for the unavoidable restriction of output duo to the war, the yield of plantation rubber would have shown another largo increase. John Doyd-Duulop's idea of fitting bicyclo wheels with inflated rubber tyres paved tho way for their uso on motor-car wheels, laid tho foundation for the present tremendous demand for r>.'bber tho world over, and led to its exploitation for many other purposes. Here and There. Writing in the '"Light Car" on the question of the decarbonising properties of_ water, Mr. J. 41. Heldt observes that: —"Injection of water stops knocking, but does sj by depressing the temperature of the compressed charge. Carbon certainly does not dissolve in water, and the only way in which the water could remove it would be by a flushing action. But with the infinitesimal quantities in (lie wafer is generally admitted, and its almost instant transformation into superheated steam, it seems to get vcrv little opportunity to act as a vehicle ior the carbon. However, as long as carbon does not cause any premature ignition ond consequent knocking it is rather beneficial than otherwise." America is providing between 50,000 and 00,000 niotor trucks for every million soldiers she sends to France. These trucks aro required to transport goods, r-mmur.ition, etc., some 350 to 500 miles from the U.S.A. docks, near Bordeaux to the American lilies. .The largest motor plant in the world is being erected in a central French city, to care and look after this huge army of trucks, the place being so estensivo that bicycles and roller skates will be used to get around tlio works.

lo prevent the possibility of using all the spirit in tho tank a device has been invented wherein a lever controls me level of tho supply pipe inside the tank. U the engine "peters" out, tho filler cap ol the tank ig removed and the pipe pressed down by a lever. The lever must be replaced before a funnel can bo inserted for filling up. • • An annoying troublo that not infrequently worries motorist's is tho sticking of valves, especially exhaust valves, which run .hotter than tho inlet valve, and are hard to keep in good order. When an exhaust valve sticks, and does not closely properly there is a leakage, and a consequent loss of compression, that manifests itself in baffling symptoms, so that it is difficult to locate the real trouble. Usually it is assumed that the valve requires grinding in; but before this operation is attempted it is well to examine the stem of the valve closely to- sec that the trouble is not theru, which is mostly tho case. An accumulation of burnt-on carbon will usually be found on tho stem, and this must be removed by a file and emery cloth, and tho valvo stem also cleaned, until its original colour js restored. The guide must also be well cleaned, and reamed out with a tool of proper size. This treatment, will prolong the life of the valve, save much uimeii'ssarv grinding, and cause the motor to operate better. Lightins-up time.:—To-day, 5.16 n.m. Next Friday, 5.2:1 p.m.