MOTORS AND MOTORING

Dominion, 14 March 1919, Page 9

MOTORS AND MOTORING

' :iiv "Clutch.")

Acceleration. "What," asks a motoring writer, "constitutes the chief factor in accelerating a motor-cycle from a stato of rest?" Most motorists off-luuid would hardly give the correct reply. The most important factor is tho gear ratio. Of course, tho engine itself plays, an all-important part, for without efficiency, hero, the energy necessary to cft'ect propulsioij.umst bo absent. Tho point, however, is that, Riven adequate power or cylinder tractive effort, tho rato at which road, speed can be built up.depends, upon the ratio of gearing between ,the driven and . tho driving members.- if. this ratio is a low one, speed is thb more rapidly built up, or, in other words, "acceleration" is improved; but after a certain point has been passed it cannot be further increasoil, unless,.of coiihs'e, a change is made from the lower goario a higher one.' A single-geared maohino must therefore be a compromise, a lid oilly 'whero a gear-box or'expandingpulley mechanism is present can the ideal be,readied.' This matter, of acceleration is regarded afl being of ;great importance in Bpeed work, where- the ability to "get off tho mark" smartly may make all the difference between winning' or losing tho event, a.ud it is also of special moment in the propulsion of trains ra.ihvn.vs. In this connection the electric locomotive scores heavily ovei 1 its, stwim rival, for tho reason that in.its case power is directly appliod to all (or several) of the axles and the wheels aro of smaller diameter than in the steam locomotive. An acceleration of oh& mile per minute. • if? Achievable without difficulty 'by meaiis of electricity,-but if -steam is the medium of -propulsion the design must ho a very Special one to realise such a rate of -progress. . ..... Two-Stroke Engines, In the future develijpment of the motorcycle there will anso' a Question requiring to be dealt with before matters have gone very far, says the "Motor-Cycle Trader." The two-stroke principle, which holds greator possibilities than many seem to imagine, is certainly capable .of further advancement, and there is no actual' reason why it should he almost entirely confined to low-powered machines. The objections raised against the high-powered, two-stroke engine are based more on thermal • than "mechanical" grounds, hut we have already, seen what, is possible of achievement in a popular model which, as it?-performances, have shown, is at least the equal of tho average. 5-G hip. four-stroke, even with sidecar attached. The particular machine to winch wo rofflr cannot b& sftid to nifirk tho limit in the upward direction of twnstrok's engine output.' Then again, although British designers may, not approve of American idea's in this particular form of construction, they ; will no. dolibt rdmit that what has been done in the I State.already is .sufficient to show that I the four-stroke principlo is not compnl- ! fiory of use when designing the heavier [ and more powerful models. For a time it was Customary to look upon the liori-jwntally-opposEil or ilßo deg._ enginft as a light-weight typo only,- mainly, for the reason that it was first popularised m that connection. ■ So, is it with the tvo-strokei whereas in point of. fact both it end the "opposed" engine nre.entirely suited.to the.needs of the. heavy, as .well sw the lighter models. It will be interesting to follow the evolution of opinion on these points,.and we shall be astonishM if at no ,verv distant date, the twostroke engine of 'inereiised iiower docs not figure' as a regularised type. Here and There. If drivers-would only learn it (says an ! American writer), the easiest' ■' way -to | avoid many gear changes is to make tho i ne-eessary ones quickly. By slowing down I the'engine to about sio revolutions at tile beginning of a hill' it -often; is-possible to save making an additional 'change later on, in addition to which one makes I a quicker climb, anyway. Also, tho early j change saves strain on the engine and transmitting parts. It will be a long time, according to an English authority, before any reduction in the cost of material, and. labour will make itself evident by a-redaction in the selling price of motor-cars manufactured in England, of given type and quality. The. maintenance of output 'by a large factory involves, heavy , stocks of material and large ; comiiiiUneiits..',..The,, material that comes in.t«-day„.does l not go out in the form of Y part'of a complete vehicle 10-mcrrow. Eight up,,to tho .present .moment the cost of material has remained substantially at war- maximum.-. - Were the cost to begin to drop immediately I many months would elapse before tho ef- | foot would be felt in the cost, and there- ( fore in tho price, : ;of ; the vehicle as a j whole. We all hope that later on lnanu- ! fftcturera-will be able to.quote lower j prices, hut- the decline at the best must I be gradual, and the saving effected. by ! iniying a new vehicle .in six; months' time i instead of now would therefore be very Ismail, if'it existed at all.. Thus the saving on first cost to be effected iiig is not likely to .be more than trifling, ifnless /ivo are prepared to" wjiit for- at least aVeaT, or possibly, more. ■ • . I To test a wheel for loose bearings jack it up and take hold, of .top find bottom spokes, pulling and pushing 'in opposite directions. If lio looseness is shoivn in this' way, try lifting the hub to see ;if there is play in that direction; If liny play is shown, tho bearings • must ho taken up. Don't grind the self-starter indefinitely (a trade journal enjoins). Ton wouldn't do it if you were ('.ranking by hand. If tlie .starter spins the engine, some other cause is preventing the latter from-gel-ting away under, its oivn power. If .you keep the starting switch closed indefinitely,- hopimr that at some revolution the engino will take Uiold.' yon may, be overlooking a shut-off'ignition-switch or tho absence of spark or petrol. • . - , There is a vel'.v simple remedy for leakage of water through the . material of mohair tons with which comparatively few motorists are familiar.. Tho'process of rubbing boiled linseed oil' into the material will render it waterproof. - Ligliting-up time: To-day, G.IG p.m.; next Friday., G.'l a.m.