The Motorist.

New Zealand Illustrated Sporting & Dramatic Review, Volume XIII, Issue 786, 30 March 1905, Page 14

The Motorist.

(By “ Petrol ”)

MAKING A MOTOR. Now that motor cars are becoming so popular, a short description of the method of developing the power and delivering it to the road wheels should be of in’terest to the public. 1 have, therefore, endeavoured, in as few woids a s possible, to indicate the general ciples which apply to the engine and gears of most motor cars. The average motor car will do an ordinary dav’s journey of i-(> miles, without refilling either the water or petrol tanxs, though by earn ng spare petrol very much larger journeys may 7 be accomplished in a day- Some cars are driven by 7 electricity or steam, but by far the most popular and most successful is the petrol-driven car, owing to its greater efficiency’ and range, and to the ease with which its control may be mastered, many people only' re. Hiring one or two lessons to enacle them to drive successfully. Experience gained by the expenditure of a large amount of money, both in experiments and manufacture, has led to the almost exclusive adoption of the petrol motor working on the Otto cycle principle. These motors ate merely commercial gas engines. They certainly run much faster, the object of the higher speed being .to obtain the greatest Possible amount ofpporerw r er for the least possible weight. Care is, of course, taken that the requisite amount, of metal is used in the construction of the cylinders, to insure against bursting. Such a thing is practically unknown to the petrol engine, and in this respect, as well as in the ease of manipulation and simplicity, the up-to-date petrol engine leaves its old rival, the steam engine (with its necessary boiler) a long way in the rear. The question often addressed to the motorist by the uninitiated spectator, “Will she blow up ?” may, therefore, be answered with an emphatic “No !” For the benefit of those to whom the workirg of the petrol engine is unknown, I will briefly describe the Otto cycle as follows : — This cycle consists of four periods, viz., I.—The induction stroke, during which the charge of gas is drawn into cylinder by 7 the downward stro e of the piston. 2.—The compression stroke, during which the charge is compressed by the upward} stroke of the piston. 3.—The working stroke, during which the charge is fired, and the piston driven downward by the force of the explosion. 4. —The exhaust stroke, during which the burnt gases are discharged through the eihaust valve. These four strokes comprise two complete revolutions of the crank shaft. From the above it will be understood that, to enable .the charge to be drawn into the cylinder, and afterwards compressed, some descripticn of the inlet valve must be provided. This inlet valve usually 7 takes one of two forms, viz., the automatic or the mechanically’ operated. The former is held up to its seat by a light spring, the pressure of which is overcome by the vacuum created in the cycle on the downward induction stro 1 e of the piston. The mechanically operated inlet valve is operated by means of a cam, driven at half the speed of the engine. The opening and closing of this class of inlet valve

is, therefore, independent of the vacuum created in the c; Under, and may’ be timed to ta.. e place at the same point during every' induction stroke. The exhaust valve is in all cases mechanically operated by a cam, also driven at half the speed of the eng.ne. The successful wcr. ing of the eng.ne is largely dependent on the proper proportions of gas and air being obtained. Although this proportion may' \ary largelv, and the engine still run, yet the nearer the approach to the correct proportion the greater will be the e.i - ciency of the engine, and the greater power will it develop v ith the least expenditure of petrol. A carburetter is provided for the purpose of terming the gas. It usually consists of two chambers, one containing a flcat-controlkd valve, which maintains the petrol at a constant level in the other, or s..ray.ng chamber. 'j he explosive charge is formed in this chamber by the ar . eing drawn past a no„>le through hch the petrol sprays. The charge having been compressed in the cylinder is nred ( ,v means of an electric spark, for which purpose sparking-plugs ate provided. This spar., may be produced in se cr 1 ways, the method most usually 7 adopted is by 7 means of a storage cattery and induction coil, though Loth low and high tension magnetos are coming somewhat into use. The spark is caused to tax.e place at the correct moment by means of a commutator, ..hich completes the electric current at the moment when the spar a is required. This commutator is capable of movement, so that the spark may be made to place earlier or later, as required. In all motor cars it is the universal practice to water-jacket the engine. m small quantity of water is carried for this purpose, being kept cool by circulating through a radiator having a large surface exposed to the air. lhe power having keen developed by ihe engine, it s necessary’ to transmit it by some means to the road wheels. A friction clutch, operated by’ a foot pedal, is provided, so that the engine may be disconnected from the transmission gear with rapidity and ease by 7 merely depressing the foot-pedal. The friction clutch is connected with the primary shaft in the gear-box, and by means of a train of gear-wheels, the teeth of which sl.de into mesh with one reverse are usually obtained. With all sliding pinion-gears care is necessary to prevent damaging the teeth when changing the speed. From the gear-box the power is transmitted by an arbor shaft to the back axle in most cars of moderate power, though m the case of very’ large touring and racing cars the power is frequently transmitted from the gear-box bv means of side driving-cl air's. The rear wheels on gear-driven cars are fixed to the axle, which, in the letter cars, run on roller bearin s. For the purpose of silencing the noise made by the gases discharged from the engine, a silencer is presided. This is simplv a hollow cylicder with baffle plates in it—Captain Harley Tarrant, in the “Australasian.”

The motor cycle contest held in connection with the recent Dunlop Reliability Contest from Sydney 7 to Melbourne, emphasised one very 7 important feature of the motor cycle (writes “Auto”). Over the hilly N.S.W. section of the course the highpowered engines gave consideraole trouble from ever-heating, which generally resulted in the rider having to dismount and

push his 160 or 180 pounds up the mountain sides, which is harder work than one would wish his worst enemy, or thetaking of a spell until the engine had cooled. Pedalling was of very 7 little assistance up long, still hills, and could not keep the engine going at sufficient speed to deveilop even half the declared horse power. With the lighter-powered engine, and lighter cycle, far better progress was made over the hills—in many instances the 2 h.p. engine out-pacing the 3i h.p. motor. Again, on the rough roads the lighter machine was easier held up, and was not nearly so severe as the h< a'ierpowered cycles. # * * * 'lhe fact that the motor at twenty miles an hour is more tractable than a horsedrawn vehicle at eight miles per hour is very generally disregarded. To absolutely rule that the motor must not proceed at a faster rate than the horse travels is to n nder the value of inventions void, and to restrict advancement and development. And twenty 7 miles per hour is only a moderate speed for the automobile ; yet at all times the speed should be governed by the existing conditions, for while ten miles may 7 be the limit in the city 7, thereare times and places when a spei d a 1 ove five miles is absolutely 7 dangerous.

When the first annual report and bal-ance-sheet was placed before the members of the Automobile Club of V ictoria a v(>rv encouraging state of affairs was disclosed, the roll totalling 170 members, whilst the balance-sheet showed a profit of £lO7. Good work w a s accomplished by the club during its first year, and there is no doubt that the A.C.V. has a very prosperous career before it if is is conducted on similar lines to that laid do', n during the association’s first year. * * * * The motorist can help himself, and must do so, in order to steer clear of the worry and discomfort consequent on punctures and on undue wear and tear, with their accompanying expense. Increased wear and tear are bound to ensue owing to the employment of ty’res much too light for the engine power and load placed on them. The overloading of a tyre has precisely the same effect deflation. The increase m width of the tyre surface on the road increasestion, and generates more heat, to the injury of its wearing qualities. In addition to this, more engine power is required. to move the wheels. The tyre is a passive resister, and supports the> overload and overstrain until worn out hnd exhausted, when it collapses, receiving curses instead of praise for its heroic efforts to achieve the impossible. It may’ he stated as an

axiom that motorists find worry simply because they do not know how to employ tyres. Suitable tyres may cost a little more at first, but in the increase in price is trifling- when the freedom from anxiety and annoyance is rated at its full value in enhancing the pleasures of motoring. By "suitability” is meant pneumatic tyres possessing a guaranteed carrying capacity which, when multiplied by the four wheels. Kvill show a good margin over the weight of the car, fully loaded with its compliment of passengers. This tyre will have a double tread and increased strength of fabric to correspond The addition of the wearing-strip is not by any means the same thing, since the light car will have a lighter construction in fabric, and is not intended to stand the strain of an increased weight of tread. Put the car over the weighbridge, and allow for the extreme load likely to ,be carried. The greater the margin between the carrying capacity of the tyres and the total weight of the car —in favour of the tyros —the less the chance of punctures or blow-outs.