MOTOR & CYCLE.

Taranaki Daily News, 22 May 1920, Page 11

MOTOR & CYCLE.

ttEWS AND NOTES ' Despite the fact that a prize of £ 1000 was offered by the English Automobile Association for the best system of utilising coal gas as a fuel for motor cars, no invention or system was forthcoming, worthy of being awarded the prize. As coal gag only costs about half the price of petrol as a propellant it is disappointing that nothing practical was brought to light. The greatest difficulty appears to be the storage and compression of the gas, but maybe something will yet be forthcoming to enable this economical fuel to be applied to automobile use in a practical manner. According to calculations which have recently been carried out in America to determine braking effect, the fbllowing figures have been evolved as the minimum distances in which a car can be pulled up at various speeds:—At 10 miles per hour, the distance will be 9.2 ft; 15m.p.h. 20.8 ft; 20 m.p.h., 37ft; 25 m.p.h., 58ft; 30 m.p.h., 83 3ft; 35 m.p.h., 113 ft; 40 m.p.h., 14Sft; 50 m.p.h,, 231 ft. The question has been raised in England as to whether brake compensation is'necessary. By compensation is meant that application of the aide brake lever equal braking force is applied to the back wheels at the same moment. The matter is one of great interest to all motorists. One expert who was sceptical of the practicability of braking independently on one back wheel at a time, conducted a series of experiments, and his report makes interesting reading. "I was asked to go out on a car in which the brakes were fitted independently to each rear wheel, having first been assured that very extensive tests had been made on roads with surfaces of every description and all that had been proved was that, while the broking system was exceedingly effective, far more so than on a standard car, there was no tendency to skid; in fact, the car pulled «p in difficult circumstances with greater certainty and less risk than when the brakes on the same car were properly compensated. The proof of the pudding is always in the eating thereof, and I fixed on a day which I hoped, under our normal weather conditions, would provide, all the thrills desirable in the way of first-class greasy surfaces. Unfortunately, however, the weather turned out to be fine, and the only suitable place for a test that coudl be found was a main road where the cement road was beautifully polished; the kind of road on which, if one locked the brakes and spun the steering wheel round, the car would make a complete circle without hesitation. There is no need to mention the name of the car; there are at least two on which this braking system has been adopted, and there may be others. The tyres had identical treads; that is, practically plain rubber, and the car was fitted with an ordinary type of differential gear. It should be said, however, that the ear has a rather long tvheelbase in proportion to track, and is not, in the ordinary way, prone to skid. It was a four-seater, with the rear seats empty. I approached the tests with an open frame of mind, and I must say that

after going through the experiences, which I shall presently, relate, I am inclined to be in favor of the arrangement. These were the tests:—The car was speeded up until 45 m.p.h. was registered and we were proceeding down n gentle slope with a slight bend to the left, when the driver piilled-»the offside rear brake on hard- The car pulled up very suddenly, travelling iu a almost straight line. The locked wheel left a skid mark on the road, and it was almost straight for approximately 45 yards. This mark was clean, and showed no indication of skidding. The test was made again, this time on a straight level road, and the foot brake was operated on the near-side wheel. The car pulled up in a rather shorter distance, and left a skid mark which was quite straight. Then tests were made with the driver leaving the steering wheel free from the moment the brake was applied until the car came to a standstill again. The car ran perfectly straight, except that in the last few yards, when it was nearly stopping, it pulled in to one sido of the road for a distance of about a fodt. Then both brakes were applied simultaneously, and I almost shot through the windscreen, the car pulling up dead in 25 yards. Then the driver tried a rather nerve-racking stunt when the car was travelling at its maximum speed, for, as he applied the. brakes, he turned the steering wheel first one way then another, demonstrating that he could drive the ear in any direction he liked whilS only one wheel was locked. The result gave no cause for anxiety. The locked wheel left a snaky track from, one side of the road to the other, following the steering wheels precisely. At the bends of the skid mark the edges were clean and sharp, with not a trace of skidding, yet one would have expected the car to have turned completely round. In all tests the engine was declutched, so. I induced the driver to make another test, .en.ying the clutch in. With an ordinary differential gear this has the effect of increasing the gear of the wheel that is driving; again, the results were no different from the foregoing. 'lt seemed impossible to make this car skid, even with one wheel driving and the other one braking. It is worth remembering that a parallel case is that of the sidecar, where the brake operates on the single driving wheel, yet it is notorious that the motor-cycle and side-ear combination does not skid; in fact, it is the most, immune type of motor vehicle- Since these tests were made, I have been wondering if we have not baen accepting a practice which dates back from early motoring days without scientific Investigation. Supposing the drive from the engine to the back axle were freed, is there any reason why the car should skid because only one wheel is locked? Furthermore, if the brakes are compensated accurately, do they remain so for any length of time? My experience is most decidedly that they do not, and even if their action is simultaneous, would not that be negatived by variations in road surfaces: with which the offsidp and the near-side wheels are in contact, and in the treads of the tyres? The more I think about this idea the more convinced I feel that we have been following a fallacy." Sir Ross Smith au(d party's great flight on the Vickers Vimy from Melbourne to Adelaide, about 400 miles in a direct line, in o 2-3 hours, serves in a way to emphasise what a remarkable drive Murray Aunger put up over the inter-State route between those two capitals. Aunger on his Dunlop-shod "Vauxhall" covered a distance of 594 miles by the route he took and had bad roads and the sand drifts in the Coorong to negotiate, yet drove from Melbourne to Adelaide in 14 hours 54 minutes. It was a wonderful performance and one destined to stand undisturbed for many a year.

The arrangements are already in hand fpr the Indianapolis "500," the longest motor ear track race in the world. The conditions of this premier American speed event luive been framed so that the weight of ears and capacity of engines will conform with those that are to be adopted for the next French Grand Prize Road Contest —this evidently with a view of attracting the fastest cars from Europe for the coming event. The total prize nwnev for the Indianapolis contest is £IO,OOO, of which £4OOO goes to the winner. In addition there are, a number of other valuable prizes donated by various American accessories and tyre manufacturers, which brings the victor's cheque up to close en £6OOO, The event is to be decided on May 31. A'Preneh car in the Puegeot carried off the last two events.

A novel bicycle created a stir at the recent siv-days bicycle race held in New York, when the inventor gave an exhibition ride on the steeply banked traek. The machine only has wheels, pneumatic shod, about the size of a small dinner plate, but vertically it is not dwarfed, for the rider sat, or virtually stood upright, in contrast to the average cyclist who leans forward on to the handle bars. The machine was designed for use in city streets, and is a most compact contraption. Length of wheel base less than three feet, the drive being taken from a large sprocket attached to crank axle and pedals thence direct to the miniature driving wheel. The sprocket is set above the two road wheels, the whole forming a triangle of wheels- The inventor's idea is that owing to the machine being so small and light it can be taken easily into buildings l , etc., instead of having to be left at the kerb side, inviting theft. A pace of 20 miles an hour is said to be attainable on this miniature cycle. One of the most unsatisfactory details of modern cars is the undershielding- There are few examples of really eflicient undershields whicli can be readily taken down without a great deal cf trouble and discomfort. Struggling with an undershield is about the most temper-provokiug job about a car. The fitting of easily screwed up or unscrewed elamps which will hold the shield firm and free from rattle seems to be more of a problem than one would at first sight expect it to 'be. The fittings, being exposed to wet and dirt, soon get rusty, and it is quite usual to find hand screws or mits which have permanently rusted on to their bolts or studs. The spring clips which are sometimes fitted soon get loose. The springs, through reduction of the metal by rust, get weak and elongated, and the shield hangs down and rattles and admits dirt and wot. Often the springs break and let the whole shield down on to the road with a terrifying noise. A driver has even been known to come home without any nndei--liicld and without knowing that he had lost, it. If an undershield could be made of cast aluminium and could be pushed' along in a slide, each side of the frame underneath it would be easily detached in use. One bolt and nut in front could hold it, and the job could be dine without. hr.virg to. crawl unde.' the ear. i t seems a poin t to which designers might give some attention. An Australian engineer well versed in automobile engine practice, recently retiirned from a visit to America, where i ftp siateo ilia: he luu an opportunity of

examining and seeing tested a remarkabl'; etlicieut new type of sleeve valve automobile engine. Unlike the Knight valve power unit with its reciprocating two sets of sleeves per cylinder, the new type engine known as Hie "Americ.ui sleeve valve engine," differs very considerably from anything yet seen in this type, of power unit. For years automobile engineers in all fields have sought the ideal engine. There has been prolonged search after the right combination of cylinder type, valve size, shape and method of operation, reduction of Working parts, etc., with but partial success. T e two-cycle engine has not realised anticipation from an automobile viewpoint, whilst the Kmight engine, although giving very satisfactory results, does not reach the ideal, and leaves room for improvement.

The "American" engine by actual laboratory and road (cats of both a theoretical and practical nature, have proven beyond doubt that this unit is sometliing exceptional. In this engine a single rotating sleeve driven by spiral gear is used, resulting in perfect balance and a wonderfully efficient motor. In this unit from 25 to 50 parts are eliminated, resulting in increasing simplicity. The engine is of the 4-cylinder type, 4in. bore and Sin. stroke, weight 5811ba. In 2100 revolutions it develops 50 h.p., and 00 h.p. at 2200 revolutions. The latter figures work out at 0.71b. weight per h.p. developed, a remarkably low figure for a commercial everyday automobile power unit. Fitted to a ear weighing 27G01bs, giving a ratio of oue horse power to ejeh 461b of car weight it accelerated from a standing start to over 20 miles an hour within 100 feet. It climbed stiff gradients on the top gear, that far more powerful cars have to take on the second gear. A remarkable feature is that tin torque, or twisting action of the engine, is the same at all speeds of the motor.

The smoothness of running was illustrated by the fallowing demonstration. The power unit was rested on three wooden supports laid on a testing bench, no bolting down being done. The engine ! was fun at varying speeds without tiie semblance of vibration, in fact a wooden peg. stood erect on top of the engien when , running at high speed. Such steadiness is remarkable. The designer of this power unit has evidently evolved something out of the ordinnry, and if lit lives up to its promise (it has had two years' test on the roads) its inftiiI ence on Automobile engine design will be | marked.

The general run of tool kits which arc sent out with .motor vehicles are a delusion and a snare. Particularly is this the case with some makers. We have seen a kit of tools in a leather roll, no one of which would be tolerated in the workshop even of the amateur. In view of the big price paid for cars, and considering how bad tools spoil good work, it seems a very penny wise and pound foolish policy on the part of the make, not. to spend a little more money and give users a batch of really high-grade tools with which to make the necessary adjustments and running repairs. "A good workman never complains of his tools' is an old saying. But a good workman never tolerates bad tools.

It is interesting to note that the tourspeed gearbox is being considered hoim seriously by Knglish designers of light cars. It l)as 'been said frequently that since economy is the object of the light car, then a fourth speed should liot be thought of because it only increases cost. Those that have had experience of four speed cars will contend that the point of economy is the very reason why it should have consideration. A four-speed car should be more economical to run than a three-speeder. The main part of one'* running may be said to be on the level or on a slight down grade, when a moderately high gear can be used and the engine run slowly. It would be a mistake to add another lower gear when the average car will climb most main road hills on second. It ia an extra high gear that is required, and if this was to be a ratio intended solely for very favorable conditions, then, of course, the dic'jct would be the third and the extra high gear would be through gears. It is possible to have both the third and foirtli equally direct.

(Juite mystifying effects may follow the use of petrol in which dirt or other foreign substance occurs. In the first place, the petrol strainer in the pipe line may be partially choked and cause insufficient fuel to reach' the carburettor when the engine is running at high speed. The symptom in such a case is often a total cessation of firing when an endeavor is made to accelerate the engine, as, for ins'tnace, when a lower speed is engaged to rush a hill. The strainer may, however, become entirely choked if it has a fine-mesh gauze, when, obviously, the engine will fail to run at all. There is, however, nothing mysterious about this. But there is often troubla in locating the defect when one or two isolated particles of grit manage to find their way to the bases of the jets. A solitary -cause of obstruction may cause a most peculiar intermittent misfire. A piece of grit at the bottom of the jet may only occasionally be drawn up into the restricted orifice. In the case of a multiple-jet carburettor, tliis will reduce the richness of the mixture nnd'eause a peculiar hesitancy on the part of the engine when the throttle is opened. Or, if the obstruction be in the starting jet, the engine may run quite normally in all throttle positions except that suited to slow running. . The engine will then cut right out. "In other words, it refuses to run slowly. The writer has known occasions on which such solitary particles of grit have necessitated a long investigation before the cause of the trouble was found. The reason has been that when the carburettor has been detached for an inspection, the fuel has drained oft and the grit has run back into the body of the carburettor, where it has remained out of sight. It may have receded only round the corner, as it were, at the point where the restricted orifice of the jet opens out .into the larger diameter of the main bore. In playing "hide and seek" in .his way, r, solitary particle may, therefore, give rise to what is seemingly a most mysterious fault. Tlie symptoms may bo equally applicable to'such causes as a faulty plug, a badly adjusted magneto, a shorting high-tension wire, a sticking valve, and other similar troubles, above and beyond a restricted fuel supply through one of the jets. It will surprise most motorists to learn that when the armistice was.signed the British army had "tanks" in operation. Few people in this part of Hie world ever realised to what an extent this new war-chariot was used. Most of tin: fleet are having tlw* engines re-, moved, the remains being scrapped.