MOTORS & MOTORING

Dominion, Volume 9, Issue 2752, 22 April 1916, Page 15

MOTORS & MOTORING

_ —. —< IBT CiiUTOH.I Petrol Economy. In roferenco to the subject of petrel economy, the results of some scientific experiments carried out by the engineering department of tho National Physical Laboratory '(England) may be interesting. The object of the testa was to discover what effect the filling of oil to different depths liad oh the efficiency of a gearbox. A standard Leyland .gearbox was used, and top gear throughout. When the gearbox ivas quarter full the efficiency was 974 per cent., when halffull it fell to 04 per cent., when threequarters full to per cent.,, and when full it fell to 74 per cent., a loss of 26 per cent. What the efficiency would lo if a gearbox were filled with stiff grease is left to the imagination. In racing cars generally just enough pure castor, oil is the gearbox and differential to insure an "oily atmosphere"— the lower gears dip into the. oilj and, by their high speed, spray it all through the' box. Another cause of petrol wastage is a small but ever-activo loak, often so small thai the petrol evaporates as fast as it comes out/ so that 'moisture may not be noticeable at the petrol pipe union to tank, the drain cock (or plug), or the shut-off cock. Although euoh a leak may not be noticeable to the eye, as petrol evaporates so quickly, it is possible for it to pass quite a lot of petrol in twelve months. If suspicious that petrol is getting away when the car is not in, use, try if petrol can be detected by smelling. The cure is obvious—a good fibre washer and tightening up for plugs and grinding in for cocks. A Useful Toolbox. Unless the car is really well provided with storage space, tne motorist is advised.to fit a boy of this kind! under the driving seat, and finds'it most,useful for carrying the emergency parts and spare air tubes. Two bars were fitted across the chassis, - the running board bracket bolts being made use of to secure them, and the box suspended by suitable "ingle" irons from these bars. Dimensions of. the box are 1 roughly 18in. by 10in., with a depthsof about 12in. There is a central tray in the box, the lowest compartment being used for carrying' such spares as reserve valve, magneto parts, bolts and nuts, ■ etc. Three spare tubes, each one packed separe carried in. the upper compartment of the box._ To reach, the tubes it is necessary to lift up a trap door, which has bean' formed in the floor of the car, directly under the seat. It is becoming more common to fit a reserve box of this nature on modern cars, but where this work lias not been done by the maker it can be undertaken by the owner, or done by a carpenter at very little cost. Naturally the best position for the box varies aocording to the design of the chassis. It is not advisable to place it too near tho exha,ust box, and it should .he seen that it is not in danger of swinging so as to touch any moving part. , . K Reduced Lighting and London' Street 'Accidents. - ' j Mr. Herbert Samuel has given the following comparative official figures of fatal accidents in London:— . 1013, 1914 1915 Motor-buses ' 190 156 156 Electric tram-cars ... 68 S7 87 Motor-cabs 30 61 66 Private motor-carß ... 83 119 191 Motor-rcycles 13" 23 28 Trade and commercial : v motors 61 112 150 It will be noted that the increase of fatalities with electric tram-cars has gone up by more tlian 130 per cent, for 1916 against 1914. Why Oil Leaks. To find oil oozing out of bearings which are known to be quite sound mechanically is rather annoying. If the engine is hidden from view it may pass unnoticed for some time; but one of two things must .happen—either'the oil bill must go up or the engine go short. '/Some engines leak at soveral points, and the -loss from the bearings goes to make up tho general mess, and is suffered because the engine has achieved the reputation ,of being "dirty.". | There is one reason for leaky bearings, says a motoring correspondent, 1 which I have, never seen in.print, and I have only met one motorist who has ,tioned it, and that was nearly ten years, 'ago. Before detailing it, 1 would say I do .not consider it an absolute: fault without any redeeming'featura. I would also add that, although I do not con-sider-the four-cylinder exempt from these remarks, it is. the twin V engine that I have observed'most' particularly. Most engines of this type, having brass bearings* take the end play or thrust on the plain surfaces formed by, the ends of the bushes I and the shoulder formed on the shaft or the boss of tho flywheel. An examination of these parts will shbw how "highly polished they becomo and "ground" to a very close fit. Obviously they are well lubricated so long as there is any oil in the crankcase, and this will be subjected to no mean pressure, especially if the;belt of chain is out of line. In any case, there s a rapid oscillation of the crankshaft, whicK puts the film of oil on the thrust surfaces under pressure .as the shaft and flywheels are checked whilst moving from one side to the other. It so happens that, whilst some of the oil is engaged keeping the surfaces apart, the surplus is finding the line of least lesistance. If the thrust surfaces are - examined, a mim ; - ber of rings will be noticed. These rings are more or less a series of grooves and ridges, the ridge on one surface fitting into the grooves of the other. Some are more definitely marked than others, but the finest offer considerable resistance to t.he passage of the oil as it is squeezed out from between the surfaces, and thus the pressure on it goes up. Tho movement of the shaft causes the bearing to scrape the oil 'off it and pile it up in the angle formed b,y the boss on the flywheel, and any oil that happens to he trapped here -will be forced into and through the bearing. It is not difficult to see these surfaces, together with movement of tho shaft and flywheels, constitute something akin to a pump.

I have 6aid I do not consider it solely an evil, 'and it is for this reason: we know t that certain manufacturers endeavour to create a vacuum in the orankcase, partly because if the' pressure in the crankcase becomes greater than that of the atmosphere, the oil will be forced through any bearing or joint that' l offers it an opportunity of Duress. On the other hand, if the air pressure in the crankcase is less thai that of the atmosphere, air will be drawn in via tho bearings, carrying with it the oil in the bearings, and so starving them; remembering there is air not oil.drawn in. (This is obvious, as the oil "cannot be made . to flow against a greater pressure than that acting on it, i.e., the pressure in tho crankcase.)' I am e of the, opinion that, were it not for . the pumping action mentioned above, {ho bearings would be starved. Here anil There. Lighting up time J'or motor-cars and motor-cycles: To-day, 5.14 p.m. Next Friday, 5.4 p.m. Ah aluminium /famine is feared m tho States, and many manufacturers thpro are already returning to the use of castiron for crank-oases and other parts on account ol : the high price ol , the. material, which lias now reached half a crown a pound. Tyre prices, too, are increasing in America, owing to' the scarcity of rubber, and advances of from 12jj- per cent, to 20 per cent, are being, announced. , ' ■ If a tyre has to be obttnged • aJter

long and uninterrupted service, it frequently happens that the greatest difficulty is experienced in finding a placo where the lever can be inserted. Instead of looking round ior a and a heavy hammer, tho hotter plan is to lower tho wheel to the ground ond rim the car for a. distance of -0 yards—not moro. This will have tho olfect of loosoning the head from the riii and allowing tho tyre lever to be inserted without difficulty. It is quite a. common occurrence with a tyro which has not been disturbed for __several months for the bead to become almost welded to tho rim, there is no actual rust formation. No iiiirni will bo done to the tube if the car is run on the rim iu the short distance mentioned above. The 'difficulties in the way of the transport of goods from America seem to be greater than, ever, • and tho prices charged are enormous. It is reported that a sailing vessel has been enjgaged by a United States firili of motor-car manufacturers to carry 2000 cars from New York to Sydney. A four-masted sailing ship was secured for the purpose. A year ago it was towed into an | American port as a wreck and sold for £6000. The owners of the ship are being paid £8000 for the journey. The Swiss Government have now decided to adopt two types of subsidory lorries only—a two-ton lory for service in the mountainous districts and a fiveton lorry for ordinary roads —war conditions have been carefully watohed. One of the leading English motor sparking-plug has just erected a plant that will be able to p'ut out 10,000,000 plugs annually. This is only one,concern, and conveys an idea of the tremendous growth of the motor industry during the last decade. The English war authorities recently permitted representatives of the leadjng English ' motor-cycle concerns to visit the front in France, with a view to observing' the condition under which their machines are used, and of con-j stilting the riders as to how the ma/ chines are standing the wear and tear of the, work of the war. The oxperienoo gained from these visits .Bnould prove invaluable to the manufacturers, for which the British-made motor cycles are doing wonderful work in the fighting zone. It is. only to be expected that the severe war service will bring to light 'weaknesses and little details that need attention. Later on motorcyclists will derive the benefits of tlie strenuous trial English machines arb now undergoing in France. The rise in the price< of benzine is troubling motorists, but if a "speedier" is attached to the machine or "car, the cost of benzine, it is claimed, becomes cheaper than ever. R. Miller, Platform, Greytown, in an attractive advertisement appearing in' this issue, points out that by procuring a "speedier" attachment less benzine will he used, and a greater speed attained. Tlie prices are:—Car size 255., niotor-cycle 15s. A thirty days trial is allowed with the "speedier, and a refund of cash is made if this economic device is not satisfactory'.-