MOTORING & MOTORISTS

Evening Star, Issue 21080, 18 April 1932, Page 13

MOTORING & MOTORISTS

LIGHTING-UP TIMES. To-day ... 5.50 Tuesday ... ... 5.57 Wednesday ... 5.55 Thursday 5.53 Friday .' 5.51 Saturday 5.40 Sunday ••• 5.47, THE ELECTRICAL SIDE. ’A FEW FACTS FOR THE OWNER. The motorist who does, not understand electrical apparatus will, no doubt, bo relieved to learn that there are few parts in the equipment of a car likely to give trouble. A few facts about the starting and lighting set may bo helpful in the care of these components. Starters and dynamoes are similar in construction and are essentially simple .units. They have only one rotating part, and nothing that could strictly be called mechanism, no moving lovers, gears or cams. The dynamo armature runs on ball bearings, which only require infrequent lubrication. The reliability of these electrical units is such that the great majority of .car owners give them hardly any attention so long as they keep on working satisfactorily. The dynamo commutator should be cleaned, say, once in 6,000 miles by detaching the circular protection band at one end of the dynamo and pressing a piece of clean, soft rag on the commutator while the dynamo is running slowly, the engine being throttled down to idling speed. This cleaning removes any carbon dust which may tend to lodge between the commutator segments. The novice should not try altering or experimenting with the brush gear. Ho will probably learn as he gains experience that there is a control brush which is adjustable, so as to regulate the output of current, but it must be kept in mind that this adjustment is originally fixed by the manufacturers. The general condition of the dynamo, so far as generating its full output is concerned, can bo gauged from the ammeter readings. The system of controlling the output ensures that it will not increase when a certain speed of the cas is attained; that is, usually, 25-30 miles an hour. Beyond this speed the ammeter-charge reading will remain steady, or it may even go back to a small extent. Any falling-off of dynamo output means that a discharge is being taken from the battery, whereas there should be a small reading on the ■“ charge ” side of the ammeter when all lights are in use. As regards the starter, the brushes and commutator of this component of the car undergo very little wear, owing to the very short period of intermittent running. The circular protection band is usually detachable, and the commutator can be cleaned in the same way as that of the dynamo when it requires it. An electrical fact that should be always kept in mind is that it is the battery that supplies the store of energy for starting, and that the starter is only a convenient means of utilising that energy. The battery should always be kept up to its maximum voltage and in a condition to supply the sudden rush of power required to turn the engine. A half-discharged battery, although it will “ work ” the lights, will not necessarily “ work ” the starter when the starting conditions are unfavourable. It is rarely that there is any electrical fault in the starter if it fails to do its work. It is nearly always the case that the battery is not fully charged. FREE-WHEELING. One of the leading innovations on many makes of cars this year is freewheeling. In the free wheel there is scope not only for improving economy of running, but also for making expensive driving errors. Every well-designed free wheel incorporates a device for putting it out of operation, and unless this is used correctly, the free wheel is likely to prove ultimately an expensive luxury. The free wheel serves two purposes—it provides coasting without the necessity for putting the gears in neutral, and it simplifies gear changing for that large body of motorists who have never learnt to change gears with certainty. The advantages of coasting are a saving in fuel and oil consumption, with a reduction in the rate at which carbon deposit is formed in the engine. On the debit side of the free wheels is undoubtedly the extra use of the brakes which it makes necessary. Since the inception of motoring, one of the distinguishing marks of a good driver has been the degree to which ho substitutes the drag of an idle engine for direct braking. While brakes have been vastly improved, especially in cheap cars, within the last few years, the engine is still the only brake which cannot be overheated or worn out by prolonged application.

[BY RADIATOR.]

Brie! accounts of holiday trips, roads, and places of invited for this column.

No good driver would attempt to coast a long grade, steep and obscured enough to require constant checking of the car’s speed, and poor drivers seldom do much coasting in neutral, since they may experience difficulty in picking up the gears again. Even if excesses in its use arc avoided the free wheel must throw extra work on to tho braking system. This means that the owner of a car so equipped must devote extra care to. beeping the brakes in really good order if he is to maintain tho ordinary standard of safety. Relining will bo needed at more frequent intervals, as well as adjustment. Rules for tho use of a free wheel, therefore, are: Do not use it on hills where speed must be controlled, or in circumstances where tho application of brakes to reduce speed may be dangerous, such as on slippery roads. Neither should it be used if the brakes are faulty, as the extra braking from the engine may then be necessary to avoid an accident. A piece of advice for those whoso cars are not fitted with free wheels is not to try to obtain free-wheel advantages by holding out the clutch for coasting. This soon causes wear of thrust and pilot bearings which arc expensive to replace. The only way to coast without a free wheel is to put the gears in neutral, and to pick them up .".gam when power is needed by accelerating the engine with the clutch engaged, declutching just as the gears are to be meshed. REVOLUTION counter. MOST USEFUL DEVICE. The ordinary motor car is never equipped witli a revolution counter, but has a speedometer instead, whilst on the other hand a racing car has a revolution counter and no speedometer. Never is the ordinary car engine designed or tuned for very high revolutions, and tho speedometer is sufficient to tell the diver his approximate speed. In racing machines where the motor has a safe maximum limit of, say, 5,000 revolutions per minute, care must be taken that the motor does not exceed this maximum in neutral or in any gears since irreparable damage will probably be caused to the motor itself. The rev.-counter, coupled direct to the motor, is a positive guide for tho driver. Also, in racing, quick gearchanging is essential, and often those changes must be executed at high speeds. Here the rev.-counter conies into use: the driver knows that when he changes from top to third gear he will require the motor to bo turning over at one-third more revolutions per minute since the gear ratios are, say, top 3:1, and the third gear 4:1. Before changing down he notices that the rev.-counter shows that the motor is running at, say, 2,100 revolutions per minute. Then lie slips the gear into neutral and revs, the motor up until it is revolving at 2,800 revolutions per minute, when he can immediately effect a silent change into third gear, and thus eliminate all guesswork and delay in changing. Without a rev.-counter such precision work would be impossible. However, in a lower gear the maximum revolutions can be exceeded very easily, and unless the driver beeps his eye on the rev.-counter he may find that his motor is turning over at a speed that greatly exceeds the safe maximum for which the motor is designed. Similarly on an ordinary car, especially one with a silent third gear and “ snappy ” acceleration, the motor is frequently revolving at a speed which is far in excess of the safe limit. The speedometer is no guide to engine speed. The driver, his car flat out in second gear or silent third, has no way of determining the number of revolutions at which his motor is turning over, or if he is exceeding tho safe limit for tho motor, and usually he changes up when vibration and valve clatter sets in or when his speed reaches its maximum in that gear. Over revolving is far too common a practice nowadays, and is a direct cause of heavy oil and fuel consumption and rapid cylinder wear. Every motor has a peak period when the maximum horse-power is developed at a certain number cf revolutions per minute, beyond which the po ver developed shows gradual decrease and the bearing loads rapidly increase. Tho manufacturers generally state the revolutions or speed should never exceed a certain figure, and this applies more especially to the lower gears. Here is a simple formula by which tho miles per hour as shown by the speedometer can be readily changed into revolutions per minute whether top or a lower gear is engaged: 33G x G x S - Where 336 is a constant; G equals gear ratio; S equals speed in miles per hour; and T equals tyre diameter. LIGHT SCREWS. Screws which refuse to “ start ” owing to rust or to their having been done up extra tightly may sometimes be freed readily by a very simple method. The screwdriver, which should have a properly ground blade, is engaged with the slot in tho ordinary way, and, whilst a steady turning effort is applied by means of _ tho left hand, several sharp taps are given to the end of tho handle with a hammer. For this purpose a screwdriver of the type having a metal handle with wooden cheeks must bo used, as, apart from the risk of splitting an ordinary wooden handle, the power of the hammo- ’ blows is absorbed by tho wood instead of being transmitted as a series of sharp impacts to tho screw. IMPROVISED LIGHT. When making adjustments beneath a motor car difficulty is often experienced through lack of proper illumination of the parts concerned if no portable lamp is available. This difficulty can be easily overcome by tho employment of a frame mirror about 12in by 9in. The mirror is placed on the ground beside the car, so that the light, either from the sun (if it be daytime and the car is in the open) or from some strong source of artificial light, falls directly on to it. Tho mirror must then bo adjusted by means of hi ks, so that it reflect, the light l-.ieath tho car on to the part requiring illumination. Generally, unless the repair job is a short one, it will be found more convenient to use an artificial source of light than to rely on the sun, because, although the light from the sun will he stronger,

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it will move quickly off tho part on to which the reflected light is directed, and frequent adjustments to the mirror will bo necessary. In an emergency the same principle can be used at night for making inspections beneath the bonnet by placing the mirror, which may bo of the handbag type, in the light from tho head or parking lights and reflecting the “ spot ” on to tho mechanism. NEWSPAPER FOR CLEANING. The fact that a crumpled sheet of newspaper is one of the best means of cleaning tho windows and windscreen of a car is fairly widely known. But very few owner-drivers realise that newspaper is an excellent moans of cleaning tho oily parts of an engine; it absorbs the oil and picks up tho grime more readily than many kinds of cleaning rags. Moreover, it enables the latter to ho economised and kept for finishing off the cleaning process. Bags are generally more difficult to obtain than newspaper. THE USEFUL MAGNET. In dismanting and assembling many parts of motor car mechanism tew mishaps cause greater loss of time or inconvenience than the accidental dropping of small nuts and bolts into places where they cannot bo reached by tho fingers, hi cases such as this a powerfid magnet provides a speedy method of recovering all parts made of iron and steel, and it can also bo used for holding smiill bolts into inaccessible holes until tho first turn, which grips the threads, is applied. In tho absence of an ordinary permanent magnet, an electro-magnet can easily be made up and kept as a garage tool by winding a few ounces of medium gauge cotton covered copper wire in a series of layers over a soft iron bar. This bar can bo fitted with a wooden handle to facilitate its handling. The ends of tho wires can be attached to a length of flexible cord, which, terminating in a plug, may bo placed in the inspection lamp plug for the excitation of tho magnet from the car battery when it is desired to use it. TREAT THE STARTER GENTLY, When a battery is charged or discharged very quickly it will overheat and the overheating may result in the plates warping. Wlien the plates warp the paste will fall out of tho grids. Not only will this prevent the batter from taking a charge, but it will short-cir-cuit the plates at tho bottom. Using the starter motor for a considerable time at a stretch means a quick discharging of tho battery and a possible .overheating and warping. Therefore, if the engine refuses to fire, do not use the starter for a long time, but get out and find out why the engine does not start. LIGHT WIRE USED. STOPPING MOTOR BANDITS. Developed primarily for Army use Great Britain has found an effective road barrier for stopping fleeing motor bandits in nothing more substantial than a roll of light wire. The wire coils, about four feet in diameter, weighing less than 501 b, and stretching about 60ft, were found to block roads so swiftly that armoured cars and trucks were stopped dead in their tracks. The roll of wire is known as a “ fence concertina,” and is stretched across tho road at a point where it is desired to stop a car. The secret of its efficiency lies in its ability to tangle. When a car runs through it the coil stretches and then breaks, the loose strands twisting about tho wheels, winding into the steering gear, working into brake drums and around axles, and usually finishing the job by completely jamming the engine. NEW PATENT SPRING. LUBRICATION GROOVE. It has often been suggested that, by using spring leaves of special section, channels could ho formed through which grease could bo distributed from a central nipple supplied at intervals from a gun, but so far this method has _ made but little practical progress. It is therefore interesting to notice that an entirely new spring of this kind has been brought out by a famous British firm of spring makers. Although, at present, the idea has been applied only to certain heavy commercial vehicles, there is no reason why it should not be adopted for cars. Tho patented section used for tho plates lias the advantage of locking each plate to its neighbours in respect of lateral movement, although tho usual endwise sliding can take place quite freely. The plates arc, therefore, positively prevented from splaying. Tho special feature of the section is, however, found in the longitudinal channel left between adjacent plates, through which grease can travel from a centre bolt of grooved design fitted with a nipple for the application of the usual gun. An incidental advantage of tjiis patented section is that it enables maximum working stresses, somewhat higher than those normally employed, to be used with safety. In other words, springs built up of plates with the section need not bo so heavy as a normal spring of tho same length and taking tho same load. Tho reasons underlying this property relate to tho fact that, when the curvature of the plates is altered (by loading), each plate tends also to curve laterally, becoming slightly convex on tho compression side and concave on tho tension side. USE FOR EXHAUST GAS. Using tho exhaust gas of motor cars to clean the upholstery is the accomplishment of a recently invented device. An aluminium attachment is fastened to the exhaust pipe and the engine is allowed to run. As the exhaust gas passes through this device •suction is created at the inlet hole. Collected by a nozzle tho dust and dirt are drawn through tho hose and expelled into the air at the rear of tho car.

MOTOR CYCLING FIXTURES. April 30.—Gymkhana. May 7. —Treasure hunt. May 17. —Monthly meeting. May 21.—Club run. -Juno I.—Trial. June 18. —Sporting trial. Juno 21.—Monthly meeting. THE LO3AL CLUB. The monthly meeting of the O.M.C. motor cycle section at the club rooms to-morrow night promises to be unusually interesting. Though everyone is most secretive it is understood that some reminiscences of Wanaka have been prepared in verse form. Our worthy champion will give an account of his adventures while crossing the Cardromi. Last week-end a small party of club members made a trip to Caberfeidh, which was thoroughly enjoyed, even if the weather conditions were not of the best. The return journey was made in Sunday’s heavy rain, and in spite of towels wrapped round one’s neck the water managed to trickle in. and add to the discomfort. In four or five places small torrents were rushing across the road, but there were no stoppages, and when everybody was home and dry it didn’t seem such a bad trip after all. GOOD HABITS. The control of a motor cycle, once one has passed a very elementary stage of proficiency, is automatic. In emergencies, that is to say, when there is no time for thought, one docs the right thing without thinking about it, and in the ordinary way if one’s mind is occupied with other matters one can make a long journey without ever really thinking about the machine at all. There is no sort of doubt about this. The experienced driver, who has just got himself out of an awkward situation by the superb handling of his model, can very seldom tell you exactly what ho has done. Since wo control our machines by habit (and particularly at difficult moments) it is obvious as well that the habits that wo form should be good.