MOTORDOM

Greymouth Evening Star, 31 August 1934, Page 4

MOTORDOM

NEWS OF THE ROAD

(By “Gearbox” )

LIFE LICENSE FOR 25/-

For a total payment of 25/- the motorist in Johannesburg- obtains a driving license for duration of life —but he or she must first qualify for it. A prospective driver applies to the licensing officer, producing two photographs of passport size, and pays 5/for a temporary permit. An. appointment for a driving test is then booked. The test, which costs 10/-, takes the form of a practical demonstration of driving ability through the city streets with an examiner as passenger. The car bears a placard fore and aft, with the words: “Caution! Driver on Test.” Then follows an oral examination covering such things as traffic laws, signalling and knowledge of local parking arrangements. Thereafter, having satisfied the examiner, the driver part£ with another 10/-, to receive in exchange his driving license. Of the 4070 prospective drivers examined by the Johannesburg inspectors last year 755 were women. About 10 per cent, of the men and 26 per cent, of the women failed to pass the tests. Indecision is stated to be the chief cause of failure among the women applicants. CORROSION OF TERMINALS Creeping and seepage of the battery solution on to the terminals and the thimbles of the battery cables is a frequent source of trouble, and one which can only be avoided by inspecting the cells regularly, cleaning the parts, and keeping them well smeared with vaseline. if that is not done, corrosion takes place, a high electrical resistance is set up between the plugs and the cable connectors, and it may be found that although the cells are well charged the starter-motor will not turn the engine, but when the switch is closed there is a sizzling noise at the terminals. Sometimes that might be due to a loose contact, even when the thimble and terminal are quite clean, and whenever the accumulator seems to have gone suddenly “flat” for no good reason, the first step should be to examine the connections, tightening or detaching and cleaning them, as may be necessary. . \

THE COOLING SYSTEM Probably the most neglected part of a motor-car is the cooling system, which, however, has an important influence on engine efficiency. Except for an occasional topping up, most motorists seldom give a thought to it unless continual boiling occurs. Deposits caused by corrosion in the system can cause a marked loss of power and increase in oil consumption. It is important, therefore, to prevent corrosion to the greatest degree possible and to allow the cooling water to circulate freely. Deposits and corrosion can be prevented by the use of cheap chemicals. In districts where the presence of lime has hardened the water supply, trisodium phosphate should be added in the proportion of 5 oz. to each 100 gallons. Where the water is soft, but still corrosive, soda ash can be added at the rate of 2oz to each 100 gallons. Before using either of these mixtures, the cooling system should be flushed out. It should then be filled with the mixture, and drained off in about a month’s time to remove the small quantity of sediment which will have been formed. The mixture should also be used for topping up the radiator. When an old engine is badly corroded, slightly greater proportions can be used for a. time to dissipate existing deposits.

GRAPHITED OILS. VALUE FOR RUNNING-IN There is an increasing number of oils and greases on the market containing colloidal graphite. This material is so finely divided that it will pass readily through oil-ways and filters. When carried by the oil through the various bearings the graphite particles form what is called a “graphoid” surface on the metals, thus tending to smooth out the irregularities and to provide a greasy film over which oil spreads very readily. It has been proved by careful tests that, such a film is an excellent safeguard against bearing seizure should the supply of lubricant fail temporarily, as when starting a stiff engine on a cold morning.

Graphited oils are of particular value when “running in” a new or reconditioned chassis. Although smooth to the eye, the surfaces of freshly machined shafts, bearings, pistons, etc., present microscopic irregularities and, when pressed into contact, produce very high pressures over the high spots, which are prejudicial to the maintenance of a lubricating film. The exceedingly tiny graphite particles in the oil improve lubricating conditions during the process of breaking down these irregularities, and probably also tend to fill in the microscopic valleys which separate the high points. That this action is no mere theory has been proved by various scientific tests, and oils containing collqidal graphite are now being employed during the assembly of engines by many car manufacturers. They are equally valuable in the case of a reconditioned engine, which, of course, must be rim in in much the same way as a new engine.

While the surfaces are still rough—if one may use the term to describe such minute irregularities—the amount of heat which is generated is abnormal, so that if the car be overdriven there is risk of the oil film breaking down, followed by metal-to-metal contact and material damage. Here again -the use of colloidal graphite forms a safeguard, because it has been proved that under conditions of scanty lubrication a graphoid surface will provide sufficient greasiness to prevent seizure for quite a long period.

Running-in compounds, consistingof oil carrying colloidal graphite, can be obtained for addition to the lubricant in the sump. Preferably, the oil carrying the graphite should be of a kind similar to that used normally in the engine. Thus, with few exceptions, the running-in compound is a straight mineral oil and will give the best results when mixed with a similar “straight” lubricant.

A new engine can be overloaded both by excessive speed and by too free use of the throttle. Both these faults should be avoided by the driver/ but. on the other hand, if lie is too kind to the mechanism he will prolong the running-in period to an undue ex-j tent. The great point to remember is] that it is excessive temperatures which result in harm; thus, while a short

burst at full speed will cause no damage. and will, indeed, engine, a prolonged run at full throttle may easily result in seizure or bearing failure. . , Upp&r cylinder lubricants mixed with the fuel are being used by many thousands of motorists, and niost o. these contain a proportion of colloidal graphite. In a desire to limit oil consumption many designers have resorted to the use of very stiff piston rings, with the result that piston lubrication is often inadequate. Furthermore, very little oil reaches the bores during the first few minutes after a cold start. Consequently, there is much to be said for the idea of introducing a lubricant with the fuel, although the quantities which can be used are necessarily small. An excess of lubricant would, of course, tend to give trouble with sparking plugs and carbon deposits. Colloidal graphite is particularly suitable for cylinder lubrication, owing to its resistance to heat, its affinity for oil, and its ability to form a film over metal surfaces. In some cases it is also found to have a beneficial effect in keeping the valves working freely. Oils containing colloidal graphite can also be employed in the gearbox and back axle. Another application is to the penetrating oils now so largely used for lubricating leaf springs. After cleaning accumulations of mud from the spring leaves, it is only necessary to spray them with lubricants of this type, the penetrating qualities of which enable them to find their way between the metal surfaces. Similar oils are o vafluerthatntaov u er‘ oils are of value for lubricating coachwork parts, such as door hinges and locks, while, they can also be spread around body mounting bolts if these are producing squeaks.

STICKING VALVES When, because of an accumulation of gummy deposits on the stem, an engine valve sticks and refuses to close completely, the following expedient can be tried if the motorist, is far removed from garage help and it is not found possible to loosen the valve satisfactorily. A correspondent in an oversea technical journal states that he was in a quandary because an inlet valve had stuck open, and although it was prised several times so as to reseat it completely, the stem was so encrusted that the valve spring was not strong enough to close it. Had it been an exhaust valve it would have been possible to drive the vehicle slowly with one cylinder out of action, but the effect with an inlet valve was that the blow-back into the induction manifold prevented the engine from running. The remedy adopted was to slacken the tappet adjustment so that there was a very wide clearance, the effect being that the valve then only half opened, and did not reach the top of its normal lift, at which point it jammed. Such a procedure, of course, caused painfully noisy running, but enabled the car to he driven nearly 100 miles without damage or great loss of time.

HARDENED ALUMINIUM. IMPORTANT BRITISH PROCESS Interesting statements have been made in the British technical Press about a new method of treating aluminium, which, it is believed, will have far-reaching effects in the motor ’and other industries. The merits of aluminium and aluminium alloys when used for crankcases, pistons, cylinder heads, and other parts of the car are well recognised, but hitherto the employment of aluminium for certain work has been difficult, because the metal is comparatively soft, and corrodes readily when attacked by various acids and salts. The general principle of the new treatment is to transform by a special patented process the surface of the metal to a depth of ,0015-inch into aluminium oxide. The process employed, it is claimed, can be so regulated that this outer film is made so hard that it will cut glass, and cracks under bending stresses; or the surface of the metal can be so converted, that although it is far harder and more durable than plain aluminium, it. can be pressed, rolled, and punched without injury to the film. Another characteristic of the treated product is that, despite the hardness of the outer layer, it still remains fairly porous, and can absorb pigments and lubricants.

The original smoothness and lustre of the metal are retained, and it can be impregnated with any colour desired, and afterwards re-treated so that its crystalline formation is altered and the colour remains permanent. A valuable advantage of this porosity can be taken in such parts as pistons, which can be impregnated with colloidal graphite or mineral oil before assembly, and so will be in excellent condition during the running-in period of an engine.

Pistons made by the new process are also said to be superior to the. ordinary type, because their outer hardness delies penetration by foreign particles such as grit, and the wear’ of the piston ring slots is minimised. The heat couductivtiy of the piston is not altered. With the exception of the United States and Canada, the patent is controlled throughout the world by a British company, and in America several ol the largest factories have adopted it, and are daily “alumilii.ing” thousands of pistons. It is expected that this discovery will be widely used for many parts of the ear, including aluminium cylinder heads, water pipes, radiator shutters', and the hardware fittings of coachwork.