Much Ado About Smoke
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BRITISH road transport oil engines, their injection pumps, and the maintenance of both, also of the injectors, must be in the first rank, for we have little trouble with smoky exhausts. It is only in very hilly areas, where the power units are working to almost their full capacity—and then, not in many cases—that anything like a heavy discharge can be seen.
In the early days, when many units were in their experimental stages, governing was, perhaps, not quite so effective, and the methods of combating smoke 'emission were possibly not fully understood, there was a certain amount of trouble. Now the modern unit in this country is so cleverly designed and the combustion chambers and injectors so well arranged that only in cases where engines are very old or maintenance neglected, does an oil engine advertise itself as such.
A smoky exhaust may result from over-richness of the mixture, which causes a free emission of unburnt particles of carbon. This may be caused by bad governing or considerable wear between cylinders and pistons; the wear permitting excessive supplies of lubricating oil to reach the combustion chambers, where they• are utilized as fuel. The exhaust is, however, comparatively harmless, there being a far smaller proportion of carbon monoxide than in the case of a petrol engine in similar circumstances. Our engines are usually governed at the injection pump, so that the supply of fuel is cut down before it can become excessive.
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Exhaust Smoke Indicates Inefficiency Heavy smoke from oil engines is an indication of inefficiency. It means that full use is not being made of the fuel and that much is not being properly burnt—in other words, full advantage is not being taken of the inherenteconomy of the compression-ignition principle. What is the use of going to the extra trouble and expense of producing oil engines if we then proceed to dissipate at least a part of what has been gained?
During a visit to Germany some time ago, we were astonished at the amount of smoke belching from the exhausts of many vehicles and tractors. Probably their maintenance ,had been neglected during the war, and it may be that since then improvements in this particuJar respect have been effected. belching Oil-engined Trucks From America, however, in Causing Fog comes news that throws some light upon conditions there as regards the employment of oil engines. It seems that Los Angeles is suffering from a persistent smoke fog which is becoming quite a problem for the municipal authorities. This must be particularly disturbing in view of the reputation for sunshine for which that delectable part of the States has always been renowned. At roughly 3,000 ft. above the city, is what is termed an inversion layer of air, above which height it is warmer. Consequently, a slight mist which is heavier than the warm air above clings around this "ceiling," the added smoke giving a browntinged atmosphere which, at the higher levels of the city, limits visibility and irritates the lungs.
Los Angeles County is situated between mountains, the exits from which are high, and so the fog cannot escape. Whilst much of the fog may be caused by smoke and fumes from factories and certain industrial establishments, the authorities are investigating. other sources, and one of these is smoke-belching trucks.
A Motor Patrol to Arrest " Smog " According to the "Commercial Car Journal," a "Diesel Patrol has been formed, comprised of two cars operated by the Los Angeles County Air Pollution Control District, and penalties up to 500 dollars can be inflicted where the stiff antismog laws of the County have been violated, " smog " being the abbreviation for the two words, " smoke " and "fog." An offence may result only in a warning, this depending, however, upon the heaviness of the smoke.
To ascertain its density, use is made of a circular screen, divided into five sections, each indicating a certain percentage. The operator looks at the smoke through a hole in the centre, and can estimate its density fairly accurately by comparing it with the section to which it approaches most closely in colour. Incidentally, this comparator is copyright. Each of the patrol cars averages 2,000 miles a month and scours the main highways. The average number of summonses is 76 per month. A25 The immediate effect is that the trucking companies are co-operating well and doing their best to cure the offending units, by conducting early overhauls or making necessary adjustments.
A few days after a vehicle has been caught, the owner receives a questionnaire, and from this the officers concerned determine if he has endeavoured to abate the nuisance. In the event of his efforts being satisfactory, the form is suitably marked and filed, and no further steps taken unless the offence be repeated.
In dealing with drivers, a distinction is made between where the patrol men believe the excessive smoke to be caused by the engine itself or whether it be due to mishandling. Keeping the accelerator flat down on. the floorboards is often -found to be a cause, whereas', the driver who handles a vehicle careful]; call do much to obviate the trouble.
The panel which makes decisions concerninu, such vehicles is known as the Diesel Smoke Abatement Board, and represents an example of co-operation between the trucking companies, the unions and Government officials, the .members being drawn from all sections., The need: for suchprecautions is indicativ'e of the extent to which the oil engine is being used in America, but it seems that the makers. and users of the equipment have still something to learn from the old country.