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Maintenance Poii that Make for Petrol Saving

4th November 1939
Page 38
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Page 38, 4th November 1939 — Maintenance Poii that Make for Petrol Saving
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Which of the following most accurately describes the problem?

The Problem of the Haulier on Short Leads and Frequent Stops. Carburetter Tuning as an Aid to Economy. Care of Tyres. Mechanical Features that Call for Attention

Solving the Problems of the Carrier

" FOOLS rush in where angels fear to tread," I have been told, in reference to my article in the issue dated October 21, wherein I purported to show that an economy of as much as 20 per cent, might result from more careful driving, especially the avoidance of high speeds, rapid acceleration and heavy braking. I have been told that, whereas it is safe to predict some economy, it is too daring to quote figures. Well, my view is that if you are going to offer some advantage, it is necessary to be categoric and to indicate the value of the offer in some positive way.

Nothing of the advice which was given in the previous article is likely to be of much use to the haulier whose principal work is running over short distances, who is engaged on work involving frequent stops and starts. His drivers have not much chance to run at high speeds, especially if most of the work be in congested areas, and there is not much that can be done in the way of reducing acceleration or braking.

• Look to the Carburetter •

For their salvation it is necessary to look to the carburetter. Incidentally, hauliers whose vehicles run longer leads can exercise indirect supervision over their drivers in respect of speeds and acceleration by attention to the carburetter in the way I am about to describe.

It should be realized that the standard setting of the carburetter as it is turned out from the vehicle-manufacturer's works, is designed to give power rather than economy. It is true that, of late, vehicle makers have been giving more attention to the matter of petrol consumption. Some, indeed, have always done so, but even in those cases they dare not go quite so far, under normal conditions, as might be justifiable now.

The thing to do, therefore, is to communicate with the maker of the carburetter, or with the maker of the vehicle if there be any doubt as to the make of carburetter fitted, and ask for instructions on how to detune. Do not attempt to do this work yourself, without expert guidance, and, above all, do not imagine that you will attain your objective by fitting a smaller main jet, or by the more inadvisable practice of trying to hammer up the jet.

What is required, and this applies particularly to those hauliers whose vehicles are on short hauls or on retail deliveries, is to reduce the quantity of mixture passing, not merely the quantity of petrol. To do the latter is to upset the mixture ratio of petrol and air to an unknown extent, with even more unpredictable results.

Considerable savings in petrol can be effected, in the attic of vehicles on short hauls or on work which involves A28 frequent stops and starts, if the engine he switched off for every stop of over a few seconds in duration. An hour's idling throughout the day will, in the case of most heavyvehicle engines, use a gallon of petrol.

One point which must not be overlooked, if this procedure be adopted, is the need for the battery and electrical equipment, the starter and motor in particular, being in sound order. It would be a good idea, in the case of the many vehicles which are not subject to routine preventive maintenance, to start the era of economy by thoroughly overhauling the electrical equipment.

In cases where a certain amount of idle running is unavoidable, as when much of the work is in congested traffic, when it is not always convenient to stop the engine every time the vehicle comes to rest, make provision to ensure that the waste of fuel is reduced to a minimum by overhauling the carburetter setting, stopping all air leaks between carburetter and engine—this may mean the fitting of new valves and guides in old engines—and checking over the ignition equipment.

• Simple Electrical Check-ups •

Check over the contact-breaker points ; see that they are clean, with flat fades, and that the break is correct as to width. Clean and adjust the sparking plugs in the same way, and make a habit of paying more frequent attention to these matters.

One more point before I leave the engine. If the vehicle be an old one, it will probably pay handsomely to have the carburetter overhauled by the makers, especially if it be one of the type which has a number of moving parts. I have known cases where a couple of pounds spent on that has been repaid within a month or two. In one case— and here I can mention percentages without fear of contradiction—the consumption was improved in this way to the extent of 56 per cent.!!

Tyres come next for consideration and inflation pressure is important. A good deal of petrol is wasted by running on soft tyres, as the results of the following test will show:— A popular-type vehicle was used, with 7-in. tyres. For the first test they were inflated to 40 lb. per sq. in. A route 5`k miles long, practically level, and over a good by-pass road, was traversed in both directions and a reading taken for each. The average consumption was at the rate of 12.6 m.p.g., which is reasonable, • Low Pressure Means Lost M.P.G. •

The tyres were then deflated to 24 lb., as measured by Schrader gauge, and the same process repeated. This time the consumption return was 11.5 m.p.g., showing a loss of 1.1 m.p.g., which is nearly 10 per cent. On a weekly consumption of 90 gallons, that would mean a difference of four gallons per week, due to inattention to tyre pressure.

It would seem to be advisable, therefore, during this time of petrol shortage, to adopt the practice of many big bus operators and not a few large hauliers and ancillary users of testing tyre pressures every night. Do not overinflate, at least not to the extent of more than a pounl or two, because it creates a tendency to bounce, with resulting wheel slip, which tends to waste petrol rather than to conserve it.

The next thing is, in part, a matter of chassis maintenance, but it has also to do with tyre wear. I refer to the need for checking wheel alignment. It is surprising what a large percentage of front wheels are not properly aligned, with the proper amount of toe-in, as _.-ecommended by the manufacturers. Misalignment affects the wear on the tyres, of course, but it is often overlooked that it can have a considerable effect on petrol consumption.

It is estimated that misalignment of as little as in. has an effect equivalent to that of pulling the vehicle along the ground sideways for one mile in every 180 that it actually travels. That adds about 40 per cent, to the resistance to motion of the vehicle and must have a corresponding effect on petrol consumption. Certain it is that attention to wheel alignment is one of the essentials to increased m.p.g.

• Axle Alignment is Also Important • Incidentally, when attending to wheel alignment, it is advisable occasionally to check axle alignment, too ; that is to say, to see that the two axles are parallel, as a fault there can be just as effective in increasing tyre wear and fuel consumption as misalignment of the front wheels.

Next for attention come the brakes, which must be examined to ascertain that they arenot binding, also to see that the operating mechanism works freely and is well lubricated, especially where that mechanism includes cables.

The point here is that, whilst on a rough check the brake shoes may be free, there is the chance that, if the operating gear he tight the shoes may not come away from the drums so quickly as otherwise they would and should. The percentage of fuel savings as between a vehicle with free brakes and one on which the brakes are binding is something which I am not going to try to estimate.

The transmission should be given the " once over," to see that everything is running free. One tip is worthy of note here, in reference to lubrication of gearbox and rear axle. Clear out the old oil and replenish with fresh oil, with a preference for a lubricant not quite so thick as usual.

Now, I have offered some fairly big reductions; 20 per cent, as the result of limiting speed, or of care in stopping the engine when the vehicle is stationary; 10 per cent, by keeping tyres well inflated; anything up to 40 per cent, by ensuring accurate alignment, and some further reductions by care of brakes and transmission.

• Routine Maintenance Well Repaid • It will, of course, be appreciated that the percentage savings suggested are those which would apply in very bad cases. A vehicle which could be improved to anything like the maximum degree, as indicated above, must indeed be in poor condition—one of those, perhaps, taken from the scrap heap, to replace one which has been impressed.

One point, at least, is clear. Operators whose provision for maintenance is good, following a regular routine, and, to a reasonable degree, preventive, will reap the benefit now in a bigger mileage from their petrol ration than their fellows, just as, in the past, they have benefited by being able to run their vehicles farther per gallon of fuel.

Those who have not been so meticulous in this matter of maintenance will now discover how much it pays, aid the outcome no doubt will be that the industry in general, after the war, will rise to a higher standard in that respect than hitherto. Again showing, as I stated in the previous article, that good may come of ill.


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