Keep Up Engine Heat for Economy
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A Contributor with Wide Experience Gives Practical Advice on Cutting Down Running Costs CONSTANTLY contacting with all '4.-"classes of commercial-vehicle operator; from those having single vehicles to others with fleets of hundreds, I am forced to conclude that a large number of the persons engaged in maintenance lack either a knowledge of first prin.. ciples, or an appreciation of the changes that recent years have brought in this industry.
A few words on these are merited in order that what follows may be better appreciated, so we will consider first the change in Conditions, and secondly, the alterations in design and construction which have come about as a result.
• For purposes of comparison, I will take the period of the past 20 years, which more or less covers the lightweight vehicle from its inception to the present day, for it is with this type that I am mainly concerned. Traffic conditions have changed vastly during this time, particularly in so far as short hauls in towns are affected, and it is in this type of work that we are most interested.
Waste Under Modern Conditions Quite apart from the actual increase in the number of vehicles, which, of course, results in congeStion, we have one-way streets, involving waste mileage to the detriment of the ton-mile figures, and • many more controlled crossings. The collective effect of all these facts must be . waste of time, coupled with an increase in wear and tear, particularly on clutches, brakes, tyres, transmission, etc., and heavier petrol consumption. • Of even greater importance is the effect upon the engine, for although the crankshaft rotates many more times for the same mileage than before, the unit runs under worse ctinditions of temperature than its predecessor, but I shall' deal with this later, as I am certainly convinced that this specific matter is not .properly understood by the Majority.
Vehicles on long-distance work have also suffered a change due to a variety of circumstances, most important of which is legislation. One effect of this has been to compel an operator to keep his vehicles on the road every available minute if he is to make any profit worth having,
High Load-to-weight Ratio
In addition, the lightweight vehicle has been called upon to carry heavier loads over longer distances than ever before, which fact, taken with the firstmentioned condition, renders careful and regular maintenance more than ever necessary. All too often the reverse is its lot—to the ultimate detriment of the machine and its operator's bank balance.
This is where the old proverb, " a stitch in time saves nine," translated into the two words, " preventive maintenance," takes on a very real meaning, and it is safe to say that the operator who has fully appreciated its message, and properly applied it, suffers. less from lengthy visits to the repair shop and temporary loss of a vehicle as a result.
In this connection I cannot too strongly emphasize the importance of keeping an accurate record of mileage, petrol and oil consumption and all repairs, together with particulars of the maintenance given to each vehicle and the intervening mileages, because only in this way is it possible to check careless driving, or some of the methods adopted by unscrupulous drivers to acquire a little extra time or money at their employers' expense. Clever, indeed, is the commercial-vehicle operator who knows what happens to his vehicles once they are out of his sight.
The organization running a big fleet —large enough, that is, to warrant the employment of a separate maintenance staff—is even worse off on this question of personnel, and it is obvious that with the increasing difficulty of obtaining skilled men, standards of workmanship will fall, and this must he reflected in the feliability of the vehicles.
This trouble with labour is my main reason for stressing the advantage of careful records and charts, which, if closely watched, have the effect of minimizing to some extent the errors of the human element. In addition, the operator is less dependent on the individual for information by direct questioning, which is liable to be unsatisfactory.
Seek Expert Advice
One last point from the general aspect of maintenance is that, when an operator encounters some difficulty or peculiarity in connection with the vehicle, advice should be sought from the maker of the vehicle or the supplier, who, in the case of the larger dealers and distributors, frequently has on the staff at least one technician qualified and willing to assist.
I mention this because I encounter so many people who try to struggle along on their own without seeking specialized knowledge from those who could and would be able to solve their problems. I say this without in any way deprecating the knowledge of such operators, but merely to emphasize that engineers whose job it is -to make contact with their concerns' clients from a technical angle are brought in touch with an infinite variety of operational conditions which puts them in a favourable position as advisers.
In considering the various aspects of engine maintenance, it is as well to remember the difference between long and short-haul work, and the effect upon this vital unit.
Long-distance work, when a good speed is maintained without frequsatt interruption, is so suitable for the modern high-efficiency engine that apart from regular changes of oil, cleaning of external oil filters, maintenance of correct adjustment of ignition points and clearance of fuel lines, results will usually be satisfactory without further thought. In the case of short hauls, however, very different conditions apply, and, if the best results are to be obtained much more attention is demanded.
Temperature is a primary factor, the importance of which is only just being realized; in fact, from my observations it would appear that many operators have considered it solely as a result of its having been forced upon them by the cold spell last winter.
Relation of Mass to Heat The mass of metal in the engine of a current 3-tonner is much less than that of a comparable model of 20 years ago. The same applies in the case of the radiator. This is all to the good when considered in terms of weight alone, but, unfortunately for temperature control, the less the mass the more rapid is the dissipation of heat. This is undesirable for the following reasons.
The main cause of cylinder-bore wear is corrosion—a phenomenon brought about by condensation, usually as a result of the engine running too cool. Again, poor petrol consumption is frequently due to a lack of temperature causing loss of power from failure to use all the gas at every stroke. This is manifested by deposits of soft carbon, which, in turn, promote sticking valves.
In addition, the life of the unit is affected by the resulting sludging of the sump oil, which leads to choked filters and feed galleries, starvation of lubricant to big-end bearings and scoring of crankshaft journals. This formidable array of troubles is due, in the main, to a lack of temperature control, which.deserves to be regarded as a vital factor. I repeat that only rarely is the question properly understood and suitable action taken to mitigate its effects.
Perfect Temperature Control Now the ideal temperature at which to run an engine is 180-190 degrees F., and it must be made clear at the outset that there is no way in which perfect control of temperature can be obtained, with the possible exception of thermostatically controlled radiator shutters.
Fortunately, however, there exists a cheap and easy way of effecting a reasonably accurate control, but in order to. ensure the maximum benefit from it, it is necessary to take some trouble in the application of the scheme. This will be amply repaid by the results achieved.
Bearing in mind that the temperature desired is 180-190 degrees F., or 82-88 degrees C., it is advisable to start by ascertaining the highest temperature reached by the vehicle on its regular
work. This can easily be done by inserting a thermometer in the water.
Next, cover the radiator for, say, half its area with a temporary blank, such as a sheet of brown paper, and check again, tearing off strips of paper at each test until the desired figure is recorded; in cold weather more may have to he added until probably twothirds of the radiator is covered.
Having ascertained the area to be blanked off, it remains only to obtain some sheet zinc or aluminium, to cut it to size and to secure it to the front of the radiator grille in place of the brown paper. It is, of course, impracticable to give accurate proportions, but for the popular makes of light 2and 3-tonners I suggest for very short runs two-thirds covered in winter and one-third in spring and autumn, or even in summer, except for heatwave conditions, , whilst for longdistance work roughly half-blanking will probably suffice in winter.
For the best results, obviously, a temperature test under actual working conditions is necessary. Assuming a mileage of 5,000 during the time the radiator blank is in use, and admitting to only 1 m.p.g. improvement, a sum of .E3 7s. 30. will be saved (using petrol at Is. 5,1d. per gallon) on each vehicle.
Because a greater saving than this can often be obtained, I submit that the trouble on this score alone will have been worth while, but, in addition to this direct saving, longer engine life and fewer overhauls will follow automatically by reduction in carbon deposit, less sludging of lubricating oil by carbon, diminished condensation and almost complete elimination of sump dilution by petrol.
Finally, I will quote the figures I have actually obtained on test with two British vehicles, one a 25-cwt. van and the other a 5-ton lorry. The route chosen was a circuit through fairly busy suburban streets and the day of the test was' fairly cold with considerable wind.
On the 25-cwt. vehicle with the radiator unblanked, the temperature was 62 degrees C. (144 F.) and the petrol consumption 20.8 m.p.g. Blanking the radiator for three-quarters of its area brought the temperature up to 80 degrees C. (176 F.) and the petrol consumption return to 23.2 m.p.g.
In the case of the 5-ton lorry, the figures were much the same. The temperature, before blanking, was 59 degrees C. (138 F.), which returned 12.8 m.p.g., whilst it rose to 76 degrees C. (169 F.) with the •radiator blanked to the same extent as on the van, and consumption improved to 14.4 m.p.g.
These figures speak for themselves and show the value of taking some trouble in the interests of accuracy, and are surely sufficient recompense for the trifling expense incurred.—R.D.