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GETTING THE BEST OUT of he FARM -TRACTOR ENGINE

23rd March 1940, Page 24
23rd March 1940
Page 24
Page 25
Page 24, 23rd March 1940 — GETTING THE BEST OUT of he FARM -TRACTOR ENGINE
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Which of the following most accurately describes the problem?

WITH more open weather conditions now prevailing, agricultural work is getting into its stride again and the task before the farmers of the country is really colossal. The unusually severe winter has held up practically all field operations, in a year when autumn work was backward and a big programme of additional work has to be faced.

Every available man and machine is needed to help in the foodproduction campaign. Every maintenance engineer, who can deal with tractors or implements, will be worked at full pressure, and many men will take on this job whose experience has been with other types of machinery.

An agricultural tractor, designed to start from cold onpetrol and operate on kerosene, or paraffin, as it is more usually called by the farmer, is less simple to maintain in good condition than an all-petrol machine There are pitfalls of which the inexperienced should beware.

The basic problem, of course, is that of securing proper vaporization of the heavier fuel. In this matter considerable variations in efficiency, from one make to another, are to be found. The vaporizing oil supplied to-day is often the subject of criticism, but it is confidently stated that the quality is as good now as it was before the war, and one generally A22 finds that failures are due to faults in operatic:1i'.

In the actual process of warming up, which is done on petrol, the quality of the vaporizing oil does not affect the problem. Yet, big variations are found in results, in the time taken before kerosene can be turned on in place of petrol, and in the quantity of petrol consumed for starting. A fundamental point is whether or not the machine be fitted with a thermostatic control for the watercirculating system.

Such a fitting is largely standardized among the leading American makes and it has the effect of preventing circulation of. the cooling water until the proper temperature has been reached, so as to permit the use of kerosene. Consequently, the warming-up period is reduced to less than five minutes under most conditions.

This effects a great economy in petrol consumption and allows the machine to be quickly and safely• -turned over to the cheaper fuel. It has been shown that by installing a thermostat in a machine which does not carry such equipment as standard it is possible to cut the warming-up period by as much as 20 minutes.

Whether or not the tractor has a thermostat, it is important in cold weather to make intelligent use of a radiator blind, preferably in conjunction with a temperature indicator. The radiator front should be fully covered when starting and uncovered when work is in progress to an extent which will enable the cooling water temperature to be kept just below 200 degrees F. Should this practice not be observed, and the tractor allowed to run too cool, poor vaporization will follow with evil results, which are referred to later.

A mistake that is frequently made is to keep a tractor idling while it is being warmed up. This not only wastes fuel which might be employed productively, but defeats the main object in view. Even petrol will, in such circumstances, not be completely burnt. A proportion, in an unburnt state, will get past the piston rings. It is far better to ,et the machine to work on petrol and to

change to kerosene when the proper temperature is reached. The operator then has some work to show for the fuel used and the tractor will be in better condition.

All operators who are conversant with the maintenance of petrol engines are aware of the troubles arising out of oil dilution in the crankcase, which may occur with the best of spirit. They should not be surprised, therefore, to find that, when dealing with engines run on vaporizing oil, they may encounter much more serious difficulty. Enough has already been said to focus attention upon the need for running the inachine at a high engine temperature.

In spite of all precautions, it is seldom possible to ensure perfect running conditions, and, therefore, it is usually found necessary to replace engine oil at fairly frequent intervals, if the motor is to be kept in reasonable order. Where operating conditions are good, the period in which it is safe to retain an engine oil of proper quality is, commonly, about 50 working hours, after which the sump should be carefully drained and refilled.

This practice, regularly pursued, will save many pounds in engine repairs due to bearing failures, which would probably occur should the diluted oil be retained any longer. It is also a more economical way in which to use oil, than to be constantly topping up a residue of contaminated oil which is more than half paraffin. Apart from playing havoc with the bearings, a badly diluted lubricant will, of course, lead to other troubles. Compression and, therefore, power are lost, because the combustion chamber is not properly sealed. This is a trouble which is progressive, because falling compression leads to still-worse vaporization. Rapid wear of cylinder walls takes place and a big bill for reconditioning is soon in sight.

Some people, upon investigating these ills, try to take a short cut to their prevention by suggesting that the machine be run on petrol. Assuming that the tractor is well designed to run on kerosene, there is no object in using a fuel that costs twice as much, apart from questions of rationing. The ills which have been described are avoidable. No more than a reasonable amount of common sense needs to be exercised, and the care taken is well repaid later.

If proper precautions be taken with a good tractor, there is no reason why results comparable with the running of a high-class petrol engine should not be obtained. In fact, the records of working hours without repair which have been put up by some of these machines are far ahead of the, results obtained with some road vehicles. Their life is very much in the hands of the

operator. D.McH.

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