Light Agricultural Motors.
Page 2
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A Few Notes on the Comparative Performances of Light and Motors and Horse Haulage for Farm Work.
By an Agriculturist.
There can be no doubt that the agriculturist's requirements, so far as concerns the design and construction of a motor for farm work, should, in my opinion, weigh more with the designer than any other consideration. What is required by a farmer is a tractor which will replace horses, and it must be capable of drawing any one of the following implements : a reaper and binder; a grass mower ; a plough; a cultivator ; a roller. It should also be able to draw a wagon loaded with from two to three tons, and should further be capable of employment as a portable power plant for the driving, by belt, of any isolated machinery on the farm. k'or any of the above purposes, not more than a 20h.p. engine is required. In my opinion, it is a great mistake to attempt to draw two or three binders or reapers, at the same time, with one machine, as my experience shows that more time is lost in negotiating corners than is gained by being able to deal with an extra wide strip of land each time the machine travels up, or down, the field. The difficulty of driving round corners is greater when drawing a reaper than any other implement used on a farm, because the eorners, which have a very large radius at the commencement of operations in the field, gradually become more acute as the centre of the field is reached.
For the harder work on a farm, such as ploughing, there is no doubt that a heavy, high-powered tractor can do more work than a lighter machine, provided the land is suitable and has sufficient stability to carry the increased weight—.a condition which cannot obtain on land that is ploughed annually. When used on soft land, a heavy machine is very inefficient, because so much of its power is expended in the continual lifting of the tractor out of the ruts made by its own weight.
The accompanying table shows some interesting comparisons of tests which 1 have made with two tractors weighing, respectively, 16 and 26 cwt. All the experiments were carried out on the same land. Tests Nos. 1 and 2 show that the 10h.p. tractor was capable of hauling 5 cwt. per horse-power on dry land, and 3.5 cwt. per horse-power on wet land, against the 3.4 cwt. on dry land and 2.5 cwt. for wet land, obtained with the 16h.p. tractor, as shown in the tests Nos. 3 and 4. No. 5 relates to an experiment that I made, on dry land, with a. 10h.p. motor, the tare weight of which was 15 cwt., and I obtained the results noted. I then removed the 10h.p. engine from its frame, and fitted it in place of a 16h.p. engine on a tractor weighing 26 cwt., and a further trial showed me that, with the larger tractor, which -weighed 11 cwt. more than that used in test No. 5, the possible load was reduced by 15 cwt., as is shown in the figures for test No. C. These results were obtained with a tractor hauling a wagon on land, and they could not, of course, he obtainable on a metalled surface, for, on a well-made road, it must be admitted that the highpowered, heavy tractors work under more advantageous
circumstances. The light machine would not have sufficient adhesion to enable a load much greater than its own weight to be hauled.
As a result of experiments, I have found that a 10b.h.p. tractor, weighing 16 cwt., would do exactly the same work, on land, as a 16h.p., 26-cwt. tractor, and that at considerably lower cost for fuel and maintenance. From the farmer's point of view, a light-weight motor is more efficient, does less damage to the land, consumes less fuel, and is more easily handled than a heavy, high-powered machine. The former is also less costly to buy.
So much, then, for the 10h.p. motor, but a farmer occasionally requires a motor to drive a thresher, and, in order that it may do this, not less than 20h.h.p. is required, and for no other purpose, on a farm, need an engine of greater power be employed. Of course, there are some farms on which a 20h.p. motor could not do all the work, but, in those eases, I maintain that two such tractors would prove far more serviceable than one machine of double the power. The smaller unit is easier to handle, and, in practice, would be found more efficient and less costly to maintain. The amount of threshing to be done on some farms would hardly warrant the employment even of a 2011.p. machine, and on such farms strongly advocate the use of a light motor of 10-15h.p., and I have found that such a machine, for general farm work, may be worked much cheaper than horses.
Take grass cutting as an example: the cost of this kind of work varies, in different parts of the country, from 4s. 6d. to 7s. 6d. an acre, and 5s. an acre is a fair average price. I have kept careful records of the cost for this class of work done with a motor, and I find that I am enabled, with a tractor, to cut 3i acres per hour, as against 11 with horses, at a cost of 9YI. per acre, for fuel, oil, greases, driver, and the wages of a man to look after the reaper. To this cost must, of course, be added the interest on capital outlay, depreciation, and repairs. The machine to which 1 refer can be obtained for £200, and I estimate that it is good for six or seven years. That is allowing a depreciation of about 15 per cent_ per annum, and, from my experience, I should say that the cost for maintenance works out about the same percentage on capital outlay, or a matter of about £30 a year.
With the same machine, I find that I am able to obtain, in other branches of farm work, the following results : (1) hauling combined reaper and binder, I was able to cut and bind grain for 11d, per acre as against 48. per acre when horses are employed ; (2) hauling a two-furrow plough. I was able to turn over three-fifths of an acre per hour, at a total cost of 4s.; and (3) hauling a 7-tine cultivator, I was able to do 2iacres an hour at a cost of 13d. per acre. In the case of ploughing and cultivating, I am not able to give the cost for doing this class of work with horses, as I have not kept accurate records myself, and I have not had brought to my notice any figures which I feel I can accept as conclusive. In all my tests, the average speed of the tractor has varied from four to five miles an hour.
Finally, I should like to address a few words to motor manufacturers and tractor builders generally. In designing new tractors for agricultural use, manufacturers should bear in mind that the chief things to he considered, from the agriculturist's point of view, are :—extreme simplicity ; light weight: gearing enclosed in dust-nroof and, preferably, oil-retaining cases: the engine should be governed ; and, it should be of moderate power—not exCeprling 20h.p. When the right maehine is produced, it will find an almost unlimited market in this country, in our Colonies, and abroad.