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The Results of Recent

29th December 1931
Page 48
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Page 48, 29th December 1931 — The Results of Recent
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Which of the following most accurately describes the problem?

AGRIMOTOR

By INVESTIGATIONS

World wide Efforts are Being Made Further to Improve the Agricultural Tractor, and this Article Enumerates the Results

ALTHOUGH the agrimotor is in some quarters thought to be as far advanced as it is possible to make it, experiments and investigations are proceeding all over the world to develop it still further. Changes in practice also give rise to the need for constant research, in order to adapt the necessary power to the requirement of these changes.

Much attention has recently been devoted to the economy of wheel diameter and the question of wheel grip, investigation of these problems having received serious consideration during past months in Continental countries, especially in Germany, Russia and Scandinavia.

Experiments have been conducted at Bornim (Germany), where there is a trial track for tractors, on the subject of increased diameter of tractor driving wheels. This, within limits, gives better output. The German technical journal, Techinik in der Landwirtschaft, reporting in this matter, states that for driving wheels a diameter of 1,05 no, is uneconomic. For normal types of soil a diameter of 125 in. or 1.30 m. seems to be suitable.

As regards speed (an important point), the practice of keeping tractor speeds within the neighbourhood of those of horses, which has hitherto been done, is not favoured. These speeds are about 2 m.p.h. to 2i m.p.h. The effect of steam ploughing, which is usually done at over -4 m.p.h., is considerably better.

Another difficulty that the Germans are trying to overcome is that of adhesion. Track-laying machines afford quite sufficient tractive grip, but they are regarded as too expensive and costly in wear. A track-laying tractor described in the German journal has a weight of 2,640 lb., whilst the wheeled tractor weighed only some 950 lb. With an engine power of 12 h.p., it developed about 6 h.p. at the drawbar.

The question of materials for track-laying machines is being studied in a special laboratory. A )334 type of wheel, which has been evolved by a special committee of inquiry said to give 19 per cent. more efficiency than a normal wheel, is described in the German journal.

Spuds for the agrimotor have received consideration in Scandinavia. In some tests carried out in Denmark the Government report on the subject expresses a preference for wedge-shaped spuds, especially when these are provided with selfcleaners. Trials of agrimotors in 1930 at Ultuna, Sweden, have confirmed the superiority of this type of spud over angle irons.

On wet ground an agrimotor with angle irons dug itself in when the drawbar load exceeded 1,760 lb. A similar tractor with V-shaped spuds with scrapers reached 2,420 lb. with only 9 per cent. slip.

The latest Russian tests concern the application of a power take-off witk the combined harvesterthreSher. The principles upon which the machine under test has been designed is that the power required for actual threshing of the ear is considerably less than that involved by the passage of the straw through the drum.

Consequently, the threshing drum is arranged so as to thresh the ear and leave the straw so far as possible untouched. According to Technik in der Landwirtschaft the saving of power aimed at was not attained.

By the way, two articles in Agricultural Engineering (U.S.A.) for June, 1931, are worth noting. One by W. L. Zink traces the origin of the idea of the power take-off to a French inventor, M. Albert Gougis, who, in 1906, used it with a

corn binder in the harvest field. In 1916 it was taken up in America, but did not become generally known until 1925.

The advantages of the system are that it gives an efficiency of 80 per cent, or more, as compared with 50 per cent. by using the drive of the land wheels, and the power can be applied while the tractor is stationary.

The other article by P. N. G. Kranick, on the development of the grain combine, approves the idea of smaller combine harvester-threshers operated by the power take-off. Even on larger farms, the writer says, it may be found to be economical to use two or more smaller combines with smaller tractors in place of one large machine.

I have recently been reading Bulletin No. 362, entitled "Dust and the Tractor Engine." The Amen(ens are much more accustomed to operating their tractors in dust than we are and they take more trouble to exclude it from the engine.

The bulletin gives particulars of tests on a series of different air cleaners. It states that where no air cleaner is fitted a tractor running under dusty conditions will be ruined by 15 hours' work. The dustseparating efficiency of the different cleaners tested varied from 42,7 per cent. to 99.8 per cent.

In Great Britain no tests of any importance have this year been conducted in public, and no reports of the results of other tests have As yet been issued. The type of machine attracting present attention is the row-crop agrimotor.

The features of this type are that the tools are attached directly to the frame in front of the driving wheels, it has a high ground clearance and quick-turning powers. It is thus able to work among growing crops-. At present, a Massey-Harris model of this type is undergoing tests at Harper Adams Agricultural College, Shropshire, and an International Farman at Cambridge University.

Concluding, attention may be called to reports issued this year by the University of Agriculture, of tests carried out with three agrimotors at the Institute of Agricultural Engineering, University of Oxford. The agrimotors tested were Vickers, Fordson and Austin makes. The reports are issued separately and are numbered 27, 28 and 29 respectively, the first being priced at 31d. each and the others at 2Scl. each by post. They can be obtained from H.M. Stationery Office, Kingsway, London, W.C.2, or through booksellers.


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