THE TRACTOR TRIAL OF LAST AUTUMN.
If you've noticed an error in this article please click here to report it so we can fix it.
The Issue of the R.A.S.E. Official Report Brings Disappointment at the Paucity of the Information Conveyed.
THE LONG-AWAITED official report of trials of agricultural motors held at Aisthorpe, near Lincoln, last autumn, has at last been issued by the Royal Agricultural Society of England. It may be said of the report that it is better to be late than never to arrive at all, but its value is very small.
There is a certain amount of mechanical and scientific data presented in the report which should prove of some value to manufacturers, but in my humble judgment the report is of no use whatever to farmers. Perhaps that is as well, for at the price —7s. 6d.—it. is not likely to get into the hands of many practice agriculturists. The document is cold and soulless, affording very little interesting reading, a failing which might be excused were it possible to say that the imformation it contained was really useful. The report contains a full list of the officials, a page and a half of history of previous trials, a full reprint of the regulations and conditions of the Aisthorpe trials, list of awards, andj a description of each of the competing machines In regard to the description of machines, much of the matter printed is, in the case of many of the motors, now out of date.
The most interesting part of the document is in the report of the judges and the information contained in Table III on the speed of ploughing, fuel consumption, and cost per acre.
The judges point out rightly that the comparing of the performance of agricultural tractors is a much more complex matter than that of tractors intended primarily for use on the roads. The latter are designed usually for a single purpose, and although required to negotiate gradients as steep as 1 in 4 and to run in all weather conditions over both good and poor roads, they are not expected to perform the various duties required of the farm. tractor. This comparatively new 61a.ss of vehicle must be capable of running not only on a hard road, but on soft land; it must be able to do the work of the horse in ploughing, cultivating, harrowing, and harvesting, and to replace the hired portable engine in the operations of threshing and driving barn machinery and, occasionally, also, to serve Ls a tractor for hauling a loaded wagon or farm implement from place to place. Furthermore, it may have to be used in remote parts of the country, often far from well-equipped workshops, and it must be driven by ordinary . farm labour, a, large proportion of which is not yet educated in the treatment of a dabs of machinery essentially different from those agricultural implements with which the farm hand is already familiar. Like the road tractor, it must work in all weathers, but with the additional disadvantage that it must often be left out at night, merely sheeted down. When all them diverse conditions have to be met by a class of machine of quite recent development, it is. remarkable, and highly creditable to the manufacturers that., of so large .a number of entries as 46, as many as 08 should have been presented for the trials, and as few as two only should have retired during their progress. This uniformity of excellence very greatly increased the difficulties of judging, and it would have required extreme uniformity in the general conditions of the trials to permit of attempting to arrange the tractors in order of merit, whether for area ploughed per hour, for fuel consumption (or cost of fuel per acre), for drawbar pull, for adaptability to the driving of machinery, or even for mechanical design. In the larger classes several tractors were nearly of equal merit. But, taking into account all the conditions laid down by the Society, there was no difficulty (so the report, somewhat contradicting itself, says) in selecting the prize winners under these conditions, and the judges' decisions were unanimous.
So we are informed that the judges' decisions in selecting the prize winners were unanimous, but what I think most. of us had hoped was that the official report would reveal how the judges arrived at their decisions; as it is, there is no indication of this matter whatever, and one is left wondering as to how the prizes were awarded. The report goes on to point out one or two difficulties that were met with by the tractors. One in Class 2, working in the field near the aerodrome, had to be moved to another plot because a compass ring, a large circle cut in the ground and filled in with clinker and chalk, was found to come partially into his work. Another competitor was less fortunate, for, although no trace of its existence was visible on the surface, in the course of its work the plough encountered the remains of a hedge which had been cut below the level of the field, and filled and levelled carefully so as to ensure the smooth surface required for the landing ground of an aerodrome. This machine succeeded in making cuts through part of the buried hedge, but when all three plough shares became engaged with stumps of wood up to 11 in. in diameter, it was brought to a standstill. Such instances, of course, were duly allowed for, and had. no effect in diminishing the credit due to the competitor. Differences in the depth of the soil were found in all the fields, even in the one that was being ploughed on the first day, and which was considered to be an ideal field. When clue allowance was made for this, the renort states that the tractive effort required to haul the ploughs varied little over the whole area. All competitors were easily able to perform their work on this field—viz., the field ploughed on the first day (September 28th) by tractors in Class 2_ It will be remembered that Class 2 was the largest class, and was for tractors not exceeding 30 h.p. hauling a three-furrow plough. When engaged on heavy and medium land on the third day, the same tractors did excellently on the medium, but not so well on the heavy land. Those who witnessed this test know that it was as stiff as any class land in the country, and it is interesting to note the report stating that the land was described as six-horse, but apart from that the land had never been ploughed as deep before. Deeper ploughing for the tractors was necessary for their proper loading ; the dynamometer revealed that the mean drawbar pull for the ploughs varied from 770 lb. to 1,130 lb. per share in different parts of the field. Nor was this all, says the report, for an irregular zone of stiffer land ran obliquely across part of the field, affecting only some of the competitors, which were exercising as great a drawbar pull for two ploughs as other machines were for three furrows in another part of the field.
Conditions were approximately equalized by changing the position of the tractors from one part of the field to another. When rain had fallen, the mean drawbar pull was reduced by about 15 per cent., because the cutting quality of -this particular clay was improved; but the conditions of adhesion became more difficult.
Comparisons of Drawbar Pulls and Acreage Ploughed.
The judges' report then sets out their method for comparing the figures of fuel consumption and allowing for the inevitable differences, in drawbar pull. It was by assuming a standard drawbar pull per plough share of 500 lb., and then reducing the observed pull and acres ploughed by this figure. The term " equivalent acres" is used, meaning the number of acres that would have been ploughed if the drawbar pull had remained constant at 500 lb. per plough share, estimated from the actual arawbar pull observed and the actual area ploughed. This scientific information should prove of value.
It is further pointed out that, in addition to the practical information obtained by comparison of the actual drawbar pulls and the actual acres ploughed, the judges had before them figures of comparison ,calculated to show what the results would have been if the resistance at every plough share had remained constant at 500 lb.
Thus, in the case of light land taking a minimum drawbar pull of 670 lb. for two ploughs (335 lb. per plough), the equivalent acre was only two-thirds of the actual acre, whereas in the • case of the heavy land having a maximum drawbar pull of 6,260 lb. for five shares (1,250 lb. per plough), 2i equivalent acres would have been ploughed for each actual acre. A standard depth was also taken for the furrow. The records of the actual depths ploughed were then examined, and if the mean actual depth over the whole plot exceeded the depth ploughed while the dynamometer record was being obtained, this fact was taken into consideration.
Class 1 (not exceeding 24 h.p. and hauling a twofurrow plough) on light land, showed that all the competitors were easily capable of performing their task ; but, as in other cases, there was found to be considerable difference in the drawbar pull, vafying fr'orn a minimum of 335 lb. per share to a maximum of 565 lb. per share.
The entrantS in Class 3 (tractors over 30 h.p. hauling four furrows) and Class 6 (internal-combustion double-engine sets) are reported to have performed the work allotted to them in their respective fields with great ease.
In the ease of the steam tractor and the steam double-engine sets, it was found unnecessary to obtain any comparative figures as there was only one entry in each class, but the work is reported on as being very satisfactory.
In regard to Class 7 (self-contained Motors and ploughs) the ploughs differed, and trouble as experienced in one case in clearing the plough. Owing to the impossibility of inserting the dynamometer between the tractor and the plough, no records could be made of the pull required.
Figures for the cost of labour in ploughing were reduced in terms of pence per acre, on a uniform basis of eighteen pence per hour for each attendant.
The fuel used has been taken per actual acre ploughed, and, where comparisons have been made on the basis of equivalent acres, the figures so obtained are also given for minimum and maximum consumption, and for the average of the five best tractors .i.n each class. Figures are also given (in
Table 3), but there is no purpose served in going into
the matter of costs. The judges' reports set the price of petrol and coal, but gives no indication of the actual cast of the different tractors for fuel. Five best tractors in this connection are referred to, but it is not stated which they are.
One or two interesting points arise under the subheading of " General Observations" in the judges' report. Of the 36 tractors, four were supported on chain tracks, and, in these, no case occurred of jamming by •stones or other matter. Special mention is made of a feature in the Ricardo engine which was fitted to the Peterborough tractor. On this tractor there was a simple device for turning a small portion of the exhaust gas direct into the carburettor, thereby warming the intake air and (according to certain authorities) diminishing the the tendency to "pinking." This enables the engine to run at full load without the necessity of injecting water into the cylinder. Trunk pistons were alsa fitted to this engine, and in the opinion of the mechanical judges, the engine stood quite in a class by itself, both as regards novelty and robustness of design. Special mention is made of the carburetter used on the Moline plough.
The Success of Paraffin Fuel.
The perfecting of paraffin carburetters was cracked up by the judges, who expressed themselves as agreeably impressed day the absence of smoke clouds either when running under load or when running light. A dirty exhaust was quite exceptional. The efficiency of water-washing arrangements for cleaning the intake air was not tested. The judges rather back up the experience of practical men in regard fa the need for a hand-throttle for reducing speed in the ease of governed engines. Boiling of the water in the radiator is said to have occurred only in one or two cases. There was a tendency to clogging in the case of a few tractors having the wheels near the frames and working on foul land with much grass. The tables given in the report are of very little use with the exception of Table III. What the farmer wants in tables of this kind is to be aSsisted in judging which tractor would be the most suitable to his soil conditions and what it would be likely to cost. No information whatever is given as to the costs of running any particular tractor on light or heavy land. All that is given is a, certain amount of information which might be useful to manufacturers, but it is of no use whatever as a guide to farmers. The same remarks apply to the matter of the drawbar pull. The resistance of the land at various points in the field was taken, but nothing is said of the drawbar pull of the tractors. • In Appendix III is given some rather useful information on the cost of ploughing land in the district
in which the trials were held. Anaissor.