Agricultural Motors.
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A. comparison of the costs of ploughing by different systems should prove most interesting, taking, as a standard of comparison, a " Kid Kangaroo" doublefurrow plough, hauled by three horses in charge of a ploughman. The costs for various methAs of ploughing may be tabulated as follow :— (5) Double-engine steam ploughing with plough.
A brief survey of these figures, which, it must be borne in mind, are only approximate—because of the varying conditions under which ploughing takes place, and of my inability to produce data from my own personal observations of all the various methods IA ploughing, shows that the cheapest method, so far as actual cost of ploughing is concerned, is that with a compound steam tractor and a six-furrow plough. Se.e, note at foot of table for cost with steam tractor.-Ere]. A very-good second is the 30 hp. oil-tractor outfit, but, in this ease, there is a difficulty in estimating the cost of repairs; so much depends upon the owner's proximity to the works of an engineer who is capable of dealing with them. A 30 h.p. multi-cylinder oil engine is by no means the simplest of machines, and I am inclined to think the repair bill might be heavier than for a steamer, although, in the tables, I have allowed similar figures for each of these two cases. The figures which I have given above for cable ploughing by steam engines are those for which contracts may be made with engine owners; very-few farmers can afford a double-engine steam set of their own, but many hire them for much of the heavy work on their farms. The figures which I have given for horse ploughing may be accepted as accurate and as showing the conditions against which mechanical systems have to compete. There are other factors, however, besides the cost per acre, which will decide the farmer as to what method he should employ. The following is a summary of the five methods for which I have given approximate costs, and I also give the average farmer's arguments for or against the employment of the various systems. (1) This may be considered as the best standard of average horse ploughing; such a plough may be worked when the weather conditions would make the use of a motor impossible. (2) This system, owing to the lightness of the motor, its law first cost and simplicity, should appeal to the man who farms from 200 to 600 acres ; it is not the cheapest system, but it is cheaper than the standard. The tractor itself may he utilized for purposes to which horses cannot be applied, but farmers sometimes object to the nature of the fuel used.
(3) This system, the second so far as regards the cost per acre, entails a heavy initial outlay ; it is suitable for a farmer in a large way. The tractor alone could be used for many purposes other than ploughing. Some farmers still argue that the system is apt to be unreliable. (4) As T have already stated, I consider that this is the cheapest system, so far as the cost per acre is concerned, butt the weight of the tractor is on the heavy side, and, consequently, its effect on the land is not viewed with favour by farmers; further, it takes a longer time to get under way than the outfits of systems 1, 2 and 3, and it would not be used for harvesting, by many farmers, owing to their fear of its causing a fire.
(5) The most-rapid way of accomplishing the work, although not the most economical ; it cannot be varied economically to suit both shallow and deep ploughing— in fact, it is usually unable to do the former class of work. It can, however, reclaim land which could not he cultivated by any other system, although it is more susceptible to bad-weather conditions than the other methods named. Reviewing theee " average farmer's opinions," I am inclined to think that there is a future for small-sized motors. If marketed at acomparatively-low initial price, say, £120, a three-wheel-drive machine could be made useful on almost any size of farm, and large farms could employ several machines of this type. A fernier, as a rule, when increasing his plant, purchases more singlefurrow or double-furrow horse ploughs, rather than one large multi-furrow plough which would require the combined efforts of all his horses for its operation. A small motor, of the type mentioned, would have sufficient power for most of the usual operations on a farm, although it would not be " man enough " to drive a threshing machine; for the latter purpose, however, there should be no difficulty in coupling two motors to one machine. The engine should be constructed to eensume paraffin, if, in the particular locality where it is to be used, that fuel can Lie procured at less than hilf the cost of petrol; or, if a number were used on one farm, some of them might be run on petrol (for handiness and ease of starting, etc), whilst the ethers might be adjusted to permit of the. consumption of paraffin.
I will now outline, the different methods of power transmission which are adopted by well-known makers of agricultural motors; a comparison should be of interest. They are as follow :— (l) Two wheels with " lockable " differential gear. C2) Two wheels with free-wheel balance gear. (3) Two wheels with " lockable " differential gear and means for driving either wheel independently when required.
(4) Three-wheel drive.
(5) Four-wheel drive.
(6) A drive by means of a chain track, on the lines of the Hornsby caterpillar tractor.
The first of these is the one most generally used, and it may be looked upon as a standard for comparison. The second, method is cheaper to make than a differential gear, and, in that if one wheel slips, when on soft ground, the whole drive, at the normal speed of the wheel, is transmitted through the other wheel, it has a further advantage. Complications arise, however, when it is required to transmit the drive in the reverse, and, when turning round a corner, the drive is transmitted through the wheel on the inside curve only, a condition equivalent to gearing up the motor. The brakes, too, must be applied to each of the wheels themselves, because, on a down grade, they could easily over-run tIn3 axle. The third system introduces a little more complication, but it has the advantage, not possessed by other methods, of assisting the steering when rounding very-sharp curves. For all ordinary work, the differential acts as usual, but, on ground which is heavy or slippery, the differential gear may be locked and both the wheels driven as one, or, when travelling round a curve, one wheel alone—the one on the outside of the curve—may drive the tractor thus assisting the steering effect.
A three-wheel drive introduces still-more complications, which, however, bring advantages in their train. The two front wheels should have a differential gear, but the single back wheel may have a plain drive from the planetary member of the differential gear. The front wheels, of course, might be provided with a free-wheel balance gear, instead of the differential gear; in that case, however, only the single back wheel would be available for driving in a reverse direction and for the brakes. It is claimed that, on account of its three tracks, a threewheel-drive tractor has a better chance of getting a grip on the land or road, aml, in addition, the tractive effort is distributed more evenly over the land ; the adhesion may be so much as 50 per cent. better than that obtaining with system laie I..
The four-wheel drive introduces a second set of balance gear, either differential or free-wheel—a serious increase of complication ; moreover, unless the leaders be placed out of track with the rear wheels, the load distribution over the land is no better than that of a four-wheeled machine in which only two of the wheels are drivers.
The chain-track (caterpillar) system is very interesting. Messrs. Hornsby have conclusively demonstrated its ability to be used on ground that is absolutely unfit for any other system of traction. Boulders; bogs; railway lines: all have proved to offer no effective barrier to the progress of a " caterpillar," the working parts of which seem to thrive on mud as a lubricant, although, I believe, if the blocks which constitute the track are tn.° closely placed, sonic difficulty is experienced when the tractor is run over shingle or pebbles—stones are apt to jam the chain as it passes over the guide wheels. Banks of shingle, however, would not be encountered with agricultural work, and the application of this system on a. smaller scale than that built by Hornsby's would be very interesting, though I am afraid the expense of manufacture of such a drive would be prohibitive; yet, on very-soft land, it could be used when any other system would be impossible. Steering is effected by the application of
brakes to one or other of the tracks, which, of course, are driven through a differential gear ; very-accurate steering is necessary for ploughing, and I doubt whether the chaintrack system is capable of meeting this requirement.
Winding drums and wire ropes are almost entirely used for ploughing by heavy steam engines. It seems rather against all ideas of economy, to move the tractor across the land with the plough, as is the custom with directtraction ploughing, thereby consuming large quantities of fuel for its propulsion, and it is possible that a 20 h.p. tractor, if provided with a winding drum and a long cable, could do 50 per cent. more work per unit of fuel if it remained stationary and hauled the plough by means of the cable. Of course, two tractors would probably be necessary, and, consequently, the actual time taken to do the work might be about 50 per cent, greater than if both tractors were used on the direct-traction system. The time taken in setting out the field would not be worth considering, as the light tractors used would be very mobile compared with heavy steam engines, which are generally employed for cable ploughing. If a reversible balanced plough, of the Fowler type, were used, a considerable amount of time would be saved. Most tractors are fitted with winding drums, or they should be so equipped, and it should not be a difficult problem to increase the size of the drums, so that they would take about 500 yds. of cable. If exceptionally-great lengths of cable were required, a belt-driven windlass might be employed, but I do not think this would ever be necessary. Adhesion, when winding heavy loads, could easily be arranged, by suitable spuds, if the weight of the tractor were insufficient to allow dispensation with artificial aids to stability.