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Agricultural Motors.*

5th January 1911, Page 14
5th January 1911
Page 14
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Page 14, 5th January 1911 — Agricultural Motors.*
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Which of the following most accurately describes the problem?

The purpose of my paper is to treat the subject of agricultural motors in a strictly-general manner, and, whilst a description of the good points of the more-successful and better-known agricultural motors will be included, I wish more particularly to emphasize their weaknesses and the difficulties with which designers of this class of machine have to contend. That there is a large scope for the application of the internal-combustion motor on farms cannot be gainsaid ; the mere fact that, amongst the industries of the world, home, foreign and Colonial farming is one of the largest, if not th e. largest, is sufficient proof of the enormous scope for motor-operated implements. Moreover, the very nature of the work, which, to a large extent, is of a repetitionary character, and of the simplest kind, deliberately clamours for the application of selfpropelled and automatic machinery.

Farmers, it must be admitted, are of a very-conservative nature, and, therefore, the problem for automobile .engineers is, not only to produce machinery which will meet farmers' requirements, but to convince them of the practical nature of mechanically-propelled implements. Steens, to a large extent, has postponed the advent of the internal-combustion motor, and undoubtedly it is, and will remain, a powerful competitor with internal-combustion engines. Steam, however, has many shortcomings, and the motor of the future must be designed to eliminate these objections, as well as to introduce new and powerful economic advantages. For small, portable and stationary power plants, oil and petrol engines, to a large extent, have already replaced steam, and but-few farms of 500 acres and upwards are without an engine of this kind. The power of these small engines varies from -3 h.p. to 7 h.p., at about 400 r.p.m.; above 7 h.p., steam still predominates.

The purposes to which small engines are applied consist of chaff cutting, root pulping and slicing, oil-cake breaking, and various other barn operations, and, for these purposes, the machines are generally arranged so that they may be driven by belting off a main shaft which is driven by the engine. Petrol or oil engines are also frequently employed for water pumping, but in such cases the motor is also used for other purposes on the farm. A email portable oil or petrol engine may prove very valuable for elevating when harvesting hay or corn, the only alternative sources of power being obtained from a portable steam engine, which is too powerful and requires too much attention, or from horse-operated driving gearing, which needs a boy in constant attendance; the latter -method is expensive and is very slow in its operation. For all these purposes, simplicity, reliability and economy are essential features, and the present considerable demand for small motors would undoubtedly he largely increased if they were produced with greater care and more .attention to detail.

Petrol should prove a more-suitable fuel than oil: the

annual fuel bill for a small engine is not very great. The undoubted advantages attending the use of petrol—ease and promptitude of starting, and proportionate economy when working on a light, or rapidly-fluctuating load, which last-named condition does not conduce to the good of an oil engine—are sufficient to justify the use of the lighter fuel. -The ignition gear should be either high-tension or low-tension magneto, and, if a second system be fitted, it should be a duplicate of the type adopted in the original design. The use of accumulators, or batteries, should be 'avoided; in the past, they have done much to prejudice farmers against petrol engines. If circumstances make an oil engine preferable, it should be capable of being run entirely on oil, and not dependent on petrol for starting purposes. Cooling would be more satisfactory if effected by air, rather than by water, provided the risk of overheating were eliminated, and also provided the fuel efficiency and simplicity of construction were not sacrificed. The advantages of the two-cycle engine are well worth considering. Lubrication must he mechanically maintained, and the oil should he carefully filtered, as also should the supply of fuel, because, during operations in the barn; the atmosphere is usually heavily laden with dust of a very-fine and penetrating character.

As regards external finish, polishing is quite superfluous, but, whenever possible, the parts should be painted ; little time is spent in cleaning the parts, and, if they are of polished steel, they will soon rust. Both workmanship and design must be beyond question, and all parts should he capable of ready interchange with new ones. These demands, however, in many cases, are met by many engines already on the market, but the problem which still remains to be decided is that of the application of internalcombustion engines to field operations. such as ploughing, cultivating, drilling, harvesting and threshing. Ploughing and cultivating by mechanical means have received a considerable amount of attention from steamengine builders, and John Fowler and Co., Ltd., has set a high standard by the economical and rapid way in which its steam ploughs perform this class of work. The mostpopular form of steam ploughing is by means of two traction-type engines, each of which indicates 60 h.p. to 100 h.p., fitted with winding drurns carrying from 450 to 700 yds. of steel cable; these engines are placed at opposite sides of the field, and they alternately haul the plough to and fro across the field. Turning of the plough is not nevessary ; it is constructed as a double-ended implement— one set of ploughs or tines acting in each direction, and the set which is out of action for the time being is lifted clear of the land. Headlands of approximately double the width of the engine are left at each side of the field, and these areas are afterwards tilled in a direction at rightangles to the previously-made furrows. The objections to this method of cultivation are heavy initial cost of the engines, implements and tackle, and the lack of economy when working in small fields. The " roundabout " system of ploughing, which system reduces the first cost of the plant by calling for a single engine with a 'sortable anchored pulley block on the opposite side of the field, reduces the first cost of the outfit, hut much time is lost in the laying-out of the tackle, and less work can he done at one setting than with a double-engine set.

The direct-traction method of ploughing, in which an internal-combustion engine draws a gang plough, is already a serious rival to steam. This system is gaining ground, and it is undoubtedly far more suitable for small fieh's than the cable method ; moreover, the initial outlay is such that the average farmer can well afford to possess one set of sufficient capacity to deal with the acreage of his tilled land, and at the same time the tractor may be made of great value to him for other purposes, such as threshing, and for hauling his produce to the market or to the nearest railway station, The principal objection to tractor tilling is the waste of fuel caused by driving the motor as well as hauling the implement, over the land, and the compression of the subsoil with the consequent reduction of its drainage capacity due to the passage over it. of the weight of the engine.

Several makers of steam tractors and internal-combustion motors have done a good deal of experimental work, in connection with the direct-haulage of ploughs. The best known amongst makers of the latter chess of outfit are lye], Marshall and Saunderson. Messrs. Saunderson construct a large range of tractors, the smallest being of 6 h.p. to 7 hp .: this is provided with four wheels, two of iihich are 2 ft. 8 in. in diameter with 7 in. treads ; these two wheels are the drivers, and are provided with a freewheel device instead of a differential gear ; there are three forward speeds (2i, 3, and 6 m.p.h.) and one reverse speed ; the engine has a single air-cooled cylinder., and a belt pulley is fitted so that the tractor may be used as a stationary engine; it is capable of hauling a single-furrow plough, which implement is attached direct to the frame; 2!, acres a day is said to be its eapaeity. A single-furrow plough, drawn by two horses, on average land, will turn over about one acre a day ; the increased rate of -work Clone by the motor is effected principally by increasing the speed, but there is a certain ploughing speed beyond which any increase means a lower quality of work done; ILL fact, it is generally agreed that it is better to plough slowly and to cut a number of furrows at a time. This small machine, a-hen used as a tractor, is capable of hauliug, on reasonable roads, a 30-cwt, load, and, cousequently, it may be used for hauling reapers or binders on the field. The second Same:le-rem model is similar to the first, with the exception that it is more powerful, and has a 12-14 lel). water-cooled engine and driving wheels 3 ft. in diameter. Two other models, of 30-35 lep. and 45-50 hp respectively, are also made: by this company, all of which models have four road wheels. The most interesting of the Seeinderson tractors is. perhaps, the three-wheeler. all the wheels of which are driven ; the two lending wheels ars also steerers, whilst the differential gear is FO arranged that the drive is equally transmitted to both the front a-heels and the back wheel, and, therefore, better adhesion is secured, The three-wheel drive of the Sautelerson has many advocates, and it is designed to enable the tractor to work on land over which it might. -be impossible to operate with a machine having the usual type of VA o-wheel drive.

The free-wheel substitution for the differential on the light Sannderson tract-or is undoubtedly good in many respects ; besides being about the simplest method of enabling the machine to be driven round a Mr11P1', it also has the advantage that, if one wheel grips whilst the other cannot do so, en aecount of its being on a soft patch, the gripping wheel will not stand still whilst the slipping wheel revolves at double its normal speed, as is the case when an ordinary differential is fitted. Reversing can he arranged by clutching one wheel only. The Tye]. agricultural motor, the maker of which claims to be the pioneer of direct-traction ploughing, has two driving wheels on a differential axle-, whilst steering is

effected with a single wheel of small diameter : it is driven by an 18-20 tan-cylinder water-cooled engine. The complete machine weighs about 35 ewu. Only one speed

in beth directions is fitted, and it. certainly scents that -two more, which might be fitted at a compaintively-small extra cost-, would prove advantageous. The Marshall oil tractor is well deeigned, anti is constructed of excellent material; it is fitted with a twocylinder, 30-11.p., water-cooled oil engine, and the steer mg is effected with a swivelling front axle on tractionengine lines; its total weight is about 5 tons. The Marshall tractor was submitted to an interesting test some two years ago, which tests were officially observed by a representative of THE COM M ER CIAL MOTOR, the object being to ascertain how much land could be ploughed during a continuotie run of 24 hours, and to prove that the engine could be worked for long periods without giving any trouble. A certain amount of time was lost daring the night, but, even with this loss of valuable: minutes, 2li . acres were completed in the 24 hours. After charging • every possible cost against the tractor, including interest on capital outlay, and depreciation (at 20 per cent. per annum), the cost per acre came out at 3s. id. The Marshall tractor is, of course, also adaptable to ether operations on a farm ; it is capable of hauling loads up to 6 tonsat 4 m.p.h. along ordinary roads, whilst it will drive a. threshing machine with a 4 ft. 6 in. drum--the size usually. used with a 7 n.h.p. steam engine.

I have still one more tractor to. describe; it is at present under construction and has riot been tried, so I cannot speak of its capabilities. Its design contains several novel features, and these are calculated to overcome many of the faults of the usual type of tractor. Perhaps it will be better that I should here describe some of the failings of the usual type. Undoubtedly the greatest difficulty experienced with both steam and petrol (or nil) tractors is-that of obtaining sufficient adhesion to operate over heavy land without being rei heavy that much damage is done to- the hind and to country lanes. It cannot be said, at present, that any tractor, unless it be the Saunderson

three-wheeler, can be employed wherever horses can obtain a grip, but, if motors are to be made popular among

farmers, this condition must be secured. The fitting of spuds on the wheels se-ems to be the only arrangement at present which tractor makers think necessary; tc secure. adhesion on the land, but it must be admitted that this method is bath crude and inefficient ; in fact, it. is little better than running on octagonal wheels, because, after • a spudded wheel has run a very-short time over the land, . clay and soil adhere to the sides of the .spuds and effectively fill up the spaces between them, the wheel then becoming anything hut a round one ; yet no tractor, unless it be the Saunderson, would ever be used without spuds . when ploughing on " greasy " land.

Another difficulty is that of steering while exerting aheavy drawbar pull. Easy steering is essential, as it is

often desirable that a tractor be driven round a small. radius, especially when it is drawing binders or other

harvesting machines; when ploughing, also, on the eide of a heavy gradient, with the drawbar pull rather to one side,

there is a considerable tendency for the tractor to skid down and away from its correct course. Another point is the tendency of makers unduly to complicate their machines; efficiency is highly desirable, but, when simplicity of construction is sacrificed for the sake of economy of working, farmers are apt to think a machine is quite beyond their comprehension and management. The weight of the tractor should be reduced as much as possible, if pleughing and cultivating by direct traction is to be Made successful. The Ivel motor, with its 18-20 lep. engine and a tare weight of 3.5 cwt., is an example of what can be done, and as this motor can draw ploughs which would usually be drawn by at least four horses, each of which may weigh from 12 to 18 cwt., no farmer can raise the question of undue compression of the subsoil against

that machine. In the case of a heavy tractor, scaling from 5 to 7 tons, there is legitinntte cause for protest from the farmer, and every effort should be made to reduce the weight.

Improvement in the matter of fuel consumption is also tlesirable, and a reduction in the gross weight of the tractor will go far to lessen its demand for fuel. As agricultural motors are now designed and made, when employed for stationary work, threshing, etc., they are easily beaten by any good compound or expansion steam engine. A 7 /1.11.p. steam engine, if properly handled, will drive a threshing machine all day (about 9 hours), on approximately cwt, of coal, costing about Is. a cwt., wylst a 20 teli.p. internal-combustion engine would consume. according to the statements of several makers, something in the neighbourhood of 18 gallons of petrol (or oil) in the same time, at a total cost of from Os. to 20s.—a very-serious item in the working cost of the machine. The same proportionately-low running cost results when a steam tractor is used for ploughing.. At the same time, I feel sure that great. economies in the rate of fuel consumption will be made, when makers ot agricultural motors decide to fit more-efficient engines and carburetters. There are plenty of good 20 lip. motorcar engines in use to-day which are almost incapable of consuming two gallons of fuel per hour. Briefly. then, the follnwing improvements in the design and construction of tractors for agricultural purimes should urgently be effected :— (1) lucrea,sed driving-wheel efficiency, when working on heavy land :

(2) improved steering arrangements, when working on soft ground, so as -to enable the machine to be steered round a small radius while exerting a heavy din what' pull ;

(3) greater simplicity than that at present prevailing; (1) lower rate of fuel consumption per b.h.p. hour. The Ideal " tractor, which, as 1 have already re

marked, has not yet completely materialized, bids fair to meet the first and SOCOntl of these requirements. All its wheels are large in diameter, but the driving wheels are comparatively narrow, so that they may roll freely in a 10 in. furrow. Instead of the usual spuds, or paddles, the driving wheels are provided with a number of radial arms; these are guided by slots in the rims of the wheels and by similar slots through an inner ring which is secured to the hub. The inner ends of these radial arms are provided with rollers, and, as the wheel rotates, the arms are pushed outwards from the wheel centre by reason of their rollers' travelling over a circular cam, which cam is secured to, but is adjustable for the amount of its eccentricity on, the axle; the maximum stroke of each arm occurs when it is in contact with the ground, but, as it leaves the ground, each of the arms is withdrawn within the rim of the wheel, thus clearing away any earth which may have adhered to the projecting end. The cam may be adjusted so that it is concentric with the nxle, and, when in that position, it imparts no motion to the radial nrms ; these parts, therefore, do not then project beyond the rim, and the wheel may travel over hard roads without doing damage to the surface. The cam may he set in any position between full-stroke and no-stroke of the arms, according to the state of the surface over which the tractor may be driven. 1'rovidet1 that this arrnugement of radial arms works satisfactorily in practice, the " Ideal " tractor wheel should prove to be a considerable improvement on the present standard type.

Another feature of the " Ideal " tractor is the arrangement whereby the differential gearing can be locked or freed, so that the wheels may be driven through the differential gearing, in the ordinary way, or both driven at the same speed ; ferther, the arrangement provides for time transmission of the whole of the power through either of the rear wheels, the opposite wheel merely riding idly on the axle. This system of driving should prove of great assistance, when tern* the tractor within a very-small radius, or when travelling over soft land with a heavy drawbar load, which load may be all to one side of the tractor—a condition of haulage which, as I have already stated, makes steering somewhat difficult on soft or greasy land.

The two more-important purposes for MLitt the " Ideal " tractor was designed are ploughilig and mowing implements for both these operations limy he attached to the innehine. SU as to convert it into a self-contained unit. ("or ploughing purposes, a frame, to %%hid, any type

or number of plough bodies may be at is arranged at the rear end of the tractor this frame may be raised or lowered, by means of a set of levers and perallel-motion bars. The arrangement permits of the plough's keeping an even " keel " when ploughing, even if one of the tractor wheels be in a furrow while the other is on high ground. The cutter-bar for mowing is carried on the off side of the teactoi, and is oscillated by means of a small chain-driven crankshaft—in much the same manner as that adopted on horse-drawn implements of the same type. Both these fitments—for ploughing and mowing—may be removed, when the tractor is required for haulage or stationary work. The engine which is being fitted to the first machine is of the four-cylinder type, and develops about 24 h.p. The total weight of the tractor is estimated at from 4:5 to 50 cwt.

(To be continued.)

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