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AGRIMOTORS FROM AMERICA.

4th October 1917, Page 20
4th October 1917
Page 20
Page 21
Page 20, 4th October 1917 — AGRIMOTORS FROM AMERICA.
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Details of the Clydesdale and Avance Agricultural Motors.

Agrimotor design has fallen into two well-defined channels. The one school accepts the three-wheel principle, the other adheres to four-wheel practice. A few days ago we were invited to witness a new representative of the last-named category.

This is the Parrett—marketed in this country by M. Martens and Co., Ltd., 15a, Wilton Street, Grosvenor Place, S.W. 1, as the Clydesdale, which constitutes the generic name of all motor vehicles issuing from this house. The deinonstration in question took place at Spring Park Farm, Shirley, near Croydon.

The Clydeadade, well conceived and substantially built, should prove eminently suitable for the British farmer. The frame, of well-braced 7-in, steel channels, gives ample strength and rigidity. The ell-known vertical watercooled four-cylinder en bloc Buda engine of the ordinary motorcar type, with a bore and stroke of 44 ins. and 4 ins. respectively, developing 12 h.p. at the drawbar, and 25 h.p. at 900 revs, per min. on the belt, is set transversely in the frame, the radiator and fan being set, endwise. The motor is governed, the ball-type throttling governor being directlyBohneeted to the ,csitburetter, thus ensuring economial fuel consumption pat all speeds. All parts of the engin are readily accessible, the bonnet being ionovable, and allowing valves to be ground in with engine in situ, while the crankcase may be dropped and the bearings examined or taken up without disturbing the engine, the frame being eo cut as o facilitate this operation. two speeds forward-2a and 4 miles pm hour respectively—and one reverse— LB miles per hour—are fitted. The drive on lobth high and low gears is direct. The high and low gear pinions slide on a pulley: wheel sleeve, and these mesh with a single doable-faced gear. The last named runs inn dust-proof housing and dips in oil at every revolution, so that ample lubrication is assured. The final drive to the tractor wheels is through familiar differential to heavy bull-rings mounted on the driving wheels.

C58 Special attention has been devoted to lubrication throughout, while the selfaligning ball bearings on end of crankshaft, to take up strain of belt work, and on either end of the differential shaft respectively, also run in oil. The bull pinions and rear wheels are interchangeable, this feature contributing to even wearing of the parts. Control is simple, there being only a

gear and clutch lever. When it is desired to stop the tractor it is only necessary to throw out the clutch, and this action automatically applies the brake, thus bringing then machine to a. standstill. By narrowing the frame and bonnet forward the driver is afforded a clear unobscured view of his work, being able to see both front wheels.

The tractor is adapted to run on both petrol and paraffin fuels. The capacity of the two compartment tank is 18 gallons. The Parrett paraffin vaporizing system follows the usual broad lines, the heavier fuel, after being atomized, being gasified by being brought into contact with the exhaust at its hottest point, subsequently being combined with the air which has been passed through a cleaner. One carburetter is common to both fuels with easy change-over system. In starting up from cold petrol is used, and the motor is run thereon for about ten minutes, when the heavier fuel is brought into use. In accordance with popular practice a fine spray of water is injected into the gas and air mixing chamber when paraffin is being used. The wheels follow the usual American lines, the spokes, of g-in. round steel, being screwed into hub and riveted into rim. The front wheels have a diameter of 46 ins. by 4-in face with central flange, while the driving wheels are • 60 ins, diameter by 10-in, face and fitted with spnds to ensure adequate adhesion. By narrowing the frame forward it is possible to obtain a short turning radius —9 ft. 8 ins. inside—while by giving the front wheel ample diameter enhanced leverage is secured, enabling the tractor to operate on soft, uneven ground with a lesser absorption of power for pushing the tractor itself than would be the case were small wheels employed. The wheelbase is 7 ft. 8 ins. ; length overall, 12 ft. ; width, 6 ft. ; height, 5 ft. 6 ins. The foot-plate is roomy, with steel plate platform.

By virtueof the three-point suspension the machine is given extreme flexibility, which, combined with the low centre of gravity, enables the tractor to adapt itself readily and safely to ground inequalities. The central pivot suspension of the front axle permits the latter to swing freely up and down. The low centre of gravity minimizes capsizing upon rough or soft land. The degree to which canting may be carried is convincingly depicted in our illustration of the machine ploughing through a depression in the field. As a matter of fact, it is possible to tackle a difference of 30 ins. in the level of the ground between the two driving wheels with perfect safety. The Clydesdale is of the straight-pull type: the attached implements are hitched to a centrally-disposed drawbar. This involves two wheels running in furrow, which z in combination with the positive steering system, secures selfsteering. It may also be mentioned that R is essentially a one-man outfit. The land upon which we saw the Clydesdale at work sufficed to test its abilities to the full. It was hauling a three-furrow self-lilt Case plough, driving a furrow 6 ins. deep. The field was dirty, having been under clover for some two years. The heavy loam was inclined to be gravelly. When work was first started the soil was somewhat puggy, but upon drying out under the sun. turned more easily and cleanly. Rough turning was followed, it being intended to leave the field under fallow for the winter and to cross-plough in the spring. From the ease with which the three-furrow plough was drawn we should think the tractor amply powerful to haul a four-furrow implement over this land, and ploughing to 8 ins. even 'under the worst conditions. The length of the furrow was 190 yards, the total turn being 30 ins., wed the cut was covered in n minutes on low speed.

The Avance Agrimotor.

Another ag,rimotor of American origin complying with the expression "Universality" is the Avance. It can be used for ploughing and cultivation, haulage, and for driving stationary engines, so that it May he aptly described as an all-round machine, such as seems to have a distinct vogue upon farms in the States.

The engine is a single-cylinder model of the two-cycle type, developing 12 h.p. at 500 r.p.m. In general design and principle it is very similar to stationary and marine hot-bulb engines, such as are built in this country by Petters, RustonProcter, Campbells, the Torbinia etc., so is. of the two-cycle, part-scavenging type with pump mjection of fuel. Crude-oil, residual oil or kerosene may be used as fuel, provided the oil contains no water or impurities.

The Avance, from the plough being integral, is essentially a motor ploug and not a tractor. On the other hand the ploughs are so constructed that they can be raised, and the rear end of the unit is so built that the other implements can be attached, and the farm or road worked with there. The flame is composed of two longitudinal I-beanie held together by cross members. This main frame is not only narrowed in at the front but also has what might he called a " kick-up " at the rear, that is, the pivots for the ploughs, driver's seat and other rear parts are on a higher level than. the engine and other parts at the front. Between the two angle-shaped cross members at the front, which, are set back to back, is the fronteaxle,'disposed _on a large horizontal bolt so that the entire front axle may be tilted at a considerable angle. This front axle is an I-beam section of considerable height, and generally resembles very closely the average I-beam lorry front axle. The wheels differ, however, in that while the same diameter, the right is set lower than the left to allow it to run in the furrow and still keep the engine and other mechanism practically level.

The rear or driving wheels are transversely flanged for additional traction, but the front wheels have only a central flange to assist in keeping a straight track. Both are of the steel spoke type. The rear wheels are mounted on bearings on a solid axle, and have attached to them the large spur gears by means of which they are driven. The right wheel is made larger in diameter (to correspond with the lowered right front wheel) than the left since it most run in the furrow.

The different diameters of the rear wheels cells for different speeds, and

these too must vary when the machine turns to the right or left. Also, the power of the motor must be transmitted in such a manner that each wheel can he given any speed independent at the other. For this purpose the power from the motor is transmitted through spur gears to a central difkrential, thus distributing the speed automatically between the two wheels. The differential is of the bevel type and is equipped with a lock so that both wheels may be forced to drive. This lock is operated by means of a separate hand lever. Other units in the control are the right pedal for the clutch, the left pedal for the brake, and the lever operatine the

gears, which allows of changing the speed. Within the flywheel proper is placed the cone clutch of the usual type, and to this is attached the first of the spur gears. The driven member of this pair is so mounted that its shaft may slide within it, and in the centre is mounted the driver of the second pair. Farther along on the same shaft is mounted another smaller gear, while the driven member is made with two gears suitably spaced, eo that the movement of the hand lever will throw aut the first and throw into mesh the second. In this way a high and a low speed are produced as well as the central or neutral position. This gearing gives three reductions, from the engine to layshaft, from layshaft to differential shaft, from differential shaft to rear wheels.

In addition to ploughing, the right front wheel is readily removed, and when power is desired for churn, pump, separator or other farm machine, the motor plough is run up to the point where the power is needed, the front axle jacked up, right wheel removed, and a special supporting bracket put on in its place. Then by means of a belt on the pulley and with the gears set in the neutral position, the engine is entirely disconnected from the machine and is ready to supply power. For this purpose the speed should be lowered to 410 r.p.m. The motor is reversible, as, when it is necessary to reverse the plough, the motor is caused to rotate in the opposite direction. This is accomplished by moving a single interlocked control lever, by means of which the engine is slowed down, and the position of the cam actuating the fuel pump is changed so that the timing is altered. Consequently a pse-ignition occurs, and this early firing causes the crenkshaft to turn in the opposite direction. In running order the agrimotor weighs three tons.

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