Novel Principle in
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A New British Tractor
AGRICULTURAL equipment, of which the main feature is a tractor embodying a new principle and the design of which reflects 18 years' experience on the part of Messrs. Harry Ferguson, of Belfast, was demonstrated, on Wednesday, to a number of important men in the agricultural world. The event was held at the works of the maker, David Brown Tractors, Ltd., of Huddersfield, which is an associate company of David Brown and Sans (Huddersfield), Ltd., the well-known gear manufacturer.
Disadvantages Eliminated.
• The implements are attached directly to the tractor (each one can be detached in 10 seconds and coupled up in 20 seconds), which arrangement enables the machinery to be used in the most restricted spaces, because considerably less " headland" is required even than with horse-drawn implements. The disadvantages, however, which have previously been experienced with rigidly attached implements, have been eliminated by the ingenious new mechanism referred to above.
This consists of an hydraulic device which causes the implement to " float " behind the tractor, the depth being automatically maintained even when the driving wheels drop into hollows in the ground. The uniformity of cut, furthermore, is maintained, when operating transversely on sloping ground, by a compensating arrangement.
In the usual sense of the term, the tractor has no chassis, the rear axle and gearbox forming a transmission housing of unit construction, which possesses a high degree of strength on account of its cylindrical shape. Being made of an aluminium alloy, however, its weight is low. This housing also contains the hydraulic equipment, and is bolted to the engine crankcase, thereby ensuring the utmost rigidity in all circumstances.
The gearbox has three forward and one reverse speed, no constant-mesh gears being used. This arrangement provides that an hydraulic pump, coupled to the layshaft, operates only when the tractor is in motion.
In order to keep the weight down to a minimum, without detracting from the strength of the unit, the gears aie
made of nickel-chrome molybdertiiM steel, heat-treated to 100-115 tons per sq. in. The rear axle is sturdily. mad and comprises a pressed-steel bani(i casing, a spiral-bevel crown wheel and pinion, and a two-pinion bevel differential.
Developing 20 b.h.p. at 1,400 r.p.m., and having a bore and stroke of 3i ins, and 4 ins, respectively, the four-cylindered engine is designed to start on petrol and to run on vaporizing oil, costing 6d, per gallon. An efficient air cleaner is provided and .a magneto looks after the ignition.
Of the single-plate type, the clutch is operated by a pedal, which also controls the brake on the near-side driving wheel. A separate pedal is provided on the opposite side, acting on the off-side driving wheel. Steering is by worm and nut and is extremely light.
The Hydraulic Mechanism.
The marked success of the tractor is due to the hydraulic equipment, which consists of a four-cylinderecl camoperated reciprocating pump, which, as mentioned earlier, is directly coupled to the layshaft of the gearbox. It is shown at A in the accompanying drawing.
This pump feeds fluid to a doubleacting piston, .operating in cylinder B. The inlet of oil under pressure to the cylinder is controlled by valve C. operated by the conveniently placed handle D.
It will be seen from the illustration of the complete machine that there i4 a compensating link which couples an arm extending upwards from the implement with the control point E. on the tractor. Thus, when the driving wheels fall into a hollow or mount a ridge, the compensating link, via a system of rods, levers and cables, automatically adjusts valve C, which, in turn, brings the hydraulic cylinder into action, giving the necessary depth correction.
A particularly important feature is the functioning of these hydraulic and linkage arrangements when the implement strikes an obstruction.. With an appliance which is being hauled in the normal manner, the tendency, in such circumstances, is to raise the front wheels of the tractor, but with the device under consideration the rear wheels tend to rise. The traction is thus reduced, with the result that one of the driving wheels will spin harmlessly, and no damage will be done to the implement. • To surmount the obstruction, it is necessary merely to reverse the tractor a Jew feet to raise the implement, and then to go forward again and drop the implement. The only ground untouched will then be that immediately above the obstruction, The Ferguson tractor weighs 16-i cwt. and its equipment includes a 10-in. two-bottom plough, a general cultivator with seven tines, a three-row ridger, and a three-row cultivator with nine tines. It is available with pneumatic-tyred driving wheels for, road work, and is provided with an ordinary drawbar for straightforward towing. Provision is made for a power take-off.
Upon the success of this interesting machine depend, to some extent, the future prospect g of the British tractor industry. Many vigorous efforts have been made in the past to produce tractoss of wholly British design and construction, but hitherto keen competition has hindered their development.
In the case of this new Ferguson, the designer is well equipped with knowledge of the agriculturists' requirements and difficulties, whilst the maker's name carries a reputation in engineering circles that is above question. Provided that the functioning of the novel and ingenious hydraulic mechanism fulfils expectations, such a strong combination should not fail to make headway.