Oil Engine for David Brown Tractor : New Track-layer
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WHEN thc David Brown Cropmaster VV tractor was first placed on the market, plans for a suitable oil engine were already in being, so that the machine in question was actually designed to take not only the petrol or paraffin power unit, but also the compression-ignition engine.
This unit has now made its appearance. It was introduced to the trade at a convention staged in Harrogate last Friday, although for the past year preproduction models have been on bench test and on practical work under varying conditions throughout the country.
The new unit is notable, as an oil engine, in that its weight is only about 100 lb. greater than that of the standard Cropmaster engine at present in use, and it has 'shown itself fully capable of standing up to heavy tractor use under a variety of conditions.
Tractor Costs £625 The complete oil-engined tractor, with electric starter, power lift, six-speed gearbox, front and rear pneumatic tyres, Iwo-speed belt pulley, power take-off unit, adjustable drawbar and dual bench seat is priced at £625 retail, which is only £150 more than the paraffin model. Against this increase, it is reported that consumption is only a half-gallon of oil fuel per hour, which represents a considerable economy, and that the machine can generally be relied upon to work in a higher gear ratio than its paraffin counterpart.
The oil engine is, of course, a product of David Brown Tractors, Ltd., Meltham, and in general dimensions is similar to the petrol-paraffin engine, there being many interchangeable parts. For the present year, limited production is scheduled, but later, owners of existing Cropmaster units will be able, if they so desire, to convert their machines to oil fuel by installing the new engine.
The oil engine is a 21-litre fourcylindered design of 31--in bore and 4-in. stroke. At a governed speed of 1,400 r.p.m.. 25 b.h.p. is developed. The
direct-injection principle is used, with a combustion chamber of toroidal form in the piston top. The injector nozzles are of the four-hole type. spraying directly into the combustion chamber, symmetrically with the vertical axis.
Situated outside the valve cover, the injectors are inclined to make for easy access during maintenance. A C.A.V. unit-type fuel-injection pump, with individual high pressure metering plunger and sleeve assembly for each cylinder, is employed. The whole fuel system is easily accessible, being inounted on the near side of the engine.
On the occasion of the convention already mentioned, an announcement was also made of the new David Brown Trackmaster, a track-laying 1 radto r adapted from the Cropmaster. For the present this model will not be available with oil engine.
Entirely different from any previous model produced by the company, the Trackmaster has a power unit giving approximately 30 b.h.p., and whilst the fuel consumption is higher than for the paraffin-engined Cropmaster, the figures per b.h.p.-hour are lower. To meet the requirements of various markets, two models with different track widths are to be produced, each model being capable of adjustment to a second track measurement.
. Among the new products introduced at the convention was an end-tipping trailer, designed by the David Brown technical staff and built by Messrs. Alley Trailers. Rated as a 3tanner, it has a graintight body of all-steel construction, 10 ft. 6 ins, long and 6 ft. wide. The wheels are mounted towards the rear, so that the load is partially shared by the rear wheels of the tractor, The body can be tipped to an angle of 40 degrees by the operation of the tractor power lift. The trailer costs about £133.
Another innovation introduced was a power-controlled earth scoop, which is likely to have a particular appeal to farmers in overseas countries.