An Oil-engined Bristol Tractor
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Bristol Tractors, Ltd., Introduces a New Model with a Victor Engine and Another with a Jowett Petrol Engine
WE have from time to time referred to the design and progress of the Bristol track-laying tractor, which is unique in that it is of unusually small proportions for a track machine and has been designed upon lines which have definite agricultural objects. An important development is the inauguration of the new London depot, at Sunbeam Road, Chase Estate, Park Royal, N.W.10, which is DOW the headquarters of Bristol Tractors, Ltd.
The opening of the Smithfield Show, at the Royal Agricultural Hall, London, marked the introduction of two new additional models. The first of these has a Victor horizontally opposed 10 b.p. oil engine, which is totally enclosed and, of course, water-cooled. The engine is mounted upon a cast cross-member anchored to the frame channels, and is-dirqctly coupled to the bellhousing at the back. In other respects the tractor conforms to the standard specification. The price of the oil-engined model is £295.
The other new model is one with a B24 jowett horizontally opposed watercooled petrol engine, which is priced at £195, as compared with £175 for the standard design, which is supplied with a two-cylindered air-cooled engine.So far as we are aware, the oil-engined model is the smallest traetor that is available with this form of economical prime mover.
The introduction of these new engines does not affect the other parts of the tractor; the drawbar pull of over 2,000 lb. in low gear and of over 1,500 lb. in the middle direct gear remain as heretofore. The drive is taken to the front sprocket of each Headless rubber-jointed track unit, and the pressure per sq. in. upon the ground remains at the remarkably low figure of 41 lb., which occasions no compression of the sub-soil.
The overall width is 351 ins., whilst the centre-to-centre distance of the tracks is 281 ins. The machine is thus able to straddle two rows of potatoes without injury to the growing crops, and to work in hop-fields and vineyards. Instead of the conventional form of speed control, the maximum is set by the governor, and the minimum speed necessary to ensure steady motion when the implement is not working, i.e., at minimum load, is regulated by a separate control. On the master control lever, which effects the steering motion' is a decelerator button. Normally, the governor sets the speed, but operation of the decelerator button allows the minimum speed control to take charge.
In this way, when ploughing, the turn may be made steadily at a headland and the driver is able to regain full speed for working immediately the implement is in the desired line, instead of having to accelerate while the ploughshares are cutting the soil.
The Bristol tractors retain the forward mounting of the engine, which, coupled with drive to the forward sprockets of the tracks, makes it virtually impossible for the machine to be turned over backwards, despite the worst conditions of gradient and load.