A British All-wheel-drive Tractor.
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An Interesting Innovation which is being Tried Out by the War Department
T"EEd:PORTANT benefits obtained by conveying the drive through all four wheels whe-_.e exceptional country has to be traversed or where heavy articles, such as guns, have to be hauled, have long been recognized, and during the war many thousands of vehicles embodying this principle were employed on duties of an arduous nature.
When all _wheels are driven no difficulties are experienced through lack of adhesion or wheelslip caused by the throwing of the weight on to the non
driving axles, as sometimes happens where only two wheels take the drive.
Many vehicles of this type have been operating successfully in this country, and have proved Particularly popular with contractors and other users who, at times, may have to run the vehicles over uneven and sometimes yielding ground, but their benefits are even more fullyb emphasized when transport overseas has to be considered.
It is, therefore, natural that the War Department should place great importance upon the development of vehicles and tractors in which the drive is distributed over all wheels, and tractors to its order, desigmed on this principle, are actually in course of manufacture by John I. Thornycroft and Co., Ltd., as a result of War Department trials which have been made with an experimental type during the past year. It may be of interest to our readers to point out that a model of the Thornycroft machine is exhibited in the Government pavilion at Wembley, although the final design may differ somewhat from that shown
by the model, whilst following the same lines
Thedrawing which we include on this page has been made from the model as a guide to the general design. It will be seen that the gearbox is situated amidships, and power is conveyed to the front and rear propeller shafts through a central differential gear, the final drive to each axle being by overhead worm in a pot-type casino..
Steering is effected through the front wheels only, the differential shafts in this axle being provided with cardan joints, and the drop arm swinging across the chassis. There is a sprung platform • or turntable at the rear, and forwazd of this a power-driven winch.
Disc wheels with pneumatic tyres complete the equipment.