THE PEDRAIL.

Manawatu Herald, Volume XXXVI, Issue 1207, 12 February 1914, Page 4

THE PEDRAIL.

LATEST MOTOR TRACTION development. In the World's Work Mr James Armstrong gives particulars of the latest development of motor traction, Since the invention of the pedrail some ten years ago the design has been modified eight times, so that the latest model represents a very material advance on the original vehicle. Each pedrail places two and three feet on the ground alternately, and the force exerted by the compressed springs is adjusted so that any two feet together can carry the load for which they are designed, while one foot alone would be unable to do so. Consequently, when any abnormal load is thrown upon a single foot it merely rises, and the obstruction is passed over without any jolt whatever. When three feet come into play the load still

,is supported only, without any lifting effect whatever, because the springs are incapable of more than a certain definite extension. As a result, road obstacles are absorbed readily, and this constitutes the secret why pedrail motion is accompanied by such an easy gliding motion free from vibration. In the forward motion the main slipper travels on the anti-friction roller chain, while at the end where the loot-carrier turns, the latter is lifted bodily by means of a pair of specially designed sprocket-wheels. At the other extremity of the machine is a similar pair of sprocket-wheels driven by the motor, which impart through the foot-carriers the whole of the driving force to another specially designed chain. Thus the roller chains take no part whatever in the strains thus set up, their function being exclusively of an anti friction medium. The distribution of the weight in this vehicle constitutes a remarkable feature. Although the tractor weighs 10 tons the weight per square inch upon the ground amounts to only 1-llb, with a load and 71b in the empty condition. In the case of an ordinary wheeled vehicle of the same weight with eight inch tyres, with one-inch of the periphery of each wheel in contact with the ground, the weight per square inch is 7o(Jlb, From the operation point of view the economical advantage is completely in favour of the pedrail. The power required to work a pedrail train on the level or over moderate gradients is 60 per cent, less than is necessary to operate an ordinary wheeled train of the same tonnage. So far as earning capacity is concerned the advantage is more pronounced, being 150 per cent, greater by pedrail than by wheel haulage.