In the " World's Work " Mr James Armstrong gives particulars of the latest development of motor traction. Since the invention of the pedrail some ton years ago the , design has been modified eight times, so that thq latest model represents a very material advance on the original vehicle. Each pedrail places two and three foot 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 arc 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 foot-carrier turns, the latter is lifted bodily by means of a pair of specially-designed sprocketwheels. At the other extremity of the machine is a similar pair of sprocketwheels driven by the motor, which impart through .the foot-carriers the \vhol'-> of tho 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. Tho 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 141b, with a load and 71b in the empty condition. lii the case of an ordinary wheeled vehicle of the same weight with eight-inch tyres, with one inch of tho periphery--of each wheel in contact with the ground, the weight ncr square inch is 7001b. From the " operation point of view the economical advantage is completely in favour of the pedrail. Tho power required to work a pedrail train on the lovol or over moderate gradients is 60 per cent, less ' than is necessary to operoto an ordinary wheeled train of the same tonnage So far as earning capacity is concerned the advantage is more pronounced" being 150 -ncr cont greater by pedraii than by wheel haulage.
Permanent link to this item
WALKING MOTOR-CAR, Ashburton Guardian, Volume XXXIII, Issue 8797, 18 February 1914
WALKING MOTOR-CAR Ashburton Guardian, Volume XXXIII, Issue 8797, 18 February 1914
Using This Item
See our copyright guide for information on how you may use this title.