Engineering Wonders of the World
Volume III

302 ENGINEERING WONDERS OF THE WORLD. line between France and Italy. The line was to follow, more or less closely, the route of the existing road, which has a The Mont historic interest as having been Cenis Road. AT completed by the great Napo- leon, for military purposes, in the years 1800 to 1810, during his occupation of Piedmont. To reach the summit elevation of 7,000 feet, steep inclines, with a maximum gradient of 1 in 10, would be needed ; and as ordinary locomotives, depending for their adhesion on tho weight carried by the driving wheels, would not be able to climb inclines of such steepness, Mr. Fell proposed to over- come the difficulty by using a system of his own invention. As the system is in use on the Snaefell Railway,* Isle of Man, and on a railway in New Zealand, it may be as well to describe it somewhat fully, using the present tense. DIAGRAM SHOWING THE FELL CENTRE-RAIL TRACK AND GRIPPING WHEELS. The Fell System. The permanent way consists of ordinary cross-sleepers, carrying two track rails, be- tween and equidistant from which is a double- headed centre rail, laid on its side and mounted eight inches higher than the ordinary rails, on steel chairs bolted securely to the sleepers. The locomotives are provided with four cylinders, one pair to work the vertical or carrying wheels, the other to drive two or more pairs of horizontal wheels, which, by means of a screw-gear, can be made to grip the centre rail on both sides with the force required by the gradient travelled over. Car- riages are provided with horizontal flanged * In this case the system is not used for hauling purposes, but for safety. A RADIAL FELL TANK ENGINE. BUILT BY MESSRS. NEILSON AND CO., GLASGOW. wheels, having the flanges under the rails, which the wheels therefore cannot mount—an arrangement which, as events . . . Safety Wheels. have proved, makes it prac- tically impossible for locomotives or rolling stock to leave the track under conditions that, but for such a safeguard, would have dis- astrous results. Also it has been found in practice that where the centre rail is laid there is less friction, and consequently less wear and tear, on curves, as the horizontal wheels take the pressure due to centrifugal force and prevent the flanges of the carrying wheels grinding against the outer rail. For control purposes the ordinary brakes are supplemented on every vehicle by centre-rail brakes, worked by hand or by power. Two powerful steel jaws press cast- iron brake blocks against th© rail so tightly that, if proper care be exercised, a train cannot possibly get out of control. A locomotive incorporating the principles sketched above was built at Birkenhead, and tested on the High Peak Railway, Derbyshire, with results so encouraging as to justify ap- plication being made shortly afterwards to the French and Italian Governments for con- cessions to build the Mont Cenis Summit Railway. The two Governments sanctioned the con- struction of the line on the condition that a trial of the system should be mad© on the