MOUNTAIN RAILWAYS. The term mountain railway is applied to lines whose grades are too steep to be operated by locomotives, depending upon adhesion only for their drawing power, and which, therefore, necessitate the use of some special system of securing greater traction power. Several such systems are employed. The two principal ones are the Fell system, with a cen tral, elevated, double-headed rail laid sideways, which is gripped by horizontal wheels on each side, which greatly augment the adhesion, and the system with central racks in which vertical cog-wheels work, whereby the adhesion of the ordinary driving wheels is greatly assisted in drawing a train up the incline, and the descent of the train is kept under control. This latter system embraces the Riggenbach, Abt, and other systems. In tourist lines ascending the steep sides of mountains for the sake of the views, a eog-wheel working in a central track is generally used as the sole means of propulsion up the inclines. Lastly, where the ascent is steep, straight, and fairly short, a cable is employed for hauling up the vehicles, resembling in prin ciple the inclines worked by ropes in mines, a system which has also occasionally been adopted for the steep inclines on ordinary railways.
The central-rail system was first adopted for crossing the Mont Cenis Pass by a railway laid mainly along the road between Saint-Michel and Susa, a distance of 4S miles, having a gauge of 3 feet inches and surmounting a difference of level of 5300 feet between Susa and the sum with a total variation in level between its termini of about 9000 feet. The ruling gradient was 1 in 12. the average gradient about 1 in 17, and the central rail, raised inches above the ordinary rail-level, was laid along all gradients exceeding 1 in 25: while the minimum radius for the curves was 2 chains. The greatest train load carried over the Mont Cenis Fell Railway was 36 tons, and the heaviest locomotives em ployed on it weighed 26 tons. In this system the grip of the horizontal wheel on the central rail not merely secures sufficient adhesion to mount steep inclines, but also servee, as a very effective brake in the descent, and keeps the locomotive firmly on the line in going around sharp curves.
The Riamtaka incline. on the Wellington and Featherstone Railway in New Zealand, with a gradient of 1 in 15 for 2!:, miles, and a total of S69 feet, opened about 1879, having a gauge, like the rest of the railway, of 3 feet 6 inches, and curves of 5 chains radius, was laid with a central rail, and the traffic on the incline. has been worked continuously by a loco
motive with horizontal wheels gripping the cen tral rail. Each engine, weighing about 36 tons, n draw a maximum train load of 70 tons up the incline: and in order to avoid an undue strain on the draw-bars, the three engines em ployed for taking up a heavy train are so dis tributed between the carriages as to enable each to draw itA own load. The system has proved safe and satisfactory, and well adapted for run ning around sharp curves; while the saving in cost of construction by adopting the incline on this particular railway, instead of a more cir cuitous course, to obtain flatter gradients. readily surmounted by ordinary locomotives, was esti mated at £100,000.
A solid central rack was introduced for the first time in 1847 on an incline of the Madison and Indianapolis Railway near Aladison, Ind.
It was 1 miles long, with gradients of I in to 1 in 17. The rack railway, however, which was the precursor of the numerous Swiss mountain railways for tourists, was the line, three miles in length, constructed up to the top of Mount Washington in New Hampshire in 1886 69. rising altogether to a height of 3600 feet, with ruling gradient of 1 in 3. The rack in this case was formed in lengths of 10 feet, with two parallel angle-irons, 4 inches apart, connected by a series of round wrought-iron bars constitut ing the teeth of the rack, which resembles a ladder laid on the ground. The locomotives, provided with a central cog-wheel working in the ladder-raek, push the vehicles up the moun tain at a rate of about three miles an hour. The first rack railway carried out in Europe up a mountain slope was the Vitznau-Rigi Rail way, constructed from Vitznau, on the Lake of Lucerne, to the summit of the Rigi in LS69-73, rising 4472 feet in its course of miles, with a ruling gradient of 1 in 4 for about a third of its length. and never less than I in 6. except at the stations. The locomotive on these mountain lines is always placed below the carriages, so as to push them up the inclines and control their descent. the speed of the trains on the Rigi line being limited to between three and four miles an hour.