Discoveries and Inventions of the Nineteenth Century

by Robert Routledge

Fig. 57.—Railway Embankment near Bath.

PLATE VI.
MOUNT WASHINGTON INCLINED TRACK.

INCLINED RAILWAYS.

The construction of railways over lofty ranges of mountains will be found illustrated by the brief notices in other pages of the Union Pacific line in the United States, and of the St. Gothard railway over the Alps. In such cases, the track has been to a great extent carried over the spurs or along the sides of the mountains, so that such inclines might be obtained as the ordinary locomotive was capable of ascending. The expensive operation of tunnelling was resorted to only where sinuous deviations from the more direct route involved a still greater expenditure of initial cost, or a continual waste of time and energy in the actual working of the line. Sometimes winding tracks, almost returning by snake-like loops on their own route, as projected on the map, were required in order that the ascent could be made with an incline practicable for the ordinary locomotive. In the earlier development of railways, there were to be met with cable inclines, where the traction of the locomotive had to be superseded or supplemented by that of a rope or chain wound round a drum actuated by a stationary steam-engine. The more powerful locomotives of the present day are able to mount grades of such inclination that the employment of cable traction is no longer requisite, except in but a few cases. Railways had carried passengers about in all parts of the world for many years before the engineer addressed himself to the problem of easily and quickly taking people up heights of steep and toilsome ascent, sought generally for the sake of the prospect, etc. Such, at least, has been the object of most of the inclined railways already constructed, but to this their utility is by no means limited, and as their safety and stability has been proved by many years of use, they may find wider applications than the gratification of the tourist and pleasure-seeker.

The toothed rail or rack which was formerly supposed necessary to obtain power of traction on rails has been already mentioned (p. [101]), and as early as 1812 such a contrivance appears to have been in use in England, near Leeds, the invention of a Mr. Blenkinsop. This mode of traction received no development or improvement worthy of notice until Mr. S. Marsh constructed, in 1866, a railway ladder—for so it may be called—for the ascent of Mount Washington in the United States. In this case there was a centre rail formed of iron, angle iron laid between and parallel to the metals on which ran the wheels of the carriages. In this centre rail angle irons were connected by round bars of wrought iron, which the teeth of a pinion of the locomotive engaged, so that a climbing action, resembling somewhat that of a wheel entering on the successive rounds of a ladder, was produced, and in this way an ascensive power was obtained sufficient to overcome gravity, the gradient not much exceeding a rise of one foot in three at any point (12 vertical to 32 horizontal). This railway was completed in 1869, and for more than a quarter of a century it has carried thousands of tourists to the summit of Mount Washington without a single fatal accident. This system of ascending mountains was soon adopted in Europe with certain improvements, for in 1870 an inclined railway was constructed to the summit of the Rigi, in which a system of involute gearing was substituted for the ladder-like rounds of Mr. Marsh. A certain vibratory action, due to the successive engagements of the teeth in the central rack, which was somewhat disagreeable for passengers, was soon afterwards obviated in the Abt system, in which two racks are used, with the teeth of one opposite the spaces of the other, and a double pinion provided, so that greater uniformity in the acting power is obtained. With certain modifications in detail, such as horizontal instead of vertical pinions, this system has been largely adopted wherever cables have been dispensed with. In the inclined railway by which Mount Pilatus, near Lucerne, is now ascended, horizontal teeth project from both sides of a centre rail, and these are engaged by horizontal pinions. The incline here is very steep, being in places nearly 30 degrees; teeth perpendicular to the plane of the incline would have offered a less margin of safety than those on the plan actually adopted. In some places, as among the Alps, and more particularly in South America, there are railways in which the ordinary mode of traction and that with the rack are combined; that is, where the gradient exceeds the ordinary limit, a central rack-rail is laid down, on approaching which the engineer slackens his speed, and allows pinions, moved by the locomotive, to become engaged in the double rack, by which he slowly climbs the steep ascent until a level tract is reached which permits of the ordinary traction being resumed.

Fig. 57a.—Train Ascending the Rigi.

Instead of climbing the inclines by rack-work rails, there is another system which offers great advantages for economy in working, and one generally resorted to where the incline can be made in one vertical plane. This is the balanced cable, in which the gravitation force of a descending car or train is utilised to draw up, or assist to draw up, the ascending car or train. These cars are attached to the ends of a cable which passes round a drum at the top of the incline, and means are provided, according to circumstances, so that the drum may be turned, or its revolutions controlled by brakes. When there is a water supply at the upper end of the incline, a simple and economical mode of working the cable is available; for all that is necessary is to provide each car with a water-tank capable of being rapidly filled and emptied. The upper car is made the heavier when required, by filling its tank with water, when it raises the lower car, and on itself arriving at the bottom, the water is discharged before the load to be taken up is received.