Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/262

Rh RAILWAY which pass through their flanges and the sleeper together. At the joints they are fortified by square iron plates laid under the joints, through which fang-bolts are passed. The longitudinals are con- nected and kept to gauge by transoms or cross-ties at intervals. The minimum weight of ordinary flange rails is about 45 Ib per lineal yard. If the weight is less than this for main lines the upper bearing surface is objectionably narrow, and it is scarcely high enough above the sleepers. The maximum weight of flange rafts is about 80 ft per lineal yard. Flange rails, like headed rails, are laid on transverse sleepers, to which they are fixed, most com- monly by means of screws, spikes, or flange bolts and nuts. In all cases 'it is preferable to effect the fastening of steel rails without piercing them in the flange, as they are materially weakened by such perforations. In the United States (also very largely in Germany, Canada, and Mexico) the Vignoles rail is universally used for railways, varying in weight from 67 or 70 Ib per yard on a few leading lines to 30 tt> on narrow-gauge railways. No railroads with any considerable traffic are now laid down with rails of less weight than 60 Ib per yard. The Pennsylvania Railroad, laid to a gauge of 4 feet 9 inches, is constructed of flange rails of two sections, one of 60 Ib per yard 4^ inches high, the other of 67 Ib 4J inches high, in lengths of 30 feet The fishes or splices are 2 feet in length, held by four bolts and nuts. The outer splice is formed with a horizontal flange or "tongue," which overhangs the flange of the rail and is spiked to the sleeper. Allowance for expansion when the rails are laid in winter is provided by laying the rails five-sixteenths of an inch apart, endwise ; in summer a space of only-one-sixteenth of an inch in width is allowed. The cross sleepers are 8 inches wide by 7 deep, and are 8 feet in length ; they are laid so closely that the maximum distance apart between centres does not exceed 2 feet. There are sixteen sleepers for each length of 30 feet, and the sleepers at the joints are laid with a clearance of over 10 inches between them. The rails are fastened by spikes to the sleepers at the inside and the outside. The width for the double line of way at the formation level is 31 feet 4 inches in cuttings ; and on embankments the width of the formation is 24 feet 3 inches, sloping from the centre at the rate of 1 in 20. The ballast is laid to a depth of not less than 12 inches under the sleepers, and is filled in to the level of the upper surface of the sleepers. Where stone ballast is used it is broken uniformly to a gauge of 2 inches in diameter. For double lines of way large stones are placed in the bottom, at the centre, between the lines to provide for drainage ; but the stones are not placed under the ends of the sleepers ; thus water is drained off rapidly. Metallic Permanent Way. Metallic permanent way, in which the sleepers are of iron, has been much employed in tropical nent way. countries, and is now to some ex- tent adopted in France and in Ger- many. The oldest and most widely "~ used system of me- n tallic way is that of ^ Mr H, Greaves, who ? ; in 1846 introduced ^ a spherical or bowl sleeper of cast-iron, having the chair for the rail cast on its summit (see fig. 38). Every second pair of sleepers are connected and held Fio- 38. Greaves's cast-iron sleepers, to gauge by transverse tie-bars, which pass through and are bolted to them. The form of the sleeper is strong, it holds well in the ground, the chair is not liable to be detached, the whole bearing surface is directly beneath the road, the ballast is kept dry and elastic, and there is a simple means of packing the sleeper through holes in the top, with a pointed rammer from the surface, so that the sleeper and the rail can be forced upwards without dis- turbing the general bed of ballast. They may also be lowered by taking out a portion of ballast from the interior. Another system, Mr W. Bridges Adams's " suspended girder rail," is shown in fig. 39. The rail __ ^ ^ is 7 inches deep, ^tyr^* ~^ = T^^ == " weighing 65 Ib per 1* "tJ lineal yard, and is Fio. 39. Suspended girder raiL suspended by continuous angle-wires, or side wings bolted to it, ana bedded in the ballast ; and, as the bearing surface on the ballast was approximated to the bearing surface of the rail, a great degree or stability was anticipated. Wrought -iron trans- verse sleepers were first tried in Belgium in 1862, then in France and in Portugal, and afterwards in Germany. There are various systems, most of which were' unsatisfactory, but the Vautherin sleeper, first tried in 1864 on the Lyons railway, has Metallic perma- been successful. It is hollow in section, of the form A truncated, supposing the upper part of the letter to be removed, presenting a flat bearing surface, 3| inches wide, for a flange rail. It is 8 feet in length and 9 inches wide over the flanges forming the base. It is three-eighths of an inch thick at the centre and is only half that thickness in the wings. The rail is fixed to the sleeper with gibs and cotters. It has been reported that the motion over the Vautherin sleepers is much easier than that over sleepers of oak, and that in consequence the cost of maintenance is comparatively low. It is stated that amongst a number of rails laid for trial under similar conditions, some of them on wooden sleepers and some of them on Vautherin sleepers, the number of defective rails amounted to only 2 per cent, of those laid on Vautherin sleepers against 13 per cent, of those laid on wood. It was found that if the Vautherin sleepers were not at least 8 feet in length they failed at the ends, and that even for this length it was expedient to strengthen them at the angles. It was also found that large and hard ballast, or broken stoijea or broken slag, aggravated the tend- ency to give way. Ballast of ashes produced a similar bad effect, and also caused the sleepers to rust. On the contrary, ballast of gravel, of a marly character, adapted itself admirably to the form of the sleeper. The system of fastening the rails to the sleepers by gibs and cotters has been abandoned in favour of clips and hook- bolts. The Hartwich system of iron way need not be described here, having always given bad results. The Hilf system of iron way consists of two parts, an iron longitudinal sleeper and a flange rail of steel. It is simple, easily laid and maintained, and econo- mical. The sleeper is in section like the letter E, bevelled at the angles, having an upper flat surface and three flanges downwards. It is 12 inches wide and about 2 deep ; and it can be rolled to lengths of 30 feet and only one-third of an inch in thickness, and to a weight of 59 Ib per yard. The rail is 4 '32 inches high, with 2 '32 inches width of table, 3 '40 width of flange base, and four- tenths of an inch thickness of web. It is rolled in lengths of 30 feet and weighs 51^ R> per yard. It is fish-jointed and is fixed to the sleeper with two rows of bolts and nuts at intervals of from 30 to 40 inches. The gauge is preserved by means of 1-inch tie-rods, screwed at both ends with nuts. One tie-rod is sufficient for each length of rail. The combined rail and sleeper, placed on supports 54 inches apart, can carry 18 tons at their middle, without im- pairing their elastic strength. LOCOMOTIVE POWER. Locomotives may broadly be reduced to two classes, according to the situation of the working cylinders. In the first class these are within the framing, under the boiler, with the main driving axle cranked at two points to receive the power from the two cylinders ; in the second class they are outside the framing, and connected, not to the axle, which is straight, but to crank-pins fixed between the spokes of the wheels, in connexion with the nave. From these distinguishing features the two types of engines are known respectively as " inside cylinder locomotives " and "out- side cylinder locomotives." In the latter the general contour of the cylinders is usually visible at the fore -end of the machine. The tenders have six or four wheels, according to the taste of the designer, and they are supplied with powerful brakes, worked by screws, with blocks of wood placed against each wheel. A water- tank forms the upper part of the tender, namely, the two sides and the back, usually in the form of a horse-shoe, holding from 1000 to 3000 gallons ; and in the hollow of the shoe the fuel is deposited, of which a full charge may weigh from 30 cwt. to 3 J tons. The engine and the tender are sustained on springs placed over the axle-bearings. Again, there is the general classification of locomotives into passenger engines and goods and mineral engines. As the power of the engine is brought into action through the grip of the driving wheels upon the rails, it is necessary, for the exertion of maximum power in goods engines, to make two or more pairs of the wheels of one -size, and transmit the driving force from the central pair of wheels to the front and back pairs by means of coupling-rods attached to crank-pins at the naves of the wheels. Such engines are called "six-coupled," and for them the most convenient combination is with inside cylinders. When the cylinders are outside it is usual to couple only the hind pair of wheels to the driving wheels, making a " four-coupled " engine, the leading or front wheels being of smaller diameter than the driving-wheels, and so leaving room for the convenient placement of the cylinders. The six-coupled engine can take the heaviest train on a good straight railway, that is, one free for the most part from curves ; but four-coupled engines work more economic- ally on lines with frequent curves, and may be made so as to take, in average practice, as great a load as six-coupled engines. Pass- enger locomotives have usually been constructed with a single pair of driving-wheels, for free running at high speeds; but as traffic became heavier four-coupled-wheel passenger engines came into vogue ; and express trains are now for the most part worked with four-coupled engines. In recent years the forepart of engines has in many cases been placed on a four-wheeled truck connected Types engine